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-rw-r--r--users/Profpatsch/netencode/Netencode.hs433
-rw-r--r--users/Profpatsch/netencode/Netencode/Parse.hs102
-rw-r--r--users/Profpatsch/netencode/README.md28
-rw-r--r--users/Profpatsch/netencode/default.nix149
-rw-r--r--users/Profpatsch/netencode/gen.nix40
-rw-r--r--users/Profpatsch/netencode/netencode-mustache.rs29
-rw-r--r--users/Profpatsch/netencode/netencode.cabal74
-rw-r--r--users/Profpatsch/netencode/netencode.rs627
-rw-r--r--users/Profpatsch/netencode/pretty.rs73
9 files changed, 1191 insertions, 364 deletions
diff --git a/users/Profpatsch/netencode/Netencode.hs b/users/Profpatsch/netencode/Netencode.hs
new file mode 100644
index 0000000000..ca93ab2fef
--- /dev/null
+++ b/users/Profpatsch/netencode/Netencode.hs
@@ -0,0 +1,433 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+
+module Netencode where
+
+import Control.Applicative (many)
+import Data.Attoparsec.ByteString qualified as Atto
+import Data.Attoparsec.ByteString.Char8 qualified as Atto.Char
+import Data.ByteString qualified as ByteString
+import Data.ByteString.Builder (Builder)
+import Data.ByteString.Builder qualified as Builder
+import Data.ByteString.Lazy qualified as ByteString.Lazy
+import Data.Fix (Fix (Fix))
+import Data.Fix qualified as Fix
+import Data.Functor.Classes (Eq1 (liftEq))
+import Data.Int (Int16, Int32, Int64, Int8)
+import Data.Map.NonEmpty (NEMap)
+import Data.Map.NonEmpty qualified as NEMap
+import Data.Semigroup qualified as Semi
+import Data.String (IsString)
+import Data.Word (Word16, Word32, Word64)
+import GHC.Exts (fromString)
+import Hedgehog qualified as Hedge
+import Hedgehog.Gen qualified as Gen
+import Hedgehog.Range qualified as Range
+import PossehlAnalyticsPrelude
+import Text.Show.Deriving
+import Prelude hiding (sum)
+
+-- | Netencode type base functor.
+--
+-- Recursive elements have a @rec@.
+data TF rec
+  = -- | Unit value
+    Unit
+  | -- | Boolean (2^1)
+    N1 Bool
+  | -- | Byte (2^3)
+    N3 Word8
+  | -- | 64-bit Natural (2^6)
+    N6 Word64
+  | -- | 64-bit Integer (2^6)
+    I6 Int64
+  | -- | Unicode Text
+    Text Text
+  | -- | Arbitrary Bytestring
+    Bytes ByteString
+  | -- | A constructor of a(n open) Sum
+    Sum (Tag Text rec)
+  | -- | Record
+    Record (NEMap Text rec)
+  | -- | List
+    List [rec]
+  deriving stock (Show, Eq, Functor)
+
+instance Eq1 TF where
+  liftEq _ Unit Unit = True
+  liftEq _ (N1 b) (N1 b') = b == b'
+  liftEq _ (N3 w8) (N3 w8') = w8 == w8'
+  liftEq _ (N6 w64) (N6 w64') = w64 == w64'
+  liftEq _ (I6 i64) (I6 i64') = i64 == i64'
+  liftEq _ (Text t) (Text t') = t == t'
+  liftEq _ (Bytes b) (Bytes b') = b == b'
+  liftEq eq (Sum t) (Sum t') = eq (t.tagVal) (t'.tagVal)
+  liftEq eq (Record m) (Record m') = liftEq eq m m'
+  liftEq eq (List xs) (List xs') = liftEq eq xs xs'
+  liftEq _ _ _ = False
+
+-- | A tagged value
+data Tag tag val = Tag
+  { tagTag :: tag,
+    tagVal :: val
+  }
+  deriving stock (Show, Eq, Functor)
+
+$(Text.Show.Deriving.deriveShow1 ''Tag)
+$(Text.Show.Deriving.deriveShow1 ''TF)
+
+-- | The Netencode type
+newtype T = T {unT :: Fix TF}
+  deriving stock (Eq, Show)
+
+-- | Create a unit
+unit :: T
+unit = T $ Fix Unit
+
+-- | Create a boolean
+n1 :: Bool -> T
+n1 = T . Fix . N1
+
+-- | Create a byte
+n3 :: Word8 -> T
+n3 = T . Fix . N3
+
+-- | Create a 64-bit natural
+n6 :: Word64 -> T
+n6 = T . Fix . N6
+
+-- | Create a 64-bit integer
+i6 :: Int64 -> T
+i6 = T . Fix . I6
+
+-- | Create a UTF-8 unicode text
+text :: Text -> T
+text = T . Fix . Text
+
+-- | Create an arbitrary bytestring
+bytes :: ByteString -> T
+bytes = T . Fix . Bytes
+
+-- | Create a tagged value from a tag name and a value
+tag :: Text -> T -> T
+tag key val = T $ Fix $ Sum $ coerce @(Tag Text T) @(Tag Text (Fix TF)) $ Tag key val
+
+-- | Create a record from a non-empty map
+record :: NEMap Text T -> T
+record = T . Fix . Record . coerce @(NEMap Text T) @(NEMap Text (Fix TF))
+
+-- | Create a list
+list :: [T] -> T
+list = T . Fix . List . coerce @[T] @([Fix TF])
+
+-- | Stable encoding of a netencode value. Record keys will be sorted lexicographically ascending.
+netencodeEncodeStable :: T -> Builder
+netencodeEncodeStable (T fix) = Fix.foldFix (netencodeEncodeStableF id) fix
+
+-- | Stable encoding of a netencode functor value. Record keys will be sorted lexicographically ascending.
+--
+-- The given function is used for encoding the recursive values.
+netencodeEncodeStableF :: (rec -> Builder) -> TF rec -> Builder
+netencodeEncodeStableF inner tf = builder go
+  where
+    -- TODO: directly pass in BL?
+    innerBL = fromBuilder . inner
+    go = case tf of
+      Unit -> "u,"
+      N1 False -> "n1:0,"
+      N1 True -> "n1:1,"
+      N3 w8 -> "n3:" <> fromBuilder (Builder.word8Dec w8) <> ","
+      N6 w64 -> "n6:" <> fromBuilder (Builder.word64Dec w64) <> ","
+      I6 i64 -> "i6:" <> fromBuilder (Builder.int64Dec i64) <> ","
+      Text t ->
+        let b = fromText t
+         in "t" <> builderLenDec b <> ":" <> b <> ","
+      Bytes b -> "b" <> builderLenDec (fromByteString b) <> ":" <> fromByteString b <> ","
+      Sum (Tag key val) -> encTag key val
+      Record m ->
+        -- NEMap uses Map internally, and that folds in lexicographic ascending order over the key.
+        -- Since these are `Text` in our case, this is stable.
+        let mBuilder = m & NEMap.foldMapWithKey encTag
+         in "{" <> builderLenDec mBuilder <> ":" <> mBuilder <> "}"
+      List xs ->
+        let xsBuilder = xs <&> innerBL & mconcat
+         in "[" <> builderLenDec xsBuilder <> ":" <> xsBuilder <> "]"
+      where
+        encTag key val =
+          let bKey = fromText key
+           in "<" <> builderLenDec bKey <> ":" <> bKey <> "|" <> innerBL val
+
+-- | A builder that knows its own size in bytes
+newtype BL = BL (Builder, Semi.Sum Natural)
+  deriving newtype (Monoid, Semigroup)
+
+instance IsString BL where
+  fromString s =
+    BL
+      ( fromString @Builder s,
+        fromString @ByteString s
+          & ByteString.length
+          & intToNatural
+          & fromMaybe 0
+          & Semi.Sum
+      )
+
+-- | Retrieve the builder
+builder :: BL -> Builder
+builder (BL (b, _)) = b
+
+-- | Retrieve the bytestring length
+builderLen :: BL -> Natural
+builderLen (BL (_, len)) = Semi.getSum $ len
+
+-- | Take a 'BL' and create a new 'BL' that represents the length as a decimal integer
+builderLenDec :: BL -> BL
+builderLenDec (BL (_, len)) =
+  let b = Builder.intDec $ (len & Semi.getSum & fromIntegral @Natural @Int)
+   in b & fromBuilder
+
+-- | Create a 'BL' from a 'Builder'.
+--
+-- Not efficient, goes back to a lazy bytestring to get the length
+fromBuilder :: Builder -> BL
+fromBuilder b =
+  BL
+    ( b,
+      b
+        & Builder.toLazyByteString
+        & ByteString.Lazy.length
+        & fromIntegral @Int64 @Natural
+        & Semi.Sum
+    )
+
+-- | Create a 'BL' from a 'ByteString'.
+fromByteString :: ByteString -> BL
+fromByteString b =
+  BL
+    ( Builder.byteString b,
+      b
+        & ByteString.length
+        & fromIntegral @Int @Natural
+        & Semi.Sum
+    )
+
+-- | Create a 'BL' from a 'Text'.
+fromText :: Text -> BL
+fromText t = t & textToBytesUtf8 & fromByteString
+
+-- | Parser for a netencode value.
+netencodeParser :: Atto.Parser T
+netencodeParser = T <$> go
+  where
+    go = Fix <$> netencodeParserF go
+
+-- | Parser for one level of a netencode value. Requires a parser for the recursion.
+netencodeParserF :: Atto.Parser rec -> Atto.Parser (TF rec)
+netencodeParserF inner = do
+  typeTag <- Atto.Char.anyChar
+  case typeTag of
+    't' -> Text <$> textParser
+    'b' -> Bytes <$> bytesParser
+    'u' -> unitParser
+    '<' -> Sum <$> tagParser
+    '{' -> Record <$> recordParser
+    '[' -> List <$> listParser
+    'n' -> naturalParser
+    'i' -> I6 <$> intParser
+    c -> fail ([c] <> " is not a valid netencode tag")
+  where
+    bytesParser = do
+      len <- boundedDecimalFail Atto.<?> "bytes is missing a digit specifying the length"
+      _ <- Atto.Char.char ':' Atto.<?> "bytes did not have : after length"
+      bytes' <- Atto.take len
+      _ <- Atto.Char.char ',' Atto.<?> "bytes did not end with ,"
+      pure bytes'
+
+    textParser = do
+      len <- boundedDecimalFail Atto.<?> "text is missing a digit specifying the length"
+      _ <- Atto.Char.char ':' Atto.<?> "text did not have : after length"
+      text' <-
+        Atto.take len <&> bytesToTextUtf8 >>= \case
+          Left err -> fail [fmt|cannot decode text as utf8: {err & prettyError}|]
+          Right t -> pure t
+      _ <- Atto.Char.char ',' Atto.<?> "text did not end with ,"
+      pure text'
+
+    unitParser = do
+      _ <- Atto.Char.char ',' Atto.<?> "unit did not end with ,"
+      pure $ Unit
+
+    tagParser = do
+      len <- boundedDecimalFail Atto.<?> "tag is missing a digit specifying the length"
+      _ <- Atto.Char.char ':' Atto.<?> "tag did not have : after length"
+      tagTag <-
+        Atto.take len <&> bytesToTextUtf8 >>= \case
+          Left err -> fail [fmt|cannot decode tag key as utf8: {err & prettyError}|]
+          Right t -> pure t
+      _ <- Atto.Char.char '|' Atto.<?> "tag was missing the key/value separator (|)"
+      tagVal <- inner
+      pure $ Tag {..}
+
+    recordParser = do
+      -- TODO: the record does not use its inner length because we are descending into the inner parsers.
+      -- This is a smell! In theory it can be used to skip parsing the whole inner keys.
+      _len <- boundedDecimalFail Atto.<?> "record is missing a digit specifying the length"
+      _ <- Atto.Char.char ':' Atto.<?> "record did not have : after length"
+      record' <-
+        many (Atto.Char.char '<' >> tagParser) <&> nonEmpty >>= \case
+          Nothing -> fail "record is not allowed to have 0 elements"
+          Just tags ->
+            pure $
+              tags
+                <&> (\t -> (t.tagTag, t.tagVal))
+                -- later keys are preferred if they are duplicates, according to the standard
+                & NEMap.fromList
+      _ <- Atto.Char.char '}' Atto.<?> "record did not end with }"
+      pure record'
+
+    listParser = do
+      -- TODO: the list does not use its inner length because we are descending into the inner parsers.
