Callum's Lisp

A Lisp interpreter designed to be run in the browser using WASM.

Usage

You can perform simple numerical operations using +, -, *, and /:

(+ 1 2) => 3
(/ 5 2) => 2.5
(- 2) => -2
(/ 5) => 0.2

You can define constants using def:

(def x 3) => 3
x => 3

You can create functions using lambda:

(lambda (x) (+ x 1)) => <function>
(def add1 (lambda (x) (+ x 1))) => <unspecified>
(add1 3) => 4

List of all builtin functions and special forms

Special forms

• (def name value): creates a binding of name to value in current environment
• (lambda (bindings) expr) or (λ (bindings) expr): creates a function
• (if cond do else): evaluate do expr if cond is true, otherwise evaluate else expr

Builtin functions

• +,-,*,/: simple arithmetic operators
• exit: exits with code 0 or code provided by argument
• eval: evaluate the expression passed as an argument
• use: evaluate all expressions contained in a file in the current environment
• putstr: print a string to stdout
• readline: read a line from stdin
• equal?: check if any amount of values are equal
• >, >=, <, <=: number comparison operators
• list: creates a list out of arguments given
• list?: returns true if argument is a list, otherwise returns false
• empty?: returns true if argument is a list of length 0, otherwise returns false
• count: returns the length of the argument if the argument is a list

Goals

Goals in order of priority:

• Tail call optimization
• Macros
• Proper error handling
• Strings
• Multi-precision numbers
• Vectors
• Structs/enums/union types
• IO (print, readline, etc.)