I can do it.

-Philip


On Thu, Nov 29, 2018 at 5:17 PM John Clements <cleme...@brinckerhoff.org>
wrote:

> I like your idea better than mine. Do you have time to make it a pull
> request? If not, I’ll do it.
>
> John
>
> > On Nov 29, 2018, at 2:08 PM, Philip McGrath <phi...@philipmcgrath.com>
> wrote:
> >
> > I would find `true?` confusing, since it really means "truthy." For
> example, in Rackunit, `check-not-false` has this behavior, whereas
> `check-true` checks that the result is really `eq?` to `#t`.
> >
> > Personally, I think it might be better to clarify the documentation with
> more prose, rather than adding a new binding to the standard library. Maybe
> something like this?
> > Like (map proc lst ...), except that, when `proc` returns `#f`, that
> element is omitted from the resulting list. In other words, filter-map is
> equivalent to (filter (lambda (x) x) (map proc lst ...)), but more
> efficient, because filter-map avoids building the intermediate list.
> >
> > -Philip
> >
> >
> > On Thu, Nov 29, 2018 at 3:25 PM Gustavo Massaccesi <gust...@oma.org.ar>
> wrote:
> > This function is a already defined in a few libraries and it is called
> `true?` for example in
> https://docs.racket-lang.org/predicates/index.html?q=true#%28def._%28%28lib._predicates%2Fmain..rkt%29._true~3f%29%29
> >
> > I think that `not-false?` is easier to understand, but `true?` is more
> idiomatic.
> >
> > Gustavo
> >
> >
> >
> >
> > On Thu, Nov 29, 2018 at 3:11 PM 'John Clements' via Racket Users <
> racket-users@googlegroups.com> wrote:
> > This stack overflow post
> >
> >
> https://stackoverflow.com/questions/53543191/what-is-the-different-between-filter-and-filter-map/53545115#53545115
> >
> > … is written by someone confused by the documentation for `filter-map`.
> I went and read the documentation, and *I* was confused for about 30
> seconds. I eventually proposed rewriting the existing
> >
> > Returns (filter (lambda (x) x) (map proc lst ...)), but without building
> the intermediate list.
> >
> > to
> >
> > Returns (filter not-false? (map proc lst ...)), but without building the
> intermediate list, where not-false? can be defined as (lambda (x) x).
> >
> > This text is kludgier, but I think that the use of (lambda (x) x) as
> “not-false?” is idiomatic and confusing. And yes, I realize that this
> suggestion probably applies to many places in the docs. Maybe I should just
> propose adding `not-false?` as a library function, defined as (lambda (x)
> x)….
> >
> >
> > John
> >
> >
> >
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