Getting started

$ nix run git+https://git.avery.garden/thorn/narju

naj with no argument is the prompt, naj FILE runs a file and exits. the other forms are naj --lock, which resolves naj.deps into naj.lock (see Modules), and --modules DIR, which says where fetched modules live.

narju> (+ 1 2)
3

narju> (define (double n) (* n 2))
'double

narju> (map double '(1 2 3))
(2 4 6)

the prompt is naj/repl.naj, an object program running as a task with its environment as task state. hence a definition surviving to the next line, and a throw not killing the session.

Surface

lambda, let, if, quote, cond, case, and, or, begin, define, quasiquote. lambda takes an optional self name before the parameter list, so recursion needs no letrec:

narju> ((lambda loop (n) (if (eq? n 0) 'done (loop (- n 1)))) 3)
'done

falsity is 0 and '(). everything else is true, including "". predicates answer 1 or 0.

narju> (if 0 'a 'b)
'b

narju> (if '() 'a 'b)
'b

let destructures, and a pattern that does not match throws:

narju> (let (((a b . rest) '(1 2 3 4))) (list a b rest))
(1 2 (3 4))

there is no print. say sends a line to the stdout capability:

narju> (say (list 1 "two" 'three))
(1 "two" 'three)
'ok

the 'ok is the value of say itself, which the prompt shows like any other.

A file

; hello.naj
(define (fib n)
  (if (< n 2) n (+ (fib (- n 1)) (fib (- n 2)))))

(say (fib 20))

$ naj hello.naj
6765

a file’s definitions nest into the body that follows them, so a file is one expression and there is no top level.

a world stays alive while any task can still run, so a script that spawns a server and never stops it does not exit. see Tasks and messages.