Nix builtins

Nix has a lot of built-in functions, some of which are accessible in the global scope, and some of which are only accessible through the global builtins attribute set.

This document is an attempt to track all of these builtins, but without documenting their functionality.

The impl column indicates implementation status in tvix:

implemented: "" (empty cell)
not yet implemented, but not blocked: todo
not yet implemented, but blocked by other prerequisites:
- store: awaiting eval<->store api(s)
- context: awaiting support for string contexts

name	global	arity	pure	impl
abort	true	1
add	false	2	true
addErrorContext	false	?		context
all	false	2	true
any	false	2	true
appendContext	false	?		context
attrNames	false	1	true
attrValues	false		true
baseNameOf	true
bitAnd	false
bitOr	false
bitXor	false
builtins	true
catAttrs	false
compareVersions	false
concatLists	false
concatMap	false
concatStringsSep	false
currentSystem	false
currentTime	false		false
deepSeq	false
derivation	true			store
derivationStrict	true			store
dirOf	true
div	false
elem	false
elemAt	false
false	true
fetchGit	true			store
fetchMercurial	true			store
fetchTarball	true			store
fetchurl	false			store
filter	false
filterSource	false			store
findFile	false		false	todo
foldl'	false
fromJSON	false
fromTOML	true
functionArgs	false
genList	false
genericClosure	false			todo
getAttr	false
getContext	false
getEnv	false		false
hasAttr	false
hasContext	false
hashFile	false		false
hashString	false
head	false
import	true
intersectAttrs	false
isAttrs	false
isBool	false
isFloat	false
isFunction	false
isInt	false
isList	false
isNull	true
isPath	false
isString	false
langVersion	false
length	false
lessThan	false
listToAttrs	false
map	true
mapAttrs	false
match	false
mul	false
nixPath	false			todo
nixVersion	false			todo
null	true
parseDrvName	false
partition	false
path	false		sometimes	store
pathExists	false		false
placeholder	true			context
readDir	false		false
readFile	false		false
removeAttrs	true
replaceStrings	false
scopedImport	true
seq	false
sort	false
split	false
splitVersion	false
storeDir	false			store
storePath	false			store
stringLength	false
sub	false
substring	false
tail	false
throw	true
toFile	false			store
toJSON	false
toPath	false
toString	true
toXML	true
trace	false
true	true
tryEval	false
typeOf	false
unsafeDiscardOutputDependency	false
unsafeDiscardStringContext	false
unsafeGetAttrPos	false			todo
valueSize	false			todo

Added after C++ Nix 2.3 (without Flakes enabled)

name	global	arity	pure	impl
break	false	1		todo
ceil	false	1	true
fetchTree	true	1		todo
floor	false	1	true
groupBy	false	2	true
traceVerbose	false	2		todo
zipAttrsWith	false	2	true	todo