let prelude = import! std.prelude
let { (<|) } = import! std.function
let { Test, run, assert, assert_eq, test, group, ? } = import! std.test
let int = import! std.int
let state @ { State, put, get, modify, runState, evalState, execState, ? } = import! std.state
let { Applicative, wrap, (*>), ? } = import! std.applicative

group "state" [
    test "modify execState" <| \_ -> (assert_eq (execState (modify (\x -> x + 2) *> modify (\x -> x * 4)) 0) 8),
    test "modify evalState" <| \_ -> (assert_eq (evalState (modify (\x -> x + 2) *> get) 0) 2),
    test "put get evalState" <| \_ -> (assert_eq (evalState (put "hello" *> get) "") "hello"),
    test "put get runState" <| \_ -> (assert_eq (runState (put "hello" *> get) "").value "hello"),

    /* FIXME
    test "record unpack runState" <| \_ ->
        let m : State { x : Int } Int =
            do { x } = get
            wrap x
        assert_eq (evalState m { x = 1 }) 1,
    */
]