+      -- This is a smell! In theory it can be used to skip parsing the whole inner keys.
+      _len <- boundedDecimalFail Atto.<?> "list is missing a digit specifying the length"
+      _ <- Atto.Char.char ':' Atto.<?> "list did not have : after length"
+      -- TODO: allow empty lists?
+      list' <- many inner
+      _ <- Atto.Char.char ']' Atto.<?> "list did not end with ]"
+      pure list'
+
+    intParser = do
+      let p :: forall parseSize. (Bounded parseSize, Integral parseSize) => (Integer -> Atto.Parser Int64)
+          p n = do
+            _ <- Atto.Char.char ':' Atto.<?> [fmt|i{n & show} did not have : after length|]
+            isNegative <- Atto.option False (Atto.Char.char '-' <&> \_c -> True)
+            int <-
+              boundedDecimal @parseSize >>= \case
+                Nothing -> fail [fmt|cannot parse into i{n & show}, the number is too big (would overflow)|]
+                Just i ->
+                  pure $
+                    if isNegative
+                      then -- TODO: this should alread be done in the decimal parser, @minBound@ cannot be parsed cause it’s one more than @(-maxBound)@!
+                        (-i)
+                      else i
+            _ <- Atto.Char.char ',' Atto.<?> [fmt|i{n & show} did not end with ,|]
+            pure $ fromIntegral @parseSize @Int64 int
+      digit <- Atto.Char.digit
+      case digit of
+        -- TODO: separate parser for i1 and i2 that makes sure the boundaries are right!
+        '1' -> p @Int8 1
+        '2' -> p @Int8 2
+        '3' -> p @Int8 3
+        '4' -> p @Int16 4
+        '5' -> p @Int32 5
+        '6' -> p @Int64 6
+        '7' -> fail [fmt|i parser only supports numbers up to size 6, was 7|]
+        '8' -> fail [fmt|i parser only supports numbers up to size 6, was 8|]
+        '9' -> fail [fmt|i parser only supports numbers up to size 6, was 9|]
+        o -> fail [fmt|i number with length {o & show} not possible|]
+
+    naturalParser = do
+      let p :: forall parseSize finalSize. (Bounded parseSize, Integral parseSize, Num finalSize) => (Integer -> Atto.Parser finalSize)
+          p n = do
+            _ <- Atto.Char.char ':' Atto.<?> [fmt|n{n & show} did not have : after length|]
+            int <-
+              boundedDecimal @parseSize >>= \case
+                Nothing -> fail [fmt|cannot parse into n{n & show}, the number is too big (would overflow)|]
+                Just i -> pure i
+
+            _ <- Atto.Char.char ',' Atto.<?> [fmt|n{n & show} did not end with ,|]
+            pure $ fromIntegral @parseSize @finalSize int
+      let b n = do
+            _ <- Atto.Char.char ':' Atto.<?> [fmt|n{n & show} did not have : after length|]
+            bool <-
+              (Atto.Char.char '0' >> pure False)
+                <|> (Atto.Char.char '1' >> pure True)
+            _ <- Atto.Char.char ',' Atto.<?> [fmt|n{n & show} did not end with ,|]
+            pure bool
+
+      digit <- Atto.Char.digit
+      case digit of
+        -- TODO: separate parser for n1 and n2 that makes sure the boundaries are right!
+        '1' -> N1 <$> b 1
+        '2' -> N3 <$> p @Word8 @Word8 2
+        '3' -> N3 <$> p @Word8 @Word8 3
+        '4' -> N6 <$> p @Word16 @Word64 4
+        '5' -> N6 <$> p @Word32 @Word64 5
+        '6' -> N6 <$> p @Word64 @Word64 6
+        '7' -> fail [fmt|n parser only supports numbers up to size 6, was 7|]
+        '8' -> fail [fmt|n parser only supports numbers up to size 6, was 8|]
+        '9' -> fail [fmt|n parser only supports numbers up to size 6, was 9|]
+        o -> fail [fmt|n number with length {o & show} not possible|]
+
+-- | Parser for a bounded decimal that does not overflow the decimal.
+--
+--  via https://www.extrema.is/blog/2021/10/20/parsing-bounded-integers
+boundedDecimal :: forall a. (Bounded a, Integral a) => Atto.Parser (Maybe a)
+boundedDecimal = do
+  i :: Integer <- decimal
+  pure $
+    if (i :: Integer) > fromIntegral (maxBound :: a)
+      then Nothing
+      else Just $ fromIntegral i
+  where
+    -- Copied from @Attoparsec.Text@ and adjusted to bytestring
+    decimal :: (Integral a2) => Atto.Parser a2
+    decimal = ByteString.foldl' step 0 <$> Atto.Char.takeWhile1 Atto.Char.isDigit
+      where
+        step a c = a * 10 + fromIntegral (c - 48)
+{-# SPECIALIZE boundedDecimal :: Atto.Parser (Maybe Int) #-}
+{-# SPECIALIZE boundedDecimal :: Atto.Parser (Maybe Int64) #-}
+{-# SPECIALIZE boundedDecimal :: Atto.Parser (Maybe Word8) #-}
+{-# SPECIALIZE boundedDecimal :: Atto.Parser (Maybe Word64) #-}
+
+-- | 'boundedDecimal', but fail the parser if the decimal overflows.
+boundedDecimalFail :: Atto.Parser Int
+boundedDecimalFail =
+  boundedDecimal >>= \case
+    Nothing -> fail "decimal out of range"
+    Just a -> pure a
+
+-- | Hedgehog generator for a netencode value.
+genNetencode :: Hedge.MonadGen m => m T
+genNetencode =
+  Gen.recursive
+    Gen.choice
+    [ -- these are bundled into one Gen, so that scalar elements get chosen less frequently, and the generator produces nicely nested examples
+      Gen.frequency
+        [ (1, pure unit),
+          (1, n1 <$> Gen.bool),
+          (1, n3 <$> Gen.element [0, 1, 5]),
+          (1, n6 <$> Gen.element [0, 1, 5]),
+          (1, i6 <$> Gen.element [-1, 1, 5]),
+          (2, text <$> Gen.text (Range.linear 1 10) Gen.lower),
+          (2, bytes <$> Gen.bytes (Range.linear 1 10))
+        ]
+    ]
+    [ do
+        key <- Gen.text (Range.linear 3 10) Gen.lower
+        val <- genNetencode
+        pure $ tag key val,
+      record
+        <$> ( let k = Gen.text (Range.linear 3 10) Gen.lower
+                  v = genNetencode
+               in NEMap.insertMap
+                    <$> k
+                    <*> v
+                    <*> ( (Gen.map (Range.linear 0 3)) $
+                            (,) <$> k <*> v
+                        )
+            )
+    ]
+
+-- | Hedgehog property: encoding a netencode value and parsing it again returns the same result.
+prop_netencodeRoundtrip :: Hedge.Property
+prop_netencodeRoundtrip = Hedge.property $ do
+  enc <- Hedge.forAll genNetencode
+  ( Atto.parseOnly
+      netencodeParser
+      ( netencodeEncodeStable enc
+          & Builder.toLazyByteString
+          & toStrictBytes
+      )
+    )
+    Hedge.=== (Right enc)
diff --git a/users/Profpatsch/netencode/Netencode/Parse.hs b/users/Profpatsch/netencode/Netencode/Parse.hs
new file mode 100644
index 0000000000..184fb5f912
--- /dev/null
+++ b/users/Profpatsch/netencode/Netencode/Parse.hs
@@ -0,0 +1,102 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Netencode.Parse where
+
+import Control.Category qualified
+import Control.Selective (Selective)
+import Data.Error.Tree
+import Data.Fix (Fix (..))
+import Data.Functor.Compose
+import Data.List qualified as List
+import Data.Map.NonEmpty (NEMap)
+import Data.Map.NonEmpty qualified as NEMap
+import Data.Semigroupoid qualified as Semigroupiod
+import Data.Semigroupoid qualified as Semigroupoid
+import Data.Text qualified as Text
+import Netencode qualified
+import PossehlAnalyticsPrelude
+import Prelude hiding (log)
+
+newtype Parse from to
+  = -- TODO: the way @Context = [Text]@ has to be forwarded to everything is kinda shitty.
+    -- This is essentially just a difference list, and can probably be treated as a function in the output?
+    Parse (([Text], from) -> Validation (NonEmpty ErrorTree) ([Text], to))
+  deriving
+    (Functor, Applicative, Selective)
+    via ( Compose
+            ( Compose
+                ((->) ([Text], from))
+                (Validation (NonEmpty ErrorTree))
+            )
+            ((,) [Text])
+        )
+
+instance Semigroupoid Parse where
+  o p2 p1 = Parse $ \from -> case runParse' p1 from of
+    Failure err -> Failure err
+    Success to1 -> runParse' p2 to1
+
+instance Category Parse where
+  (.) = Semigroupoid.o
+  id = Parse $ \t -> Success t
+
+runParse :: Error -> Parse from to -> from -> Either ErrorTree to
+runParse errMsg parser t =
+  (["$"], t)
+    & runParse' parser
+    <&> snd
+    & first (nestedMultiError errMsg)
+    & validationToEither
+
+runParse' :: Parse from to -> ([Text], from) -> Validation (NonEmpty ErrorTree) ([Text], to)
+runParse' (Parse f) from = f from
+
+parseEither :: (([Text], from) -> Either ErrorTree ([Text], to)) -> Parse from to
+parseEither f = Parse $ \from -> f from & eitherToListValidation
+
+tAs :: (Netencode.TF (Fix Netencode.TF) -> Either ([Text] -> ErrorTree) to) -> Parse Netencode.T to
+tAs f = parseEither ((\(context, Netencode.T (Fix tf)) -> f tf & bimap ($ context) (context,)))
+
+key :: Text -> Parse (NEMap Text to) to
+key name = parseEither $ \(context, rec) ->
+  rec
+    & NEMap.lookup name
+    & annotate (errorTreeContext (showContext context) [fmt|Key "{name}" does not exist|])
+    <&> (addContext name context,)
+
+showContext :: [Text] -> Text
+showContext context = context & List.reverse & Text.intercalate "."
+
+addContext :: a -> [a] -> [a]
+addContext = (:)
+
+asText :: Parse Netencode.T Text
+asText = tAs $ \case
+  Netencode.Text t -> pure t
+  other -> typeError "of text" other
+
+asBytes :: Parse Netencode.T ByteString
+asBytes = tAs $ \case
+  Netencode.Bytes b -> pure b
+  other -> typeError "of bytes" other
+
+asRecord :: Parse Netencode.T (NEMap Text (Netencode.T))
+asRecord = tAs $ \case
+  Netencode.Record rec -> pure (rec <&> Netencode.T)
+  other -> typeError "a record" other
+
+typeError :: Text -> Netencode.TF ignored -> (Either ([Text] -> ErrorTree) b)
+typeError should is = do
+  let otherS = is <&> (\_ -> ("…" :: String)) & show
+  Left $ \context -> errorTreeContext (showContext context) [fmt|Value is not {should}, but a {otherS}|]
+
+orThrowParseError ::
+  Parse (Either Error to) to
+orThrowParseError = Parse $ \case
+  (context, Left err) ->
+    err
+      & singleError
+      & errorTreeContext (showContext context)
+      & singleton
+      & Failure
+  (context, Right to) -> Success (context, to)
diff --git a/users/Profpatsch/netencode/README.md b/users/Profpatsch/netencode/README.md
index 3058e36eaf..3538a110a6 100644
--- a/users/Profpatsch/netencode/README.md
+++ b/users/Profpatsch/netencode/README.md
@@ -1,6 +1,6 @@
 # netencode 0.1-unreleased
 
