leviathan

Types

State monad

pub type State(s, a) {
  State(run: fn(s) -> #(a, s))
}

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pub fn do(
  st: State(a, b),
  f: fn(b) -> State(a, c),
) -> State(a, c)

Monadic bind (>>=) that allows you to use gleam’s use syntax as a replacement for do notation

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pub fn eval(st: State(a, b), initial: a) -> b

Apply a state function st to an initial state and just return the computation’s result

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pub fn exec(st: State(a, b), with initial: a) -> a

Apply a state function st to an initial state and return the final state

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pub fn get() -> State(a, a)

Sets the resulting value to the current state

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pub fn go(st: State(a, b), initial: a) -> #(b, a)

Apply a state function st to an initial state and return a pair of a value and the final state

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pub fn map(st: State(a, b), f: fn(b) -> c) -> State(a, c)

Apply the function f to the resulting value of s

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pub fn modify(f: fn(a) -> a) -> State(a, Nil)

Apply the function f to the current state Replaces the return value with Nil

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pub fn put(x: a) -> State(a, Nil)

Sets the state value to a given state x Replaces the return value with Nil

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pub fn return(x: a) -> State(b, a)

Monadic return that allows you to use gleam’s use syntax as a replacement for do notation Check do for examples