A simple lisp-like interpreter written in c

WARNING: Work in progress

This is a simple interpreter with a repl.

Currently it only supports:

• basic arithmetic operators (+ - / *)
• basic relational operators (> < = /=)
• basic control flow (if switch while)
• lexical scoping (let)
• anonymous functions (lambda)
• named functions (def)
• assignment (:=)

Todo

• Add error handling
• Read from file
• while statements
• lexical scoping
• lambdas
• Named functions

Starting program

Ensure that you have make installed.

To build and start the repl, run this in the command line:

make run

Example session

Starting REPL:
Use exit() to exit the program
>> 1
1
>> 2
2
>> (+ 1 2)
3
>> ( / 8 2 )
4
>> (/ 8 2 2 2)
1
>> (* 20 100)
2000
>> (if 1 1 2)
1
>> (if 0 1 2)
2
>> (if (- 2 1) 1 2)
1
>> (switch 3 (case 1 2) (case 3 4))
4
>> (switch 1 (case 1 2) (case 3 4))
2
>> (:= x 4)
4
>> x
4
>> (> 2 1)
1
>> (= 1 2 1 1 2)
0
>> (< 1 2 3 4 5)
1
>> (:= a 5)
5
>> (:= b 2)
2
>> (while a (:= a (- a 1)) (:= b (+ b 1) ))
7
>> b
7
>> (let ((x 2)) x)
2
>> (:= x 4) (let ((x 2)  (y 3))) x
4
0
4
>> (let ((x 2) (y 3)) (:= y (+  1 x)) (:= x (+ 1 y)) x)
4
>> ((lambda (x y) (+ x y)) 1 2)
3
>> (:= x 2) ((lambda (y) (+ x y)) 3)
2
5
>> (def plusOne (x) (+ x 1))
plusOne
>> (plusOne 5)
6
>> (def multiBody (x y ) (:= x (+ x y))   (:= y (+ y x)))
multiBody
>> (multiBody (plusOne 2) 6)
15
>> exit()