-[bencode][] and [netstring][]-inspired pipe format that should be trivial go generate correctly in every context (only requires a `byte_length()` and a `printf()`), easy to parse (100 lines of code or less), mostly human-decipherable for easy debugging, and support nested record and sum types.
+[bencode][] and [netstring][]-inspired pipe format that should be trivial to generate correctly in every context (only requires a `byte_length()` and a `printf()`), easy to parse (100 lines of code or less), mostly human-decipherable for easy debugging, and support nested record and sum types.
 
 
 ## scalars
@@ -73,7 +73,11 @@ A tag (`<`) gives a value a name. The tag is UTF-8 encoded, starting with its le
 ### records (products/records), also maps
 
 A record (`{`) is a concatenation of tags (`<`). It needs to be closed with `}`.
-If tag names repeat the later ones should be ignored. Ordering does not matter.
+
+If tag names repeat the *earlier* ones should be ignored.
+Using the last tag corresponds with the way most languages handle converting a list of tuples to Maps, by using a for-loop and Map.insert without checking the contents first. Otherwise you’d have to revert the list first or remember which keys you already inserted.
+
+Ordering of tags in a record does not matter.
 
 Similar to text, records start with the length of their *whole encoded content*, in bytes. This makes it possible to treat their contents as opaque bytestrings.
 
@@ -81,7 +85,7 @@ Similar to text, records start with the length of their *whole encoded content*,
 * A record with one empty field, `foo`: `{9:<3:foo|u,}`
 * A record with two fields, `foo` and `x`: `{21:<3:foo|u,<1:x|t3:baz,}`
 * The same record: `{21:<1:x|t3:baz,<3:foo|u,}`
-* The same record (later occurences of fields are ignored): `{28:<1:x|t3:baz,<3:foo|u,<1:x|u,}`
+* The same record (earlier occurences of fields are ignored): `{<1:x|u,28:<1:x|t3:baz,<3:foo|u,}`
 
 ### sums (tagged unions)
 
@@ -98,6 +102,24 @@ Similar to records, lists start with the length of their whole encoded content.
 * The list with text `foo` followed by i3 `-42`: `[14:t3:foo,i3:-42,]`
 * The list with `Some` and `None` tags: `[33:<4:Some|t3:foo,<4None|u,<4None|u,]`
 
+## parser security considerations
+
+The length field is a decimal number that is not length-restricted,
+meaning an attacker could give an infinitely long length (or extremely long)
+thus overflowing your parser if you are not careful.
+
+You should thus put a practical length limit to the length of length fields,
+which implicitely enforces a length limit on how long the value itself can be.
+
+Start by defining a max value length in bytes.
+Then count the number of decimals in that number.
+
+So if your max length is 1024 bytes, your length field can be a maximum `count_digits(1024) == 4` bytes long.
+
+Thus, if you restrict your parser to a length field of 4 bytes,
+it should also never parse anything longer than 1024 bytes for the value
+(plus 1 byte for the type tag, 4 bytes for the length, and 2 bytes for the separator & ending character).
+
 ## motivation
 
 TODO
diff --git a/users/Profpatsch/netencode/default.nix b/users/Profpatsch/netencode/default.nix
index db892cc9de..6e7dce489a 100644
--- a/users/Profpatsch/netencode/default.nix
+++ b/users/Profpatsch/netencode/default.nix
@@ -1,101 +1,133 @@
 { depot, pkgs, lib, ... }:
 
 let
-  netencode-rs = depot.nix.writers.rustSimpleLib {
+  netencode-rs = depot.nix.writers.rustSimpleLib
+    {
       name = "netencode";
       dependencies = [
         depot.third_party.rust-crates.nom
         depot.users.Profpatsch.execline.exec-helpers
       ];
-    } (builtins.readFile ./netencode.rs);
+    }
+    (builtins.readFile ./netencode.rs);
 
-  gen = import ./gen.nix { inherit lib; };
+  netencode-hs = pkgs.haskellPackages.mkDerivation {
+    pname = "netencode";
+    version = "0.1.0";
 
-  pretty-rs = depot.nix.writers.rustSimpleLib {
-    name = "netencode-pretty";
-    dependencies = [
-      netencode-rs
+    src = depot.users.Profpatsch.exactSource ./. [
+      ./netencode.cabal
+      ./Netencode.hs
+      ./Netencode/Parse.hs
     ];
-  } (builtins.readFile ./pretty.rs);
-
-  pretty = depot.nix.writers.rustSimple {
-    name = "netencode-pretty";
-    dependencies = [
-      netencode-rs
-      pretty-rs
-      depot.users.Profpatsch.execline.exec-helpers
+
+    libraryHaskellDepends = [
+      pkgs.haskellPackages.hedgehog
+      pkgs.haskellPackages.nonempty-containers
+      pkgs.haskellPackages.deriving-compat
+      pkgs.haskellPackages.data-fix
+      pkgs.haskellPackages.bytestring
+      pkgs.haskellPackages.attoparsec
+      pkgs.haskellPackages.pa-prelude
+      pkgs.haskellPackages.pa-label
+      pkgs.haskellPackages.pa-error-tree
     ];
-  } ''
+
+    isLibrary = true;
+    license = lib.licenses.mit;
+
+
+  };
+
+  gen = import ./gen.nix { inherit lib; };
+
+  pretty-rs = depot.nix.writers.rustSimpleLib
+    {
+      name = "netencode-pretty";
+      dependencies = [
+        netencode-rs
+      ];
+    }
+    (builtins.readFile ./pretty.rs);
+
+  pretty = depot.nix.writers.rustSimple
+    {
+      name = "netencode-pretty";
+      dependencies = [
+        netencode-rs
+        pretty-rs
+        depot.users.Profpatsch.execline.exec-helpers
+      ];
+    } ''
     extern crate netencode;
     extern crate netencode_pretty;
     extern crate exec_helpers;
 
     fn main() {
       let (_, prog) = exec_helpers::args_for_exec("netencode-pretty", 0);
-      let mut buf = vec![];
-      let u = netencode::u_from_stdin_or_die_user_error("netencode-pretty", &mut buf);
-      match netencode_pretty::Pretty::from_u(u).print_multiline(&mut std::io::stdout()) {
+      let t = netencode::t_from_stdin_or_die_user_error("netencode-pretty");
+      match netencode_pretty::Pretty::from_u(t.to_u()).print_multiline(&mut std::io::stdout()) {
         Ok(()) => {},
         Err(err) => exec_helpers::die_temporary("netencode-pretty", format!("could not write to stdout: {}", err))
       }
     }
   '';
 
