pretty-literals.lisp

;;;; pretty-literals.lisp - pretty hash table & vector literal syntax
;;;; inspired by and uses code from http://frank.kank.net/essays/hash.html

(in-package #:pretty-literals)

;; vector literal syntax using brackets
(set-macro-character #\[
		     (lambda (str char)
		       (declare (ignore char))
		       (let ((*readtable* (copy-readtable *readtable* nil))
			     (keep-going t))
			 (set-macro-character #\] (lambda (stream char)
						    (declare (ignore char) (ignore stream))
						    (setf keep-going nil)))
			 (let ((items (loop for value = (read str nil nil t)
					while keep-going
					collect value)))
			   (coerce items 'vector)))))

;; hash-table literal syntax using braces
(set-macro-character #\{
		     (lambda (str char)
		       (declare (ignore char))
		       (let ((*readtable* (copy-readtable *readtable* nil))
			     (keep-going t))
			 (set-macro-character #\} (lambda (stream char)
						    (declare (ignore char) (ignore stream))
						    (setf keep-going nil)))
			 (let ((pairs (loop for key = (read str nil nil t)
					   while keep-going
					   for value = (read str nil nil t)
					   collect (list key value)))
			       (retn (gensym)))
			   `(let ((,retn (make-hash-table :test #'equal)))
			      ,@(mapcar
				 (lambda (pair)
				   `(setf (gethash ,(car pair) ,retn) ,(cadr pair)))
				 pairs)
			      ,retn)))))