fun/rng-state.bruijn

# MIT License, Copyright (c) 2024 Marvin Borner
# generates three pseudo-random integers using a state monad
# printf <seed:number> | bruijn rng-state.bruijn

:import std/Combinator .
:import std/String .
:import std/Number .
:import std/Monad/State .

max (+1000)

rand [[[0 1 1]] rng]
	rng (+1103515245) ⋅ 0 + (+12345) % max

rand-bool map even? rand

# accumulating bind (reversed)
triple1 rand >>= (rand >>= (rand >>= [[[[[0 3 [0 3 [0 3 [[0]]]]]]]]]))

:test ((triple1 (+50) [[1]]) =? (+745)) ([[1]])

# normal bind
triple2 rand >>= [rand >>= [rand >>= [[[0 4 [0 4 [0 4 [[0]]]]]]]]]

:test ((triple2 (+50) [[1]]) =? (+595)) ([[1]])

main string→number → triple2