-  netencode-mustache = depot.nix.writers.rustSimple {
-    name = "netencode_mustache";
-    dependencies = [
-      depot.users.Profpatsch.arglib.netencode.rust
-      netencode-rs
-      depot.third_party.rust-crates.mustache
-    ];
-  } (builtins.readFile ./netencode-mustache.rs);
+  netencode-mustache = depot.nix.writers.rustSimple
+    {
+      name = "netencode_mustache";
+      dependencies = [
+        depot.users.Profpatsch.arglib.netencode.rust
+        netencode-rs
+        depot.third_party.rust-crates.mustache
+      ];
+    }
+    (builtins.readFile ./netencode-mustache.rs);
 
 
-  record-get = depot.nix.writers.rustSimple {
-    name = "record-get";
-    dependencies = [
-      netencode-rs
-      depot.users.Profpatsch.execline.exec-helpers
-      depot.users.Profpatsch.arglib.netencode.rust
-    ];
-  } ''
+  record-get = depot.nix.writers.rustSimple
+    {
+      name = "record-get";
+      dependencies = [
+        netencode-rs
+        depot.users.Profpatsch.execline.exec-helpers
+      ];
+    } ''
     extern crate netencode;
-    extern crate arglib_netencode;
     extern crate exec_helpers;
     use netencode::{encode, dec};
     use netencode::dec::{Decoder, DecodeError};
 
     fn main() {
-        let mut buf = vec![];
         let args = exec_helpers::args("record-get", 1);
         let field = match std::str::from_utf8(&args[0]) {
             Ok(f) => f,
             Err(_e) => exec_helpers::die_user_error("record-get", format!("The field name needs to be valid unicode"))
         };
-        let u = netencode::u_from_stdin_or_die_user_error("record-get", &mut buf);
-        match (dec::RecordDot {field, inner: dec::AnyU }).dec(u) {
+        let t = netencode::t_from_stdin_or_die_user_error("record-get");
+        match (dec::RecordDot {field, inner: dec::AnyU }).dec(t.to_u()) {
             Ok(u) => encode(&mut std::io::stdout(), &u).expect("encoding to stdout failed"),
             Err(DecodeError(err)) => exec_helpers::die_user_error("record-get", err)
         }
     }
   '';
 
-  record-splice-env = depot.nix.writers.rustSimple {
-    name = "record-splice-env";
-    dependencies = [
-      netencode-rs
-      depot.users.Profpatsch.execline.exec-helpers
-    ];
-  } ''
+  record-splice-env = depot.nix.writers.rustSimple
+    {
+      name = "record-splice-env";
+      dependencies = [
+        netencode-rs
+        depot.users.Profpatsch.execline.exec-helpers
+      ];
+    } ''
     extern crate netencode;
     extern crate exec_helpers;
     use netencode::dec::{Record, Try, ScalarAsBytes, Decoder, DecodeError};
 
     fn main() {
-        let mut buf = vec![];
-        let u = netencode::u_from_stdin_or_die_user_error("record-splice-env", &mut buf);
+        let t = netencode::t_from_stdin_or_die_user_error("record-splice-env");
         let (_, prog) = exec_helpers::args_for_exec("record-splice-env", 0);
-        match Record(Try(ScalarAsBytes)).dec(u) {
+        match Record(Try(ScalarAsBytes)).dec(t.to_u()) {
             Ok(map) => {
                 exec_helpers::exec_into_args(
                     "record-splice-env",
@@ -109,13 +141,14 @@ let
     }
   '';
 
-  env-splice-record = depot.nix.writers.rustSimple {
-    name = "env-splice-record";
-    dependencies = [
-      netencode-rs
-      depot.users.Profpatsch.execline.exec-helpers
-    ];
-  } ''
+  env-splice-record = depot.nix.writers.rustSimple
+    {
+      name = "env-splice-record";
+      dependencies = [
+        netencode-rs
+        depot.users.Profpatsch.execline.exec-helpers
+      ];
+    } ''
     extern crate netencode;
     extern crate exec_helpers;
     use netencode::{T};
@@ -135,9 +168,11 @@ let
     }
   '';
 
-in depot.nix.utils.drvTargets {
+in
+depot.nix.readTree.drvTargets {
   inherit
     netencode-rs
+    netencode-hs
     pretty-rs
     pretty
     netencode-mustache
diff --git a/users/Profpatsch/netencode/gen.nix b/users/Profpatsch/netencode/gen.nix
index 305ff7b08d..efc9629ca0 100644
--- a/users/Profpatsch/netencode/gen.nix
+++ b/users/Profpatsch/netencode/gen.nix
@@ -27,29 +27,33 @@ let
   concatStrings = builtins.concatStringsSep "";
 
   record = lokv: netstring "{" "}"
-    (concatStrings (map ({key, val}: tag key val) lokv));
+    (concatStrings (map ({ key, val }: tag key val) lokv));
 
   list = l: netstring "[" "]" (concatStrings l);
 
   dwim = val:
-    let match = {
-      "bool" = n1;
-      "int" = i6;
-      "string" = text;
-      "set" = attrs:
-        # it could be a derivation, then just return the path
-        if attrs.type or "" == "derivation" then text "${attrs}"
-        else
-          record (lib.mapAttrsToList
-          (k: v: {
-            key = k;
-            val = dwim v;
-          }) attrs);
-      "list" = l: list (map dwim l);
-    };
-    in match.${builtins.typeOf val} val;
+    let
+      match = {
+        "bool" = n1;
+        "int" = i6;
+        "string" = text;
+        "set" = attrs:
+          # it could be a derivation, then just return the path
+          if attrs.type or "" == "derivation" then text "${attrs}"
+          else
+            record (lib.mapAttrsToList
+              (k: v: {
+                key = k;
+                val = dwim v;
+              })
+              attrs);
+        "list" = l: list (map dwim l);
+      };
+    in
+    match.${builtins.typeOf val} val;
 
-in {
+in
+{
   inherit
     unit
     n1
diff --git a/users/Profpatsch/netencode/netencode-mustache.rs b/users/Profpatsch/netencode/netencode-mustache.rs
index ee7bafed22..73ed5be1de 100644
--- a/users/Profpatsch/netencode/netencode-mustache.rs
+++ b/users/Profpatsch/netencode/netencode-mustache.rs
@@ -1,12 +1,12 @@
-extern crate netencode;
-extern crate mustache;
 extern crate arglib_netencode;
+extern crate mustache;
+extern crate netencode;
 
-use mustache::{Data};
-use netencode::{T};
+use mustache::Data;
+use netencode::T;
 use std::collections::HashMap;
-use std::os::unix::ffi::{OsStrExt};
-use std::io::{Read};
+use std::io::Read;
+use std::os::unix::ffi::OsStrExt;
 
 fn netencode_to_mustache_data_dwim(t: T) -> Data {
     match t {
@@ -25,27 +25,26 @@ fn netencode_to_mustache_data_dwim(t: T) -> Data {
         T::Record(xs) => Data::Map(
             xs.into_iter()
                 .map(|(key, val)| (key, netencode_to_mustache_data_dwim(val)))
-                .collect::<HashMap<_,_>>()
+                .collect::<HashMap<_, _>>(),
         ),
         T::List(xs) => Data::Vec(
             xs.into_iter()
                 .map(|x| netencode_to_mustache_data_dwim(x))
-                .collect::<Vec<_>>()
+                .collect::<Vec<_>>(),
         ),
     }
 }
 
 pub fn from_stdin() -> () {
-    let data = netencode_to_mustache_data_dwim(
-        arglib_netencode::arglib_netencode("netencode-mustache", Some(std::ffi::OsStr::new("TEMPLATE_DATA")))
-    );
+    let data = netencode_to_mustache_data_dwim(arglib_netencode::arglib_netencode(
+        "netencode-mustache",
+        Some(std::ffi::OsStr::new("TEMPLATE_DATA")),
+    ));
     let mut stdin = String::new();
     std::io::stdin().read_to_string(&mut stdin).unwrap();
     mustache::compile_str(&stdin)
-        .and_then(|templ| templ.render_data(
-            &mut std::io::stdout(),
-            &data
-        )).unwrap()
+        .and_then(|templ| templ.render_data(&mut std::io::stdout(), &data))
+        .unwrap()
 }
 
 pub fn main() {
diff --git a/users/Profpatsch/netencode/netencode.cabal b/users/Profpatsch/netencode/netencode.cabal
new file mode 100644
index 0000000000..7bff4487bb
--- /dev/null
+++ b/users/Profpatsch/netencode/netencode.cabal
@@ -0,0 +1,74 @@
+cabal-version:      3.0
+name:               netencode
+version:            0.1.0.0
+author:             Profpatsch
+maintainer:         mail@profpatsch.de
+
+
+common common-options
+  ghc-options:
+      -Wall
+      -Wno-type-defaults
+      -Wunused-packages
+      -Wredundant-constraints
+      -fwarn-missing-deriving-strategies
+
+  -- See https://downloads.haskell.org/ghc/latest/docs/users_guide/exts.html
+  -- for a description of all these extensions
+  default-extensions:
+      -- Infer Applicative instead of Monad where possible
+    ApplicativeDo
+
+    -- Allow literal strings to be Text
+    OverloadedStrings
+
+    -- Syntactic sugar improvements
+    LambdaCase
+    MultiWayIf
+
+    -- Makes the (deprecated) usage of * instead of Data.Kind.Type an error
+    NoStarIsType
+
+    -- Convenient and crucial to deal with ambiguous field names, commonly
+    -- known as RecordDotSyntax
+    OverloadedRecordDot
+
+    -- does not export record fields as functions, use OverloadedRecordDot to access instead
+    NoFieldSelectors
+
+    -- Record punning
+    RecordWildCards
+
+    -- Improved Deriving
+    DerivingStrategies
+    DerivingVia
+
+    -- Type-level strings
+    DataKinds
+
+    -- to enable the `type` keyword in import lists (ormolu uses this automatically)
+    ExplicitNamespaces
+
+  default-language: GHC2021
+
+
+library
+    import: common-options
+    exposed-modules:
+        Netencode,
+        Netencode.Parse
+
+    build-depends:
+        base >=4.15 && <5,
+        pa-prelude,
+        pa-label,
+        pa-error-tree,
+        hedgehog,
+        nonempty-containers,
+        deriving-compat,
+        data-fix,
+        bytestring,
+        attoparsec,
+        text,
+        semigroupoids,
+        selective
diff --git a/users/Profpatsch/netencode/netencode.rs b/users/Profpatsch/netencode/netencode.rs
index fcf642ca02..34a8fcef09 100644
--- a/users/Profpatsch/netencode/netencode.rs
+++ b/users/Profpatsch/netencode/netencode.rs
@@ -1,9 +1,9 @@
-extern crate nom;
 extern crate exec_helpers;
+extern crate nom;
 
