API - Tuples

JavaScript implementation of tuples, with support for flattening and pattern-matching. This implementation does not support unit or singleton tuples. Additionally, pair tuples are specialized to support the fst and snd pair operations.

Tuples constructors

Tuple(x, y [, ...])

Creates a tuple, or a pair as appropriate.

Throws TypeError if attempting to create unit (zero argument) or singleton (one argument) tuples.

Pair(x, y)

Creates a pair (which is a specialized instance of tuple).

Throws TypeError if too few or too many arguments are provided.

Tuple.fromArray(array)

Converts an array to a tuple as appropriate.

This factory method will return one of the following depending on the length of array:

0: undefined
1: array[0]
2: Pair(array[0], array[1])
3: Tuple(array...)

Tuple properties and methods

tuple.length: The number of component in the tuple.
tuple.item(n): Returns the n-th component in the tuple.
tuple.bind(f): Calls the function f with tuple as the argument.
tuple.applyTo(f): Calls the function f with the components of tuple as the arguments.

Pair methods

pair.fst(): Returns the first component in the pair.
pair.snd(): Returns the second component in the pair.

Tuple flattening

tuple.Array(): Flattens tuple, including nested tuples, into an array.
tuple.applyArrayTo(f): Calls the function f with tuple.Array() as the arguments.

Tuple pattern-matching

tuple.match(pattern)

Matches a tuple to a pattern and returns an object with properties containing the matched values.

pattern is a string written in the following grammar:

tuple-pattern ::= tuple-component (',' tuple-component)+
tuple-component ::= identifier | blank | '(' tuple-pattern ')'

Throws:

TypeError if the pattern is invalid.
MatchError if the tuple does not match the pattern.

Example:

Tuple(1,2,Tuple(Tuple(3,4),5)).match("a,,(b,c)") returns
{ a:1; b:Tuple(3,4); c:5 }

match can be used with the JavaScript with keyword to bring the matched values into scope: