guile-borrow is a Guile library that borrows syntax and features from other Lisps, namely Racket and Clojure. The main purpose of this collection is to make Guile more familiar to other lisp programmers, as a primarily extension language, ubiquity must be its main power – it has to be widely used, and it has to be familiar to many people.

On the one hand it is a collection of features which are typically implemented using Macros and on the other hand it is a library that facilitates adding more constructs – which primarily means introducing more sophisticated macros systems from other Lisp dialects.

Not all language features can be simply added to the the language in forms of syntax macros. For that reason more complicated borrowed features will be implemented in forms of *Guile* extensions.

Examples

;; A clojure-like let
(define-syntax let1
  (syntax-rules ()
    ((_ (var val) exp exp* ...)
     (let ((var val)) exp exp* ...))))

;; If test is true, evaluates then with binding-form bound to the
;; value of test, if not, yields else
(define-syntax if-let
  (syntax-rules ()
    ((_ (binding value) then else)
     (let1 (binding value)
           (if binding then else)))))

;; When test is true evaluates body with binding-form bound to the
;; value of test
(define-syntax when-let
  (syntax-rules ()
    ((_ (binding value) body ...)
     (let1 (binding value)
           (when binding body ...)))))

;; a short-hand to (if (not something) ...)
(define-syntax if-not
  (syntax-rules ()
    ((_ test then else)
     (if (not test) then else))))

;; Like when but reversed
(define-syntax when-not
  (syntax-rules ()
    ((_ test body ...)
     (when (not test) body ...))))