On 7/17/2020 8:19 PM, Hendrik Boom wrote:
Yes, I know the functino for reading s-expressions seems to be (read [in]).
I want a loop that reads S-expressions and does something to each one, until
there are no more to be found in a file.
Now of course that's absurdly easy to do with a tail-recursice loop.
But I's like it to look like a loop, with (for ...) or (while ...) or
(loop ...) or something like that.
But I fail to fine any iterators that process a file, such as (in-file
...)
There's a long list of iterators in
https://docs.racket-lang.org/reference/for.html
and in
https://docs.racket-lang.org/guide/for.html
An I just looking in the wrong place, or are there really no iterators
for reading a stream of s-expressions from a file.
-- hendrik
This should work if you're reading the sexprs for value:
(with-input-from-file /filename/
(lambda ()
(for [(expr (read))]
:
)))
If your intent is to read/parse the sexprs as text, there isn't a simple
way to do that. Regex is problematic for nested expressions ... you
could try "read-syntax" if you are familiar with macros, or "match" if
you know what patterns to look for.
There's no "in-match" sequence, so if you want a loop that *appears*
simple [match in the /"for-clause"/], you'll have to write some glue: a
helper that returns one match result at a time so as to plug nicely into
a loop.
George
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