stdlib-reference.md

id	stdlib-reference
title	Standard Library Signature Index
slug	/reference/stdlib

This is the complete catalog of core functions/values and default .NET runtime externs. Each name links to argument order, examples, and failure behavior. Type variables are local to each signature; repeated variables in a row must agree.

Core functions are always available. Runtime functions require host registration, are enabled by default in the CLI, and are disabled by --no-default-externs or runtime.default-externs = false. JavaScript hosts provide their own externs. Registered custom providers add functions beyond this standard catalog.

Top-level surface

Name	Type	Availability
ignore	'a -> unit	Core function; evaluates and discards its argument
Env	Environment	Value injected by CLI/REPL, optional in embedding hosts
Environment	{ ScriptName: string option; Arguments: string list }	Built-in record type
FsKind	File of string / Directory of string / Missing	Built-in union type

Core library

Bool

Name	Signature
Bool.toString	bool -> string
Bool.tryParse	string -> bool option

Float

Name	Signature
Float.toString	float -> string
Float.tryParse	string -> float option

Int

Name	Signature
Int.toString	int -> string
Int.tryParse	string -> int option

List

Name	Signature
List.append	'a list -> 'a list -> 'a list
List.choose	('a -> 'b option) -> 'a list -> 'b list
List.collect	('a -> 'b list) -> 'a list -> 'b list
List.contains	'a -> 'a list -> bool
List.distinct	'a list -> 'a list
List.empty	'a list
List.exists	('a -> bool) -> 'a list -> bool
List.filter	('a -> bool) -> 'a list -> 'a list
List.fold	('b -> 'a -> 'b) -> 'b -> 'a list -> 'b
List.iter	('a -> unit) -> 'a list -> unit
List.length	'a list -> int
List.map	('a -> 'b) -> 'a list -> 'b list
List.rev	'a list -> 'a list
List.tail	'a list -> 'a list
List.tryFind	('a -> bool) -> 'a list -> 'a option
List.tryGet	('a -> bool) -> 'a list -> int option
List.tryHead	'a list -> 'a option
List.tryItem	int -> 'a list -> 'a option

Map

Name	Signature
Map.add	'b -> 'a -> 'a map['b] -> 'a map['b]
Map.choose	('b -> 'a -> 'c option) -> 'a map['b] -> 'c map['b]
Map.containsKey	'b -> 'a map['b] -> bool
Map.count	'a map['b] -> int
Map.empty	'a map['b]
Map.filter	('b -> 'a -> bool) -> 'a map['b] -> 'a map['b]
Map.fold	('c -> 'b -> 'a -> 'c) -> 'c -> 'a map['b] -> 'c
Map.iter	('b -> 'a -> unit) -> 'a map['b] -> unit
Map.map	('a -> 'c) -> 'a map['b] -> 'c map['b]
Map.ofList	('b * 'a) list -> 'a map['b]
Map.remove	'b -> 'a map['b] -> 'a map['b]
Map.tryGet	'b -> 'a map['b] -> 'a option

Option

Name	Signature
Option.defaultValue	'a -> 'a option -> 'a
Option.defaultWith	(unit -> 'a) -> 'a option -> 'a
Option.isNone	'a option -> bool
Option.isSome	'a option -> bool
Option.map	('a -> 'b) -> 'a option -> 'b option

String

Name	Signature
String.concat	string -> string list -> string
String.endsWith	string -> string -> bool
String.indexOf	string -> string -> int option
String.replace	string -> string -> string -> string
String.split	string -> string -> string list
String.substring	int -> int -> string -> string option
String.toLower	string -> string
String.toUpper	string -> string

Default .NET runtime

Console

Name	Signature
Console.readLine	unit -> string option
Console.writeLine	string -> unit

Fs

Name	Signature
Fs.combinePath	string -> string -> string
Fs.createDirectory	string -> bool
Fs.enumerateFiles	string -> string -> string list option
Fs.exists	string -> bool
Fs.extension	string -> string option
Fs.fileNameWithoutExtension	string -> string
Fs.glob	string -> string list option
Fs.kind	string -> FsKind
Fs.parentDirectory	string -> string option
Fs.readText	string -> string option
Fs.writeText	string -> string -> bool

Guid

Name	Signature
Guid.new	'a -> string option

Hash

Name	Signature
Hash.md5	string -> string option

Json

Name	Signature
Json.deserialize	type -> string -> 'a option
Json.serialize	'a -> string option

Regex

Name	Signature
Regex.matchGroups	string -> string -> string list option

Task

Name	Signature
Task.spawn	(unit -> 'a) -> 'a task
Task.delay	int -> unit task
Task.fromResult	'a -> 'a task
Task.continueWith	('a -> 'b) -> 'a task -> 'b task
Task.whenAll	('a list -> 'b) -> 'a task list -> 'b task
Task.whenAny	('a -> 'b) -> 'a task list -> 'b task
Task.await	'a task -> 'a
Task.awaitAll	'a task list -> 'a list

Xml

Name	Signature
Xml.queryValues	string -> string -> string list option

Syntax and data forms

Constructors and syntax are separate from function registration: Some/None, union cases, literals, ranges, field access, list/map indexers, typeof, and nameof are covered in Native Types and Syntax and Operators. Host-provided type descriptors are covered in Host-Provided Types.

Json.deserialize uses a runtime type token; its generic result scheme does not statically encode the relationship between that token and the result. Guid.new accepts an ignored argument; use Guid.new (). List.contains compares scalars only; use List.exists with = for composite data.