 use std::collections::HashMap;
-use std::io::{Write, Read};
-use std::fmt::{Display, Debug};
+use std::fmt::{Debug, Display};
+use std::io::{Read, Write};
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum T {
@@ -46,22 +46,19 @@ impl T {
             T::I7(i) => U::I7(*i),
             T::Text(t) => U::Text(t.as_str()),
             T::Binary(v) => U::Binary(v),
-            T::Sum(Tag { tag, val }) => U::Sum(
-                Tag { tag: tag.as_str(), val: Box::new(val.to_u()) }
-            ),
-            T::Record(map) => U::Record(
-                map.iter().map(|(k, v)| (k.as_str(), v.to_u())).collect()
-            ),
-            T::List(l) => U::List(
-                l.iter().map(|v| v.to_u()).collect::<Vec<U<'a>>>()
-            ),
+            T::Sum(Tag { tag, val }) => U::Sum(Tag {
+                tag: tag.as_str(),
+                val: Box::new(val.to_u()),
+            }),
+            T::Record(map) => U::Record(map.iter().map(|(k, v)| (k.as_str(), v.to_u())).collect()),
+            T::List(l) => U::List(l.iter().map(|v| v.to_u()).collect::<Vec<U<'a>>>()),
         }
     }
 
     pub fn encode<'a>(&'a self) -> Vec<u8> {
         match self {
             // TODO: don’t go via U, inefficient
-            o => o.to_u().encode()
+            o => o.to_u().encode(),
         }
     }
 }
@@ -110,15 +107,16 @@ impl<'a> U<'a> {
             U::I7(i) => T::I7(*i),
             U::Text(t) => T::Text((*t).to_owned()),
             U::Binary(v) => T::Binary((*v).to_owned()),
-            U::Sum(Tag { tag, val }) => T::Sum(
-                Tag { tag: (*tag).to_owned(), val: Box::new(val.to_t()) }
-            ),
+            U::Sum(Tag { tag, val }) => T::Sum(Tag {
+                tag: (*tag).to_owned(),
+                val: Box::new(val.to_t()),
+            }),
             U::Record(map) => T::Record(
-                map.iter().map(|(k, v)| ((*k).to_owned(), v.to_t())).collect::<HashMap<String, T>>()
-            ),
-            U::List(l) => T::List(
-                l.iter().map(|v| v.to_t()).collect::<Vec<T>>()
+                map.iter()
+                    .map(|(k, v)| ((*k).to_owned(), v.to_t()))
+                    .collect::<HashMap<String, T>>(),
             ),
+            U::List(l) => T::List(l.iter().map(|v| v.to_t()).collect::<Vec<T>>()),
         }
     }
 }
@@ -127,16 +125,18 @@ impl<'a> U<'a> {
 pub struct Tag<S, A> {
     // TODO: make into &str
     pub tag: S,
-    pub val: Box<A>
+    pub val: Box<A>,
 }
 
 impl<S, A> Tag<S, A> {
     fn map<F, B>(self, f: F) -> Tag<S, B>
-        where F: Fn(A) -> B {
-          Tag {
-              tag: self.tag,
-              val: Box::new(f(*self.val))
-          }
+    where
+        F: Fn(A) -> B,
+    {
+        Tag {
+            tag: self.tag,
+            val: Box::new(f(*self.val)),
+        }
     }
 }
 
@@ -147,77 +147,170 @@ fn encode_tag<W: Write>(w: &mut W, tag: &str, val: &U) -> std::io::Result<()> {
 }
 
 pub fn encode<W: Write>(w: &mut W, u: &U) -> std::io::Result<()> {
-  match u {
-      U::Unit => write!(w, "u,"),
-      U::N1(b) => if *b { write!(w, "n1:1,") } else { write!(w, "n1:0,") },
-      U::N3(n) => write!(w, "n3:{},", n),
-      U::N6(n) => write!(w, "n6:{},", n),
-      U::N7(n) => write!(w, "n7:{},", n),
-      U::I3(i) => write!(w, "i3:{},", i),
-      U::I6(i) => write!(w, "i6:{},", i),
-      U::I7(i) => write!(w, "i7:{},", i),
-      U::Text(s) => {
-          write!(w, "t{}:", s.len());
-          w.write_all(s.as_bytes());
-          write!(w, ",")
-      }
-      U::Binary(s) => {
-          write!(w, "b{}:", s.len());
-          w.write_all(&s);
-          write!(w, ",")
-      },
-      U::Sum(Tag{tag, val}) => encode_tag(w, tag, val),
-      U::Record(m) => {
-          let mut c = std::io::Cursor::new(vec![]);
-          for (k, v) in m {
-              encode_tag(&mut c, k, v)?;
-          }
-          write!(w, "{{{}:", c.get_ref().len())?;
-          w.write_all(c.get_ref())?;
-          write!(w, "}}")
-      },
-      U::List(l) => {
-          let mut c = std::io::Cursor::new(vec![]);
-          for u in l {
-              encode(&mut c, u)?;
-          }
-          write!(w, "[{}:", c.get_ref().len())?;
-          w.write_all(c.get_ref())?;
-          write!(w, "]")
-      }
-  }
+    match u {
+        U::Unit => write!(w, "u,"),
+        U::N1(b) => {
+            if *b {
+                write!(w, "n1:1,")
+            } else {
+                write!(w, "n1:0,")
+            }
+        }
+        U::N3(n) => write!(w, "n3:{},", n),
+        U::N6(n) => write!(w, "n6:{},", n),
+        U::N7(n) => write!(w, "n7:{},", n),
+        U::I3(i) => write!(w, "i3:{},", i),
+        U::I6(i) => write!(w, "i6:{},", i),
+        U::I7(i) => write!(w, "i7:{},", i),
+        U::Text(s) => {
+            write!(w, "t{}:", s.len());
+            w.write_all(s.as_bytes());
+            write!(w, ",")
+        }
+        U::Binary(s) => {
+            write!(w, "b{}:", s.len());
+            w.write_all(&s);
+            write!(w, ",")
+        }
+        U::Sum(Tag { tag, val }) => encode_tag(w, tag, val),
+        U::Record(m) => {
+            let mut c = std::io::Cursor::new(vec![]);
+            for (k, v) in m {
+                encode_tag(&mut c, k, v)?;
+            }
+            write!(w, "{{{}:", c.get_ref().len())?;
+            w.write_all(c.get_ref())?;
+            write!(w, "}}")
+        }
+        U::List(l) => {
+            let mut c = std::io::Cursor::new(vec![]);
+            for u in l {
+                encode(&mut c, u)?;
+            }
+            write!(w, "[{}:", c.get_ref().len())?;
+            w.write_all(c.get_ref())?;
+            write!(w, "]")
+        }
+    }
 }
 
 pub fn text(s: String) -> T {
     T::Text(s)
 }
 
-pub fn u_from_stdin_or_die_user_error<'a>(prog_name: &'_ str, stdin_buf: &'a mut Vec<u8>) -> U<'a> {
-    std::io::stdin().lock().read_to_end(stdin_buf);
-    let u = match parse::u_u(stdin_buf) {
-        Ok((rest, u)) => match rest {
-            b"" => u,
-            _ => exec_helpers::die_user_error(prog_name, format!("stdin contained some soup after netencode value: {:?}", String::from_utf8_lossy(rest)))
-        },
-        Err(err) => exec_helpers::die_user_error(prog_name, format!("unable to parse netencode from stdin: {:?}", err))
-    };
-    u
+pub fn t_from_stdin_or_die_user_error<'a>(prog_name: &'_ str) -> T {
+    match t_from_stdin_or_die_user_error_with_rest(prog_name, &vec![]) {
+        None => exec_helpers::die_user_error(prog_name, "stdin was empty"),
+        Some((rest, t)) => {
+            if rest.is_empty() {
+                t
+            } else {
+                exec_helpers::die_user_error(
+                    prog_name,
+                    format!(
+                        "stdin contained some soup after netencode value: {:?}",
+                        String::from_utf8_lossy(&rest)
+                    ),
+                )
+            }
+        }
+    }
+}
+
+/// Read a netencode value from stdin incrementally, return bytes that could not be read.
+/// Nothing if there was nothing to read from stdin & no initial_bytes were provided.
+/// These can be passed back as `initial_bytes` if more values should be read.
+pub fn t_from_stdin_or_die_user_error_with_rest<'a>(
+    prog_name: &'_ str,
+    initial_bytes: &[u8],
+) -> Option<(Vec<u8>, T)> {
+    let mut chonker = Chunkyboi::new(std::io::stdin().lock(), 4096);
+    // The vec to pass to the parser on each step
+    let mut parser_vec: Vec<u8> = initial_bytes.to_vec();
+    // whether stdin was already empty
+    let mut was_empty: bool = false;
+    loop {
+        match chonker.next() {
+            None => {
+                if parser_vec.is_empty() {
+                    return None;
+                } else {
+                    was_empty = true
+                }
+            }
+            Some(Err(err)) => exec_helpers::die_temporary(
+                prog_name,
+                &format!("could not read from stdin: {:?}", err),
+            ),
+            Some(Ok(mut new_bytes)) => parser_vec.append(&mut new_bytes),
+        }
+
+        match parse::t_t(&parser_vec) {
+            Ok((rest, t)) => return Some((rest.to_owned(), t)),
+            Err(nom::Err::Incomplete(Needed)) => {
+                if was_empty {
+                    exec_helpers::die_user_error(
+                        prog_name,
+                        &format!(
+                            "unable to parse netencode from stdin, input incomplete: {:?}",
+                            parser_vec
+                        ),
+                    );
+                }
+                // read more from stdin and try parsing again
+                continue;
+            }
+            Err(err) => exec_helpers::die_user_error(
+                prog_name,
+                &format!("unable to parse netencode from stdin: {:?}", err),
+            ),
+        }
+    }
+}
+
+// iter helper
+// TODO: put into its own module
+struct Chunkyboi<T> {
+    inner: T,
+    buf: Vec<u8>,
+}
+
+impl<R: Read> Chunkyboi<R> {
+    fn new(inner: R, chunksize: usize) -> Self {
+        let buf = vec![0; chunksize];
+        Chunkyboi { inner, buf }
+    }
+}
+
+impl<R: Read> Iterator for Chunkyboi<R> {
+    type Item = std::io::Result<Vec<u8>>;
+
+    fn next(&mut self) -> Option<std::io::Result<Vec<u8>>> {
+        match self.inner.read(&mut self.buf) {
+            Ok(0) => None,
+            Ok(read) => {
+                // clone a new buffer so we can reuse the internal one
+                Some(Ok(self.buf[..read].to_owned()))
+            }
+            Err(err) => Some(Err(err)),
+        }
+    }
 }
 
 pub mod parse {
-    use super::{T, Tag, U};
+    use super::{Tag, T, U};
 
