[r6rs-discuss] [Formal] SRFI-39 should be made an R6RS library

[Abdulaziz Ghuloum]

On Feb 20, 2007, at 11:05 PM, John Cowan wrote:

> Apparently, Chicken requires
> parameter procedures to return only one value.

So does Chez.  In the following, using the procedure "values" as a guard
is a shorthand for (lambda (x) x) since returning multiple values to a
single-value context raises an error in Chez.

   (define make-parameter
     (case-lambda
       [(init guard)
        (let ([v (guard init)])
          (case-lambda
            [() v]
            [(u) (set! v (guard u))]))]
       [(init) (make-parameter init values)]))

Aziz,,,
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