; SRFI 87: => in case clauses
;
; $Id$
;
; Copyright (c) 2006 Chongkai Zhu. All Rights Reserved.
; 
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; a copy of this software and associated documentation files (the
; ``Software''), to deal in the Software without restriction, including
; without limitation the rights to use, copy, modify, merge, publish,
; distribute, sublicense, and/or sell copies of the Software, and to
; permit persons to whom the Software is furnished to do so, subject to
; the following conditions:
; 
; The above copyright notice and this permission notice shall be
; included in all copies or substantial portions of the Software.
; 
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; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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; WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

(define-syntax case
  (syntax-rules (else =>)
    ((case (key ...)
       clauses ...)
     (let ((atom-key (key ...)))
       (case atom-key clauses ...)))
    ((case key
       (else => result))
     (result key))
    ((case key
       ((atoms ...) => result))
     (if (memv key '(atoms ...))
         (result key)))
    ((case key
       ((atoms ...) => result)
       clause clauses ...)
     (if (memv key '(atoms ...))
         (result key)
         (case key clause clauses ...)))
    ((case key
       (else result1 result2 ...))
     (begin result1 result2 ...))
    ((case key
       ((atoms ...) result1 result2 ...))
     (if (memv key '(atoms ...))
         (begin result1 result2 ...)))
    ((case key
       ((atoms ...) result1 result2 ...)
       clause clauses ...)
     (if (memv key '(atoms ...))
         (begin result1 result2 ...)
         (case key clause clauses ...)))))

; eof
