X-lisp

X-lisp is a simple lisp interpreter. So far, everything is a function.

This is general construct of the language (name args args), the first argument inside parenthesis is the function name, and the subsequent is the function arguments.

Installation

Make sure you have Deno installed, if not you can install it here.

$ deno install --allow-read github.com/issadarkthing/x-lisp/xlisp.ts

Data types (Kind)

Two major data type in x-lisp is Fn and Kind. Fn is function type which takes at least one argument; the symbol. Everything with the parenthesis is a Fn type. In fact, the whole module is a big prog function (we will talk about this later). Every Fn creates a new scope, the variables defined inside Fn is only visible within Fn.

Primitive data types are Kinds. They are not callable and cannot be the first item inside a parenthesis.

• string
• number
• nil
• boolean
• cons list

Cons

Cons is a list and the only data structure so far in the language. The cons function is a variadic function which means it takes multiple arguments and returns a cons.

Math

function	description
(+ a b)	add numbers
(- a b)	subtract numbers
(* a b)	multiply numbers
(/ a b)	divide numbers

Logical function

function	description
(and a b)	and &&
(or a b)	or ||
(eq a b)	equal ==
(ne a b)	not equal !=
(gt a b)	greater then >
(ge a b)	greater then or equal >=
(lt a b)	lesser then <
(le a b)	lesser then or equal <=

Function

defun is a function that takes 3 arguments: identifier, cons, function.

(defun adder (# a b c)
	(+ a b c))

Variable binding

set bind a Kind to a symbol. The symbol is visible inside the parent scope.

(set a 10 b 12)

Control flow (expression)

if is not a statement but rather a function which takes 3 Fn types. The first argument must be an Fn that returns a bool Kind.

(if (< 10 11)
	(id "so truee")
	(id "so wrong"))

Notice the id function, it is needed there because it needs to turn Kind type to Fn type.