> On Apr 22, 2018, at 1:40 PM, Zelphir Kaltstahl <zelphirkaltst...@gmail.com>
> wrote:
>
> Ah OK, I understand that additional newline. Since the code matching the
> regex is run before that newline gets in, the newline will be on the
> input port.
>
> In DrRacket I observe the following:
>
> (I remembered that there are negative numbers :D and my regex got a bit
> more complicated.)
Parsing numbers with regex is prone to error, because you'll often miss edge
cases. For instance, did you remember that -0/42 is an exact integer?
A nice way to avoid these headaches is to delegate the heavy lifting to `read`,
and then just test the result value:
#lang racket
(for/first ([val (in-port read)]
#:when (exact-integer? val))
val)
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