Callable arrows

Musi uses arrows when code describes or builds callable values.

Callable type arrow ->

Use -> in a type when a value is callable.

let mapper : Int -> Int := \(value : Int) : Int => value + 1;

Read Int -> Int as "takes an Int and returns an Int."

Effect arrow ~>

Use ~> for callable shapes that can perform effects.

let Pure := Int -> Int;
let Effectful := Int ~> Int;
Pure;

Read Int ~> Int as "takes an Int, may perform an effect, and returns an Int."

Lambda body arrow =>

Use => between a lambda header and its body.

let addOne := \(value : Int) : Int => value + 1;

The left side names parameters and the result type. The right side is the expression that produces the result.

Pick the right arrow