# MIT License, Copyright (c) 2023 Marvin Borner
# monadic interface for anything based on lists (e.g. IO, strings)
# afaik originally proposed by John Tromp and inspired by Haskell

:import std/Pair .
:import std/Combinator .

read [0] ⧗ a → (M a)

return [[1 : 0]] ⧗ a → (M a)

pure return ⧗ a → (M a)

# monadic bind operator
…>>=… [[[2 0 1]]] ⧗ (M a) → (a → (M b)) → (M a)

:test ((read >>= return) "woa") ("woa")

# monadic reverse bind operator
…=<<… \…>>=… ⧗ (a → (M b)) → (M a) → (M b)

:test ((return =<< read) "woa") ("woa")

# monadic compose operator
…>>… [[1 >>= [1]]] ⧗ (M a) → (M b) → (M b)

:test ((read >> (return 'a')) "hah") ("aah")