Std\Pair

ADT-based pairs with named fields — an alternative to tuples.

Unlike tuples, Pair is a proper ADT with named fields (fst, snd), enabling dot access and named pattern matching.

Types

Pair

type Pair a b = Pair { fst : a, snd : b }

A pair with named fields.

Functions

pair : a -> b -> Pair c d

Creates a pair from two values.

pair 1 2   # => Pair { fst = 1, snd = 2 }

first : Pair a b -> c

Extracts the first element.

first (pair 1 2)   # => 1

second : Pair a b -> c

Extracts the second element.

second (pair 1 2)   # => 2

mapFirst : (a -> b) -> Pair c d -> Pair e f

Transforms the first element.

mapFirst (\x -> x * 10) (pair 3 5)   # => Pair { fst = 30, snd = 5 }

mapSecond : (a -> b) -> Pair c d -> Pair e f

Transforms the second element.

mapSecond (\x -> x * 10) (pair 3 5)   # => Pair { fst = 3, snd = 50 }

mapPair : (a -> b) -> (c -> d) -> Pair e f -> Pair g h

Transforms both elements with two functions.

mapPair (\x -> x + 1) (\x -> x * 2) (pair 3 5)   # => Pair { fst = 4, snd = 10 }

swap : Pair a b -> Pair c d

Swaps the two elements.

swap (pair 1 2)   # => Pair { fst = 2, snd = 1 }

toTuple : Pair a b -> (c, d)

Converts to a tuple (a, b).

toTuple (pair 1 2)   # => (1, 2)

fromTuple : (a, b) -> Pair c d

Creates a pair from a tuple.

fromTuple (1, 2)   # => Pair { fst = 1, snd = 2 }