2016-04-04 21:34 GMT+02:00 rom cgb <romainbeck...@gmail.com>:
> Hi,
>
> Trying to use eof in a case expression but it doesn't work.
>
> For example
>
> (define (test x)
> (case x
> [(eof) eof]
> [else "else"]))
>
>
> (test eof) will then evaluate to "else" despite (equal? eof eof)
> evaluating to #t.
>
> Why ?
The (eof) clause in case is a list of datums. That means case
will taste for the symbol eof and not the end of file object.
(case 'eof
[(eof) 42]) ; 42
(case eof
[(eof) 42]
[else #f]) ; #f
Instead use cond
(cond
[(eof-object? x) ...]
[else #f])
/Jens Axel
>
>
>
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--
--
Jens Axel Søgaard
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