Env.setExitCode : int -> unit selects the eventual shell status without stopping evaluation; see core builtins. It is effectful and accepts codes 0..255.

Expanded pure support library

Path, Glob, SemVer, scalar, and collection additions are core builtins. Encoding and SHA-256 are pure .NET runtime externs and need host registration. See each module for ordering, errors, and platform rules.

Int additions

Name	Signature
Int.abs	int -> int
Int.sign	int -> int
Int.min	int -> int -> int
Int.max	int -> int -> int
Int.clamp	int -> int -> int -> int
Int.toFloat	int -> float

Float additions

Name	Signature
Float.abs	float -> float
Float.sign	float -> int
Float.min	float -> float -> float
Float.max	float -> float -> float
Float.clamp	float -> float -> float -> float
Float.floor	float -> float
Float.ceil	float -> float
Float.round	float -> float
Float.truncate	float -> float
Float.sqrt	float -> float
Float.log	float -> float
Float.log10	float -> float
Float.exp	float -> float
Float.sin	float -> float
Float.cos	float -> float
Float.tan	float -> float
Float.asin	float -> float
Float.acos	float -> float
Float.atan	float -> float
Float.pow	float -> float -> float
Float.atan2	float -> float -> float
Float.isNaN	float -> bool
Float.isInfinity	float -> bool
Float.isFinite	float -> bool
Float.pi	float
Float.tryToInt	float -> int option

String additions

Name	Signature
String.compare	string -> string -> int
String.length	string -> int
String.isEmpty	string -> bool
String.isWhiteSpace	string -> bool
String.trim	string -> string
String.trimStart	string -> string
String.trimEnd	string -> string
String.splitLines	string -> string list
String.startsWith	string -> string -> bool
String.contains	string -> string -> bool
String.padLeft	int -> string -> string
String.padRight	int -> string -> string
String.repeat	int -> string -> string

List additions

Name	Signature
List.isEmpty	'a list -> bool
List.forall	('a -> bool) -> 'a list -> bool
List.mapi	(int -> 'a -> 'b) -> 'a list -> 'b list
List.indexed	'a list -> ((int * 'a)) list
List.init	int -> (int -> 'a) -> 'a list
List.take	int -> 'a list -> 'a list
List.skip	int -> 'a list -> 'a list
List.takeWhile	('a -> bool) -> 'a list -> 'a list
List.skipWhile	('a -> bool) -> 'a list -> 'a list
List.partition	('a -> bool) -> 'a list -> ('a list * 'a list)
List.zip	'a list -> 'b list -> (('a * 'b)) list
List.unzip	(('a * 'b)) list -> ('a list * 'b list)
List.chunkBySize	int -> 'a list -> 'a list list
List.scan	('d -> 'a -> 'd) -> 'd -> 'a list -> 'd list
List.sortWith	('a -> 'a -> int) -> 'a list -> 'a list
List.sortBy	('a -> 'c) -> 'a list -> 'a list
List.distinctBy	('a -> 'c) -> 'a list -> 'a list
List.groupBy	('a -> 'c) -> 'a list -> (('c * 'a list)) list
List.countBy	('a -> 'c) -> 'a list -> (('c * int)) list

Map additions

Name	Signature
Map.keys	'a map['c] -> 'c list
Map.values	'a map['c] -> 'a list
Map.toList	'a map['c] -> (('c * 'a)) list
Map.exists	('c -> 'a -> bool) -> 'a map['c] -> bool
Map.forall	('c -> 'a -> bool) -> 'a map['c] -> bool
Map.update	'c -> ('a option -> 'a option) -> 'a map['c] -> 'a map['c]
Map.mergeWith	('c -> 'a -> 'a -> 'a) -> 'a map['c] -> 'a map['c] -> 'a map['c]

Option additions

Name	Signature
Option.bind	('a -> 'b option) -> 'a option -> 'b option
Option.flatten	'a option option -> 'a option
Option.filter	('a -> bool) -> 'a option -> 'a option
Option.orElse	'a option -> 'a option -> 'a option
Option.orElseWith	(unit -> 'a option) -> 'a option -> 'a option
Option.map2	('a -> 'b -> 'd) -> 'a option -> 'b option -> 'd option
Option.toList	'a option -> 'a list

Path additions

Name	Signature
Path.normalize	string -> string
Path.isAbsolute	string -> bool
Path.combine	string -> string -> string
Path.fileName	string -> string
Path.extension	string -> string option
Path.fileNameWithoutExtension	string -> string
Path.parent	string -> string option
Path.relative	string -> string -> string option

Glob additions

Name	Signature
Glob.isMatch	string -> string -> bool
Glob.filter	string -> string list -> string list

SemVer additions

Name	Signature
SemVer.tryParse	string -> ({ Build: string; Major: string; Minor: string; Patch: string; PreRelease: string }) option
SemVer.format	{ Build: string; Major: string; Minor: string; Patch: string; PreRelease: string } -> string
SemVer.compare	string -> string -> int option

Encoding additions

Name	Signature
Encoding.utf8Encode	string -> int list option
Encoding.utf8Decode	int list -> string option
Encoding.base64Encode	int list -> string option
Encoding.base64Decode	string -> int list option
Encoding.hexEncode	int list -> string option
Encoding.hexDecode	string -> int list option
Encoding.uriEncode	string -> string option
Encoding.uriDecode	string -> string option

Hash additions

Name	Signature
Hash.sha256	string -> string option
Hash.sha256Bytes	int list -> string option