# MIT License, Copyright (c) 2022 Marvin Borner

:import std/Combinator .

# empty option
none T

# encapsulates value in option
some [[[0 2]]]

# checks whether option is none
none? [0 T [F]]
:test none? none = T
:test none? (some [[0]]) = F

# checks whether option is some
some? [0 F [T]]
:test some? none = F
:test some? (some [[0]]) = T

# applies a function to the value in option
map [[0 none [some (2 0)]]]
:test map [[1]] (some [[0]]) = some [[[0]]]
:test map [[1]] none = none

# applies a function to the value in option or returns first arg if none
map-or [[[0 2 1]]]
:test map-or [[[2]]] [[1]] (some [[0]]) = [[[0]]]
:test map-or [[[2]]] [[1]] none = [[[2]]]

# extracts value from option or returns first argument if none
unwrap-or [[0 1 I]]
:test unwrap-or F (some T) = T
:test unwrap-or F none = F

# applies encapsulated value to given function
apply [[1 none 0]]
:test apply none [some ([[1]] 0)] = none
:test apply (some [[0]]) [some ([[1]] 0)] = some [[[0]]]