Lisp interpreter written in C

• Clone: git clone https://github.com/mmniazi/lisp.git
• Build (required for run or repl): make
• Run: lisp my_file.lisp
• Repl: lisp

• Primitive data types and strings
• Common operators (+, -, *, /, >, <=, == ...)
• Comments
• Variables
• Flow control (if/else, while, switch)
• Functions & lambdas
• Higher order functions
• Scopes
• S-expressions
• Q-expressions/lists and list operators
• Varargs
• Importing code
• Error reporting and stack traces

; Fibonacci (fun {fib n} { select { (== n 0) 0 } { (== n 1) 1 } { otherwise (+ (fib (- n 1)) (fib (- n 2))) } }) 

Call function with given list of args

= {params} {1 2 3} fun {plus x y z} {+ x y z} (curry plus params) > 6 

Call function with single list created from args

uncurry print 1 2 3 > {1 2 3} 

Perform no of actions in sequence

do (= {x} 2) (+ x 4) > 6 

Create a local scope

let {do (= {x} 100) (x)} > 100 x > Error: Unbound Symbol 'x' 

Logical functions

or (and true false) true > 1 

Flip arguments for currying

flip / 1 2 > 2 

apply functions in sequence (comp f g x) -> f(g(x))

comp head last {1 2 {3 4 5}} 

Return first, second or third element of list

fst {1 2 3 4} > 1 snd {1 2 3 4} > 2 trd {1 2 3 4} > 3 

Return element on nth index

nth 2 {1 2 3 4} > 3 

Return last element of list

last {1 2 3} > 3 

Length of list

len {1 2 3 5} > 4 

Take N items from list

take 2 {1 2 3 5} > {1 2} 

Drop N items from list

drop 2 {1 2 3 5} > {3 5} 

Split list at Nth element

split 1 {1 2 3 5} > {{1 2} {3 5}} 

Check for presence of element

elem 5 {1 2 3 5} > 1 elem 9 {1 2 3 5} > 0 

Create new list by applying function to every elem of list

fun {square x} {* x x} map square {1 2 3} > {1 4 9} 

Create a new list of items which match the condition

fun {even x} {== (% x 2) 0} filter even {1 2 3 4} > {2 4} 

Fold left

foldl * 1 {2 2} > 4 

switch statement, takes zero or more (cond, body) pairs

(fun {numbers x} { case x {0 "Zero"} {1 "One"} }) numbers 0 > Zero 

• Most of this repo is direct implementation of this amazing book with major difference being that I have written my own tokenizer and parser, instead of using parser-combinator library.