src/code/cmacros.lisp

   1 ;;;; Compiler macros that are important for the target system
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!IMPL")
  13
  14 ;;;; We often use a source-transform to do macro-like rewriting of an
  15 ;;;; ordinary function call. Source-transforms seem to pre-date the ANSI
  16 ;;;; specification and are redundant with compiler-macros.
  17 ;;;; In the interest of not multiplying entities needlessly, it should
  18 ;;;; be feasible to get rid of source-transforms.
  19 ;;;; A problem is namespace clobbering: these must not affect the host Lisp.
  20
  21 (define-compiler-macro append (&whole form &rest lists)
  22   (case (length lists)
  23     (0 nil)
  24     (1 (car lists))
  25     (2 `(append2 ,@lists))
  26     (t form)))
  27
  28 ;;; A sanity-checker for an extremely common programmer error.
  29 (define-compiler-macro format (&whole form destination control &rest args)
  30   (declare (ignore control args))
  31   (when (stringp destination)
  32     (warn "Literal string as destination in FORMAT:~%  ~S" form))
  33   form)