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-rw-r--r-- | users/Profpatsch/htmx-experiment/src/ValidationParseT.hs | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/users/Profpatsch/htmx-experiment/src/ValidationParseT.hs b/users/Profpatsch/htmx-experiment/src/ValidationParseT.hs new file mode 100644 index 000000000000..ffb6c2f395cb --- /dev/null +++ b/users/Profpatsch/htmx-experiment/src/ValidationParseT.hs @@ -0,0 +1,40 @@ +module ValidationParseT where + +import Control.Monad.Logger (MonadLogger) +import Control.Selective (Selective) +import Data.Error.Tree +import Data.Functor.Compose (Compose (..)) +import PossehlAnalyticsPrelude +import ServerErrors + +-- | A simple way to create an Applicative parser that parses from some environment. +-- +-- Use with DerivingVia. Grep codebase for examples. +newtype ValidationParseT env m a = ValidationParseT {unValidationParseT :: env -> m (Validation (NonEmpty Error) a)} + deriving + (Functor, Applicative, Selective) + via ( Compose + ((->) env) + (Compose m (Validation (NonEmpty Error))) + ) + +-- | Helper that runs the given parser and throws a user error if the parsing failed. +runValidationParseTOrUserError :: + forall validationParseT env m a. + ( Coercible validationParseT (ValidationParseT env m a), + MonadLogger m, + MonadThrow m + ) => + -- | toplevel error message to throw if the parsing fails + Error -> + -- | The parser which should be run + validationParseT -> + -- | input to the parser + env -> + m a +{-# INLINE runValidationParseTOrUserError #-} +runValidationParseTOrUserError contextError parser env = + (coerce @_ @(ValidationParseT _ _ _) parser).unValidationParseT env + >>= \case + Failure errs -> throwUserErrorTree (errorTree contextError errs) + Success a -> pure a |