-    use std::str::FromStr;
-    use std::ops::Neg;
     use std::collections::HashMap;
+    use std::ops::Neg;
+    use std::str::FromStr;
 
-    use nom::{IResult};
-    use nom::branch::{alt};
+    use nom::branch::alt;
     use nom::bytes::streaming::{tag, take};
-    use nom::character::streaming::{digit1, char};
-    use nom::sequence::{tuple};
-    use nom::combinator::{map, map_res, flat_map, map_parser, opt};
+    use nom::character::streaming::{char, digit1};
+    use nom::combinator::{flat_map, map, map_parser, map_res, opt};
     use nom::error::{context, ErrorKind, ParseError};
+    use nom::sequence::tuple;
+    use nom::IResult;
 
     fn unit_t(s: &[u8]) -> IResult<&[u8], ()> {
         let (s, _) = context("unit", tag("u,"))(s)?;
@@ -227,9 +320,9 @@ pub mod parse {
     fn usize_t(s: &[u8]) -> IResult<&[u8], usize> {
         context(
             "usize",
-            map_res(
-                map_res(digit1, |n| std::str::from_utf8(n)),
-                |s| s.parse::<usize>())
+            map_res(map_res(digit1, |n| std::str::from_utf8(n)), |s| {
+                s.parse::<usize>()
+            }),
         )(s)
     }
 
@@ -238,87 +331,77 @@ pub mod parse {
             // This is the point where we check the descriminator;
             // if the beginning char does not match, we can immediately return.
             let (s, _) = char(begin)(s)?;
-            let (s, (len, _)) = tuple((
-                usize_t,
-                char(':')
-            ))(s)?;
-            let (s, (res, _)) = tuple((
-                take(len),
-                char(end)
-            ))(s)?;
+            let (s, (len, _)) = tuple((usize_t, char(':')))(s)?;
+            let (s, (res, _)) = tuple((take(len), char(end)))(s)?;
             Ok((s, res))
         }
     }
 
-
     fn uint_t<'a, I: FromStr + 'a>(t: &'static str) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], I> {
         move |s: &'a [u8]| {
             let (s, (_, _, int, _)) = tuple((
                 tag(t.as_bytes()),
                 char(':'),
-                map_res(
-                    map_res(digit1, |n: &[u8]| std::str::from_utf8(n)),
-                    |s| s.parse::<I>()
-                ),
-                char(',')
+                map_res(map_res(digit1, |n: &[u8]| std::str::from_utf8(n)), |s| {
+                    s.parse::<I>()
+                }),
+                char(','),
             ))(s)?;
             Ok((s, int))
         }
     }
 
     fn bool_t<'a>() -> impl Fn(&'a [u8]) -> IResult<&'a [u8], bool> {
-        context("bool", alt((
-            map(tag("n1:0,"), |_| false),
-            map(tag("n1:1,"), |_| true),
-        )))
-    }
-
-    fn int_t<'a, I: FromStr + Neg<Output=I>>(t: &'static str) -> impl Fn(&'a [u8]) -> IResult<&[u8], I> {
         context(
-            t,
-            move |s: &'a [u8]| {
-                let (s, (_, _, neg, int, _)) = tuple((
-                    tag(t.as_bytes()),
-                    char(':'),
-                    opt(char('-')),
-                    map_res(
-                        map_res(digit1, |n: &[u8]| std::str::from_utf8(n)),
-                        |s| s.parse::<I>()
-                    ),
-                    char(',')
-                ))(s)?;
-                let res = match neg {
-                    Some(_) => -int,
-                    None => int,
-                };
-                Ok((s, res))
-            }
+            "bool",
+            alt((map(tag("n1:0,"), |_| false), map(tag("n1:1,"), |_| true))),
         )
     }
 
+    fn int_t<'a, I: FromStr + Neg<Output = I>>(
+        t: &'static str,
+    ) -> impl Fn(&'a [u8]) -> IResult<&[u8], I> {
+        context(t, move |s: &'a [u8]| {
+            let (s, (_, _, neg, int, _)) = tuple((
+                tag(t.as_bytes()),
+                char(':'),
+                opt(char('-')),
+                map_res(map_res(digit1, |n: &[u8]| std::str::from_utf8(n)), |s| {
+                    s.parse::<I>()
+                }),
+                char(','),
+            ))(s)?;
+            let res = match neg {
+                Some(_) => -int,
+                None => int,
+            };
+            Ok((s, res))
+        })
+    }
+
     fn tag_t(s: &[u8]) -> IResult<&[u8], Tag<String, T>> {
         // recurses into the main parser
-        map(tag_g(t_t),
-            |Tag {tag, val}|
-            Tag {
-                tag: tag.to_string(),
-                val
-            })(s)
+        map(tag_g(t_t), |Tag { tag, val }| Tag {
+            tag: tag.to_string(),
+            val,
+        })(s)
     }
 
     fn tag_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], Tag<&'a str, O>>
     where
-        P: Fn(&'a [u8]) -> IResult<&'a [u8], O>
+        P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
     {
         move |s: &[u8]| {
             let (s, tag) = sized('<', '|')(s)?;
             let (s, val) = inner(s)?;
-            Ok((s, Tag {
-                tag: std::str::from_utf8(tag)
-                    .map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
-                val: Box::new(val)
-            }))
-
+            Ok((
+                s,
+                Tag {
+                    tag: std::str::from_utf8(tag)
+                        .map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
+                    val: Box::new(val),
+                },
+            ))
         }
     }
 
@@ -330,9 +413,9 @@ pub mod parse {
 
     fn text_g(s: &[u8]) -> IResult<&[u8], &str> {
         let (s, res) = sized('t', ',')(s)?;
-        Ok((s,
-            std::str::from_utf8(res)
-                .map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
+        Ok((
+            s,
+            std::str::from_utf8(res).map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
         ))
     }
 
@@ -374,22 +457,24 @@ pub mod parse {
     {
         map_parser(
             sized('[', ']'),
-            nom::multi::many0(inner_no_empty_string(inner))
+            nom::multi::many0(inner_no_empty_string(inner)),
         )
     }
 
     fn record_t<'a>(s: &'a [u8]) -> IResult<&'a [u8], HashMap<String, T>> {
         let (s, r) = record_g(t_t)(s)?;
-        Ok((s,
+        Ok((
+            s,
             r.into_iter()
-            .map(|(k, v)| (k.to_string(), v))
-            .collect::<HashMap<_,_>>()))
+                .map(|(k, v)| (k.to_string(), v))
+                .collect::<HashMap<_, _>>(),
+        ))
     }
 
     fn record_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], HashMap<&'a str, O>>
     where
         O: Clone,
-        P: Fn(&'a [u8]) -> IResult<&'a [u8], O>
+        P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
     {
         move |s: &'a [u8]| {
             let (s, map) = map_parser(
@@ -397,19 +482,17 @@ pub mod parse {
                 nom::multi::fold_many0(
                     inner_no_empty_string(tag_g(&inner)),
                     HashMap::new(),
-                    |mut acc: HashMap<_,_>, Tag { tag, mut val }| {
-                        // ignore duplicated tag names that appear later
+                    |mut acc: HashMap<_, _>, Tag { tag, mut val }| {
+                        // ignore earlier tags with the same name
                         // according to netencode spec
-                        if ! acc.contains_key(tag) {
-                            acc.insert(tag, *val);
-                        }
+                        let _ = acc.insert(tag, *val);
                         acc
-                    }
-                )
+                    },
+                ),
             )(s)?;
             if map.is_empty() {
                 // records must not be empty, according to the spec
-                Err(nom::Err::Failure((s,nom::error::ErrorKind::Many1)))
+                Err(nom::Err::Failure((s, nom::error::ErrorKind::Many1)))
             } else {
                 Ok((s, map))
             }
@@ -424,7 +507,6 @@ pub mod parse {
             map(tag_g(u_u), |t| U::Sum(t)),
             map(list_g(u_u), U::List),
             map(record_g(u_u), U::Record),
-
             map(bool_t(), |u| U::N1(u)),
             map(uint_t("n3"), |u| U::N3(u)),
             map(uint_t("n6"), |u| U::N6(u)),
@@ -432,7 +514,6 @@ pub mod parse {
             map(int_t("i3"), |u| U::I3(u)),
             map(int_t("i6"), |u| U::I6(u)),
             map(int_t("i7"), |u| U::I7(u)),
-
             // less common
             map(uint_t("n2"), |u| U::N3(u)),
             map(uint_t("n4"), |u| U::N6(u)),
@@ -445,7 +526,7 @@ pub mod parse {
         ))(s)
     }
 
