Functions and types

defun names a function. Parameters may have name: Type annotations and -> introduces a return type. defstruct defines named fields; defenum defines alternatives that match handles. This example sums the fields of a point. Option and Result are enums used throughout the library. Next: ownership.

(ns main)
(defstruct Point (x: i64 y: i64))
(defenum Shape (At point: Point) (Empty))
(defun describe (s: Shape) -> i64
  (match s ((At p) (+ (. p x) (. p y))) ((Empty) 0)))
(defun main () -> i64 (do (println (describe (At (Point 3 4)))) 0))

7
0