Function litto::lang::minilang::stdlib::define

pub fn define(
    env: &<MiniLang as Interpreter>::Env, 
    args: &[<MiniLang as Interpreter>::Expr]
) -> Result<<MiniLang as Interpreter>::Value, <MiniLang as Interpreter>::Error>

(define name value)

(define (f x) value) is a syntactic sugar of (define f (lambda (x) value)).