-    pub fn t_t(s: &[u8]) -> IResult<&[u8], T>  {
+    pub fn t_t(s: &[u8]) -> IResult<&[u8], T> {
         alt((
             text,
             binary(),
@@ -453,7 +534,6 @@ pub mod parse {
             map(tag_t, |t| T::Sum(t)),
             map(list_t, |l| T::List(l)),
             map(record_t, |p| T::Record(p)),
-
             map(bool_t(), |u| T::N1(u)),
             // 8, 64 and 128 bit
             map(uint_t("n3"), |u| T::N3(u)),
@@ -462,7 +542,6 @@ pub mod parse {
             map(int_t("i3"), |u| T::I3(u)),
             map(int_t("i6"), |u| T::I6(u)),
             map(int_t("i7"), |u| T::I7(u)),
-
             // less common
             map(uint_t("n2"), |u| T::N3(u)),
             map(uint_t("n4"), |u| T::N6(u)),
@@ -481,30 +560,18 @@ pub mod parse {
 
         #[test]
         fn test_parse_unit_t() {
-            assert_eq!(
-                unit_t("u,".as_bytes()),
-                Ok(("".as_bytes(), ()))
-            );
+            assert_eq!(unit_t("u,".as_bytes()), Ok(("".as_bytes(), ())));
         }
 
         #[test]
         fn test_parse_bool_t() {
-            assert_eq!(
-                bool_t()("n1:0,".as_bytes()),
-                Ok(("".as_bytes(), false))
-            );
-            assert_eq!(
-                bool_t()("n1:1,".as_bytes()),
-                Ok(("".as_bytes(), true))
-            );
+            assert_eq!(bool_t()("n1:0,".as_bytes()), Ok(("".as_bytes(), false)));
+            assert_eq!(bool_t()("n1:1,".as_bytes()), Ok(("".as_bytes(), true)));
         }
 
         #[test]
         fn test_parse_usize_t() {
-            assert_eq!(
-                usize_t("32foo".as_bytes()),
-                Ok(("foo".as_bytes(), 32))
-            );
+            assert_eq!(usize_t("32foo".as_bytes()), Ok(("foo".as_bytes(), 32)));
         }
 
         #[test]
@@ -515,7 +582,10 @@ pub mod parse {
             );
             assert_eq!(
                 uint_t::<u8>("n3")("n3:1024,abc".as_bytes()),
-                Err(nom::Err::Error(("1024,abc".as_bytes(), nom::error::ErrorKind::MapRes)))
+                Err(nom::Err::Error((
+                    "1024,abc".as_bytes(),
+                    nom::error::ErrorKind::MapRes
+                )))
             );
             assert_eq!(
                 int_t::<i64>("i6")("i6:-23,abc".as_bytes()),
@@ -544,18 +614,21 @@ pub mod parse {
             assert_eq!(
                 text("t5:hello,".as_bytes()),
                 Ok(("".as_bytes(), T::Text("hello".to_owned()))),
-                "{}", r"t5:hello,"
+                "{}",
+                r"t5:hello,"
             );
             assert_eq!(
                 text("t4:fo".as_bytes()),
                 // The content of the text should be 4 long
                 Err(nom::Err::Incomplete(nom::Needed::Size(4))),
-                "{}", r"t4:fo,"
+                "{}",
+                r"t4:fo,"
             );
             assert_eq!(
                 text("t9:今日は,".as_bytes()),
                 Ok(("".as_bytes(), T::Text("今日は".to_owned()))),
-                "{}", r"t9:今日は,"
+                "{}",
+                r"t9:今日は,"
             );
         }
 
@@ -564,24 +637,28 @@ pub mod parse {
             assert_eq!(
                 binary()("b5:hello,".as_bytes()),
                 Ok(("".as_bytes(), T::Binary(Vec::from("hello".to_owned())))),
-                "{}", r"b5:hello,"
+                "{}",
+                r"b5:hello,"
             );
             assert_eq!(
                 binary()("b4:fo".as_bytes()),
                 // The content of the byte should be 4 long
                 Err(nom::Err::Incomplete(nom::Needed::Size(4))),
-                "{}", r"b4:fo,"
+                "{}",
+                r"b4:fo,"
             );
             assert_eq!(
                 binary()("b4:foob".as_bytes()),
                 // The content is 4 bytes now, but the finishing , is missing
                 Err(nom::Err::Incomplete(nom::Needed::Size(1))),
-                    "{}", r"b4:fo,"
-                );
+                "{}",
+                r"b4:fo,"
+            );
             assert_eq!(
                 binary()("b9:今日は,".as_bytes()),
                 Ok(("".as_bytes(), T::Binary(Vec::from("今日は".as_bytes())))),
-                "{}", r"b9:今日は,"
+                "{}",
+                r"b9:今日は,"
             );
         }
 
@@ -590,25 +667,23 @@ pub mod parse {
             assert_eq!(
                 list_t("[0:]".as_bytes()),
                 Ok(("".as_bytes(), vec![])),
-                "{}", r"[0:]"
+                "{}",
+                r"[0:]"
             );
             assert_eq!(
                 list_t("[6:u,u,u,]".as_bytes()),
-                Ok(("".as_bytes(), vec![
-                    T::Unit,
-                    T::Unit,
-                    T::Unit,
-                ])),
-                "{}", r"[6:u,u,u,]"
+                Ok(("".as_bytes(), vec![T::Unit, T::Unit, T::Unit,])),
+                "{}",
+                r"[6:u,u,u,]"
             );
             assert_eq!(
                 list_t("[15:u,[7:t3:foo,]u,]".as_bytes()),
-                Ok(("".as_bytes(), vec![
-                    T::Unit,
-                    T::List(vec![T::Text("foo".to_owned())]),
-                    T::Unit,
-                ])),
-                "{}", r"[15:u,[7:t3:foo,]u,]"
+                Ok((
+                    "".as_bytes(),
+                    vec![T::Unit, T::List(vec![T::Text("foo".to_owned())]), T::Unit,]
+                )),
+                "{}",
+                r"[15:u,[7:t3:foo,]u,]"
             );
         }
 
@@ -616,27 +691,40 @@ pub mod parse {
         fn test_record() {
             assert_eq!(
                 record_t("{21:<1:a|u,<1:b|u,<1:c|u,}".as_bytes()),
-                Ok(("".as_bytes(), vec![
-                    ("a".to_owned(), T::Unit),
-                    ("b".to_owned(), T::Unit),
-                    ("c".to_owned(), T::Unit),
-                ].into_iter().collect::<HashMap<String, T>>())),
-                "{}", r"{21:<1:a|u,<1:b|u,<1:c|u,}"
+                Ok((
+                    "".as_bytes(),
+                    vec![
+                        ("a".to_owned(), T::Unit),
+                        ("b".to_owned(), T::Unit),
+                        ("c".to_owned(), T::Unit),
+                    ]
+                    .into_iter()
+                    .collect::<HashMap<String, T>>()
+                )),
+                "{}",
+                r"{21:<1:a|u,<1:b|u,<1:c|u,}"
             );
             // duplicated keys are ignored (first is taken)
             assert_eq!(
                 record_t("{25:<1:a|u,<1:b|u,<1:a|i1:-1,}".as_bytes()),
-                Ok(("".as_bytes(), vec![
-                    ("a".to_owned(), T::Unit),
-                    ("b".to_owned(), T::Unit),
-                ].into_iter().collect::<HashMap<_,_>>())),
-                "{}", r"{25:<1:a|u,<1:b|u,<1:a|i1:-1,}"
+                Ok((
+                    "".as_bytes(),
+                    vec![("a".to_owned(), T::I3(-1)), ("b".to_owned(), T::Unit),]
+                        .into_iter()
+                        .collect::<HashMap<_, _>>()
+                )),
+                "{}",
+                r"{25:<1:a|u,<1:b|u,<1:a|i1:-1,}"
             );
             // empty records are not allowed
             assert_eq!(
                 record_t("{0:}".as_bytes()),
-                Err(nom::Err::Failure(("".as_bytes(), nom::error::ErrorKind::Many1))),
-                "{}", r"{0:}"
+                Err(nom::Err::Failure((
+                    "".as_bytes(),
+                    nom::error::ErrorKind::Many1
+                ))),
+                "{}",
+                r"{0:}"
             );
         }
 
@@ -645,37 +733,62 @@ pub mod parse {
             assert_eq!(
                 t_t("n3:255,".as_bytes()),
                 Ok(("".as_bytes(), T::N3(255))),
-                "{}", r"n3:255,"
+                "{}",
+                r"n3:255,"
             );
             assert_eq!(
                 t_t("t6:halloo,".as_bytes()),
                 Ok(("".as_bytes(), T::Text("halloo".to_owned()))),
-                "{}", r"t6:halloo,"
+                "{}",
+                r"t6:halloo,"
             );
             assert_eq!(
                 t_t("<3:foo|t6:halloo,".as_bytes()),
-                Ok(("".as_bytes(), T::Sum (Tag {
-                    tag: "foo".to_owned(),
-                    val: Box::new(T::Text("halloo".to_owned()))
-                }))),
-                "{}", r"<3:foo|t6:halloo,"
+                Ok((
+                    "".as_bytes(),
+                    T::Sum(Tag {
+                        tag: "foo".to_owned(),
+                        val: Box::new(T::Text("halloo".to_owned()))
+                    })
+                )),
+                "{}",
+                r"<3:foo|t6:halloo,"
             );
             // { a: Unit
             // , foo: List <A: Unit | B: List i3> }
             assert_eq!(
                 t_t("{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}".as_bytes()),
-                Ok(("".as_bytes(), T::Record(vec![
-                    ("a".to_owned(), T::Unit),
-                    ("foo".to_owned(), T::List(vec![
-                        T::Sum(Tag { tag: "A".to_owned(), val: Box::new(T::Unit) }),
-                        T::Sum(Tag { tag: "A".to_owned(), val: Box::new(T::N1(true)) }),
-                        T::Sum(Tag { tag: "B".to_owned(), val: Box::new(T::List(vec![T::I3(127)])) }),
-                    ]))
-                ].into_iter().collect::<HashMap<String, T>>()))),
-                "{}", r"{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}"
+                Ok((
+                    "".as_bytes(),
+                    T::Record(
+                        vec![
+                            ("a".to_owned(), T::Unit),
+                            (
+                                "foo".to_owned(),
+                                T::List(vec![
+                                    T::Sum(Tag {
+                                        tag: "A".to_owned(),
+                                        val: Box::new(T::Unit)
+                                    }),
+                                    T::Sum(Tag {
+                                        tag: "A".to_owned(),
+                                        val: Box::new(T::N1(true))
+                                    }),
+                                    T::Sum(Tag {
+                                        tag: "B".to_owned(),
+                                        val: Box::new(T::List(vec![T::I3(127)]))
+                                    }),
+                                ])
+                            )
+                        ]
+                        .into_iter()
+                        .collect::<HashMap<String, T>>()
+                    )
+                )),
+                "{}",
+                r"{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}"
             );
         }
-
     }
 }
 
