std/Pair.bruijn


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# MIT License, Copyright (c) 2022 Marvin Borner

:import std/Combinator .

# pairs two expressions into one
pair [[[0 2 1]]]

# extracts first expression from pair
fst [0 T]

# test fst with example pair of [[0]] and [[1]]
:test fst (pair [[0]] [[1]]) = [[0]]

# extracts second expression from pair
snd [0 F]

# test snd with example pair of [[0]] and [[1]]
:test snd (pair [[0]] [[1]]) = [[1]]

# applies both elements of a pair to a function
uncurry [[1 (fst 0) (snd 0)]]

# test uncurry with example pair of [[0]] and [[1]] and some combinator
:test uncurry W (pair [[0]] [[1]]) = [[1]]

# applies a function to the pair of two values
curry [[[2 (pair 1 0)]]]

# test curry with example pair of [[0]] and [[1]] and fst
:test curry fst [[0]] [[1]] = [[0]]

# swaps the values of a pair
swap [pair (snd 0) (fst 0)]

# test swap with example pair of [[0]] and [[1]]
:test swap (pair [[0]] [[1]]) = pair [[1]] [[0]]