case-lambda -- r7rs Definition
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syntax;

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Description
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(case-lambda <clause> ...)

Syntax: Each <clause> is of the form (<formals> <body>), where <formals> and <body> have the same syntax as in a lambda expression.

Semantics: A case-lambda expression evaluates to a procedure that accepts a variable number of arguments and is lexically scoped in the same manner as a procedure resulting from a lambda expression. When the procedure is called, the first <clause> for which the arguments agree with <formals> is selected, where agreement is specified as for the <formals> of a lambda expression. The variables of <formals> are bound to fresh locations, the values of the arguments are stored in those locations, the <body> is evaluated in the extended environment, and the results of <body> are returned as the results of the procedure call.

It is an error for the arguments not to agree with the <formals> of any <clause>.

(define range
  (case-lambda
   ((e) (range 0 e))
   ((b e) (do ((r '() (cons e r))
               (e (- e 1) (- e 1)))
              ((< e b) r)))))

(range 3)    ===> (0 1 2)
(range 3 5)  ===> (3 4)

The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.

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