On Mon, Jun 10, 2013 at 1:20 PM, Steven Degutis <sbdegu...@gmail.com> wrote:
> Sometimes I've wanted a function that takes a value and a bunch of tests, > and returns it if it passes every test, otherwise nil. > > So I wrote if-and: > > (if-and "foo" > > string? > #(.startsWith % "f") > #(.contains % "oo")) > ;; => "foo" > > (if-and "foo" > string? > #(.startsWith % "f") > #(.contains % "NOT IN THE STRING")) > ;; => nil > > > Source: > https://github.com/evanescence/if-and/blob/master/src/if_and/core.clj > > Does this seem useful enough to put into core? > > "Takes a value and a bunch of tests, and returns [the value] if it passes every test" implies that (if-and false false?) should return false, but: user> (if-and false false?) nil It's also kind of confusing to me *anyway* that (if-and false false?) would return false and not true (to indicate that the supplied value passed every test). Something like this seems more intuitive to me: user> (defn allpreds [x & ts] (every? #(% x) ts)) #'user/allpreds user> (allpreds false false?) true user> (allpreds nil false?) false With if-and being definable in terms of allpreds: user> (defn if-and* [x & ts] (when (apply allpreds x ts) x)) #'user/if-and* user> (if-and* false false?) false user> (if-and* false nil?) nil -- Ben Wolfson "Human kind has used its intelligence to vary the flavour of drinks, which may be sweet, aromatic, fermented or spirit-based. ... Family and social life also offer numerous other occasions to consume drinks for pleasure." [Larousse, "Drink" entry] -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
