Klisp

A Toy 🧸 Lisp interpreter written in Kotlin

Inspiration

• (How to Write a (Lisp) Interpreter (in Python))
• SICP

Supported Features

Syntax

• definition (define symbol exp)
• lambda definition (lambda (symbol...) exp)
• procedure call (proc arg...)
• conditional (if test conseq alt)
• function definition shorthand (define (symbol param...) exp)
• block structure

Types

• int
• float

Test Programs

klisp can currently run programs from SICP like this.

(define (sqrt x)
  (define (abs x)
    (if (< x 0) (* -1 x) x))
  (define (average x y)
    (/ (+ x y) 2))
  (define (square x)
    (* x x))
  (define (good-enough? guess)
    (< (abs (- (square guess) x)) 0.001))
  (define (improve guess)
    (average guess (/ x guess)))
  (define (sqrt-iter guess)
    (if (good-enough? guess)
        guess
        (sqrt-iter (improve guess))))
  (sqrt-iter 1.0))
  
(sqrt 25)

See https://github.com/yujinyan/klisp/blob/master/src/test/kotlin/SicpPrograms.kt for more test programs.