At Sun, 22 Apr 2018 14:54:26 +0200, Zelphir Kaltstahl wrote:
> I am sorry, I think I am still misunderstanding it.
> When I try:
> (regexp-try-match #rx"^[1-9]+[0-9]*$" (current-input-port))
> It also results immediately in:
>  #f

Using stdin both for reading an expresion and getting input can be
confusing. At Racket's ">" prompt, when you run

 >  (regexp-try-match #rx"^[1-9]+[0-9]*$" (current-input-port))

by hitting Return, then a newline is included is in the input stream
just after the `(regexp-try-match ...)` expression. That newline is
still there when you try to match against the regexp, so the match

DrRacket separates the input stream for expressions and for
`current-input-port`. So, if you try that expression in DrRacket's
interactions area, and if you hit the "EOF" button (to the right of the
input box) instead of Return after a number, then you should get a
match. Note that if you hit Return after the number, then it won't
match even in DrRacket, because the input port will have a newline
after the number.

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