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 > > > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
