shift and reset in ice-9 control

[Andy Wingo]

Hello again Wolfgang,

On Wed 09 Mar 2011 11:53, Wolfgang J Moeller <address@hidden> writes:

> ;;; -*- scheme -*-
> ;;
> ;;; try reset & shift with GUILE V2 prompts
> ;;
> ;;
> (define-syntax reset
>   (syntax-rules ()
>     ((_ . body)
>      (call-with-prompt 'Reset
>                      (lambda () . body)
>                      (lambda (cont f) (f cont))))))
> ;;
> (define-syntax shift
>   (syntax-rules ()
>     ((_ var . body)
>      (abort-to-prompt 'Reset
>                     (lambda (cont)
>                       ((lambda (var) (reset . body))
>                        (lambda vals (reset (apply cont vals)))))))))
> ;;
> ;;
> (define (reset* thunk)
>   (reset (thunk)))
> ;;
> (define (shift* fc)
>   (shift c (fc c)))

Did you write these yourself?  May we include them in (ice-9 control)?

If you have additional useful tests, we are happy to include them as
well.  Probably the easiest thing would be to mail them to the list with
a permissive copyright header.

Cheers,

Andy
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