Hello.
For R7RS final draft, the syntax-rules for the case derived expression appears
to be incorrect. The order of the 4th <syntax rule> is incorrect.
The 4th <syntax rule> should be moved after the 5th <syntax rule> . If not,
the result1 pattern variable of the 4th <syntax rule> will incorrectly match
with an => in the input.
Best regards,
Joe N.
p.s. Here is a corrected version:
(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
(else result1 result2 ...))
(begin result1 result2 ...))
((case key
- ((atoms ...) result1 result2 ...))
- (if (memv key '(atoms ...))
- (begin result1 result2 ...)))
- ((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
+ ((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 ...)))))_______________________________________________
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