Thread: Help getting Ideas on Challenging Programes to write

Writing a simple interpreter can be a lot of fun.
Start with a calculator that does arithmetic.

Code:

(+ 2 3)

Add variables

Code:

(let (a 5) (+ a 5))

Conditions

Code:

(if (x > 5) (+ x 1) (- x 1) )

Functions

Code:

(define  foo (n) (+ n 1))
(foo 5)

Recursion?

Code:

(define  sum (n) (if (= n 0) (0) (+ n (sum (- n 1)))))

Congratulations, you have your own Turing complete programming language!

(Also, you are one simple trick away from LISP.)