Pyrens

Pyrens is an experimental Lisp compiler for Python. A basic Lisp syntax and Python interoperability are currently supported, as documented below. Please see the examples folder for more detailed code samples.

Built-In

; A few basic operations
(> & args)
(< & args)
(+ & args)
(- & args)
(* & args)
(/ & args)
(= & args)

; Branching
(if expression then & else)

; A generic printing facility
(print "Hello World!")

Definitions

(def myvalue 17)

Lists

Lists are represented internally by Python tuples.

(def mylist (list 1 2 3 4 5))

(print "List: " mylist)  ; (1, 2, 3, 4, 5)
(nth mylist 0)   ; 1
(nth mylist 5)   ; None
(first mylist)   ; 1
(last mylist)    ; 5
(count mylist)   ; 5
(rest mylist)    ; (2, 3, 4, 5)
(pop mylist)     ; (2, 3, 4, 5) - as a new list
(cons 0 mylist)  ; (0, 1, 2, 3, 4, 5) - as a new list

(def plus5
  (fn (i)
    (+ i 5)))

(print (map plus5 mylist)) ; (6, 7, 8, 9, 10) - as a new list

Hash Maps

Hash Maps are backed by Python dictionaries. However, they are not mutable. To modify a hash, use merge to create a new hash containing elements from both.

(def myhash1 (hash-map "key1" 1 "key2" (list 1 2 3)))
(def myhash2 (hash-map "key3" 3))

(get myhash1 "key1")            ; 1
(nth (get myhash1 "key2") 1)    ; 2
(count (merge myhash1 myhash2)) ; 3

Functions

(def add3
  (fn (a b c)
    (+ a b c)))

(print (add3 1 2 3))

Let Expressions

(def add2plus7
  (fn (a b)
    (let ((c 5)
          (d 2))
      (+ a b c d))))

(print (add2plus7 1 2))

Python Interop

Python interop may be removed entirely in the future. Right now it exists largely as a side-effect of the forgiving writer.

(import requests)

(def fetch
  (fn (url)
    (requests.get url)))

(print (fetch "http://www.google.com/"))

Usage

The run.py script in the root folder will generate .py files for every .lisp file in the examples folder. If you would like to play with Pyrens, I suggest simply adding examples of your own. I hope to eventually provide a stand-alone script to execute .lisp files directly.

Contact

Please contact me at [email protected] or file an issue with any suggestions you might have!