@@ -690,8 +803,10 @@ pub mod dec {
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError>;
     }
 
+    /// Any netencode, as `T`.
     #[derive(Clone, Copy)]
     pub struct AnyT;
+    /// Any netencode, as `U`.
     #[derive(Clone, Copy)]
     pub struct AnyU;
 
@@ -709,8 +824,11 @@ pub mod dec {
         }
     }
 
+    /// A text
     #[derive(Clone, Copy)]
     pub struct Text;
+
+    /// A bytestring
     // TODO: rename to Bytes
     #[derive(Clone, Copy)]
     pub struct Binary;
@@ -730,11 +848,15 @@ pub mod dec {
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
             match u {
                 U::Binary(b) => Ok(b),
-                other => Err(DecodeError(format!("Cannot decode {:?} into Binary", other))),
+                other => Err(DecodeError(format!(
+                    "Cannot decode {:?} into Binary",
+                    other
+                ))),
             }
         }
     }
 
+    /// Any scalar, converted to bytes.
     #[derive(Clone, Copy)]
     pub struct ScalarAsBytes;
 
@@ -755,80 +877,93 @@ pub mod dec {
         }
     }
 
+    /// A map of Ts (TODO: rename to map)
     #[derive(Clone, Copy)]
     pub struct Record<T>(pub T);
 
     impl<'a, Inner> Decoder<'a> for Record<Inner>
-        where Inner: Decoder<'a>
+    where
+        Inner: Decoder<'a>,
     {
         type A = HashMap<&'a str, Inner::A>;
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
             match u {
-                U::Record(map) =>
-                    map.into_iter()
+                U::Record(map) => map
+                    .into_iter()
                     .map(|(k, v)| self.0.dec(v).map(|v2| (k, v2)))
                     .collect::<Result<Self::A, _>>(),
-                o => Err(DecodeError(format!("Cannot decode {:?} into record", o)))
+                o => Err(DecodeError(format!("Cannot decode {:?} into record", o))),
             }
         }
     }
 
+    /// Assume a record and project out the field with the given name and type.
     #[derive(Clone, Copy)]
     pub struct RecordDot<'a, T> {
         pub field: &'a str,
-        pub inner: T
+        pub inner: T,
     }
 
-    impl <'a, Inner> Decoder<'a> for RecordDot<'_, Inner>
-        where Inner: Decoder<'a> + Clone
+    impl<'a, Inner> Decoder<'a> for RecordDot<'_, Inner>
+    where
+        Inner: Decoder<'a> + Clone,
     {
         type A = Inner::A;
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
             match Record(self.inner.clone()).dec(u) {
                 Ok(mut map) => match map.remove(self.field) {
                     Some(inner) => Ok(inner),
-                    None => Err(DecodeError(format!("Cannot find `{}` in record map", self.field))),
+                    None => Err(DecodeError(format!(
+                        "Cannot find `{}` in record map",
+                        self.field
+                    ))),
                 },
                 Err(err) => Err(err),
             }
         }
     }
 
+    /// Equals one of the listed `A`s exactly, after decoding.
     #[derive(Clone)]
-    pub struct OneOf<T, A>{
+    pub struct OneOf<T, A> {
         pub inner: T,
         pub list: Vec<A>,
     }
 
-    impl <'a, Inner> Decoder<'a> for OneOf<Inner, Inner::A>
-        where Inner: Decoder<'a>,
-              Inner::A: Display + Debug + PartialEq
+    impl<'a, Inner> Decoder<'a> for OneOf<Inner, Inner::A>
+    where
+        Inner: Decoder<'a>,
+        Inner::A: Display + Debug + PartialEq,
     {
         type A = Inner::A;
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
             match self.inner.dec(u) {
                 Ok(inner) => match self.list.iter().any(|x| x.eq(&inner)) {
                     true => Ok(inner),
-                    false => Err(DecodeError(format!("{} is not one of {:?}", inner, self.list)))
+                    false => Err(DecodeError(format!(
+                        "{} is not one of {:?}",
+                        inner, self.list
+                    ))),
                 },
-                Err(err) => Err(err)
+                Err(err) => Err(err),
             }
         }
     }
 
+    /// Try decoding as `T`.
     #[derive(Clone)]
     pub struct Try<T>(pub T);
 
-    impl <'a, Inner> Decoder<'a> for Try<Inner>
-        where Inner: Decoder<'a>
+    impl<'a, Inner> Decoder<'a> for Try<Inner>
+    where
+        Inner: Decoder<'a>,
     {
         type A = Option<Inner::A>;
         fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
             match self.0.dec(u) {
                 Ok(inner) => Ok(Some(inner)),
-                Err(err) => Ok(None)
+                Err(err) => Ok(None),
             }
         }
     }
-
 }
diff --git a/users/Profpatsch/netencode/pretty.rs b/users/Profpatsch/netencode/pretty.rs
index 8fec24a60e..935c3d4a8a 100644
--- a/users/Profpatsch/netencode/pretty.rs
+++ b/users/Profpatsch/netencode/pretty.rs
@@ -1,6 +1,6 @@
 extern crate netencode;
 
-use netencode::{U, T, Tag};
+use netencode::{Tag, T, U};
 
 pub enum Pretty {
     Single {
@@ -20,7 +20,7 @@ pub enum Pretty {
         r#type: char,
         length: String,
         vals: Vec<Pretty>,
-        trailer: char
+        trailer: char,
     },
 }
 
@@ -39,7 +39,7 @@ impl Pretty {
                 r#type: 't',
                 length: format!("{}:", s.len()),
                 val: s.to_string(),
-                trailer: ','
+                trailer: ',',
             },
             U::Binary(s) => Pretty::Single {
                 r#type: 'b',
@@ -47,15 +47,18 @@ impl Pretty {
                 // For pretty printing we want the string to be visible obviously.
                 // Instead of not supporting binary, let’s use lossy conversion.
                 val: String::from_utf8_lossy(s).into_owned(),
-                trailer: ','
+                trailer: ',',
             },
-            U::Sum(Tag{tag, val}) => Self::pretty_tag(tag, Self::from_u(*val)),
+            U::Sum(Tag { tag, val }) => Self::pretty_tag(tag, Self::from_u(*val)),
             U::Record(m) => Pretty::Multi {
                 r#type: '{',
                 // TODO: we are losing the size here, should we recompute it? Keep it?
                 length: String::from(""),
-                vals: m.into_iter().map(|(k, v)| Self::pretty_tag(k, Self::from_u(v))).collect(),
-                trailer: '}'
+                vals: m
+                    .into_iter()
+                    .map(|(k, v)| Self::pretty_tag(k, Self::from_u(v)))
+                    .collect(),
+                trailer: '}',
             },
             U::List(l) => Pretty::Multi {
                 r#type: '[',
@@ -68,13 +71,14 @@ impl Pretty {
     }
 
     fn scalar<D>(r#type: char, length: &str, d: D) -> Pretty
-    where D: std::fmt::Display
+    where
+        D: std::fmt::Display,
     {
         Pretty::Single {
             r#type,
             length: length.to_string(),
             val: format!("{}", d),
-            trailer: ','
+            trailer: ',',
         }
     }
 
@@ -89,43 +93,62 @@ impl Pretty {
     }
 
     pub fn print_multiline<W>(&self, mut w: &mut W) -> std::io::Result<()>
-        where W: std::io::Write
+    where
+        W: std::io::Write,
     {
         Self::go(&mut w, self, 0, true);
         write!(w, "\n")
     }
 
     fn go<W>(mut w: &mut W, p: &Pretty, depth: usize, is_newline: bool) -> std::io::Result<()>
-        where W: std::io::Write
+    where
+        W: std::io::Write,
     {
-        const full : usize = 4;
-        const half : usize = 2;
-        let i = &vec![b' '; depth*full];
-        let iandhalf = &vec![b' '; depth*full + half];
-        let (i, iandhalf) = unsafe {(
-            std::str::from_utf8_unchecked(i),
-            std::str::from_utf8_unchecked(iandhalf),
-        )};
+        const full: usize = 4;
+        const half: usize = 2;
+        let i = &vec![b' '; depth * full];
+        let iandhalf = &vec![b' '; depth * full + half];
+        let (i, iandhalf) = unsafe {
+            (
+                std::str::from_utf8_unchecked(i),
+                std::str::from_utf8_unchecked(iandhalf),
+            )
+        };
         if is_newline {
             write!(&mut w, "{}", i);
         }
         match p {
-            Pretty::Single {r#type, length, val, trailer} =>
-                write!(&mut w, "{} {}{}", r#type, val, trailer),
-            Pretty::Tag { r#type, length, key, inner, val } => {
+            Pretty::Single {
+                r#type,
+                length,
+                val,
+                trailer,
+            } => write!(&mut w, "{} {}{}", r#type, val, trailer),
+            Pretty::Tag {
+                r#type,
+                length,
+                key,
+                inner,
+                val,
+            } => {
                 write!(&mut w, "{} {} {}", r#type, key, inner)?;
                 Self::go::<W>(&mut w, val, depth, false)
-            },
+            }
             // if the length is 0 or 1, we print on one line,
             // only if there’s more than one element we split the resulting value.
             // we never break lines on arbitrary column sizes, since that is just silly.
-            Pretty::Multi {r#type, length, vals, trailer} => match vals.len() {
+            Pretty::Multi {
+                r#type,
+                length,
+                vals,
+                trailer,
+            } => match vals.len() {
                 0 => write!(&mut w, "{} {}", r#type, trailer),
                 1 => {
                     write!(&mut w, "{} ", r#type);
                     Self::go::<W>(&mut w, &vals[0], depth, false)?;
                     write!(&mut w, "{}", trailer)
-                },
+                }
                 more => {
                     write!(&mut w, "\n{}{} \n", iandhalf, r#type)?;
                     for v in vals {