-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 what about
>> (cond (= dir :left) ((move-left)(:ok)) (= dir :up) >> ((move-up)(:ok)) :else :nok) or whatever the exact syntax is Am 05.11.2011 08:22, schrieb Alan Malloy: > On Nov 4, 11:49 pm, Baishampayan Ghose <b.gh...@gmail.com> wrote: >> On Sat, Nov 5, 2011 at 11:55 AM, Martin DeMello >> <martindeme...@gmail.com> wrote: >>> What's the cleanest way to run a piece of code if any branch of >>> a cond statement succeeded, without relying on the return value >>> of the individual clauses not to be nil? >> >>> For example, if I have the following piece of code that says I >>> can only move left or up >> >>> (cond (= dir :left) (move-left) (= dir :up) (move-up)) >> >>> but (move-left) or (move-up) could themselves return nil, is >>> there any nice way to check if one of them was called? >> >> What about something like this - >> >> (cond (= dir :left) (move-left) (= dir :up) (move-up) :else >> :nok) >> >> Or >> >> (cond (= dir :left) [(move-left)] (= dir :up) [(move-up)]) > > Seconded. Though if you can't easily predict what > move-left/move-up might return (ie they might even return :nok) you > might need to be more careful. Use a namespaced keyword like > :my-current-ns/didnt-do- anything, or a gensym (or a fresh Object) > for guaranteed uniqueness: > > (let [nothing (Object.) cond-result (case dir :left (move-left) :up > (move-up) nothing)] (if (identical? nothing cond-result) ...)) > - -- -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBAgAGBQJOtP9TAAoJENRtux+h35aGZ6cQALNrIXvCpEUfrLFAYgauJVWP 8cvu+gXUgCDxxcJR41MOBfDvnVOJmeiCJp0LWH3HpYGD0M+7BfJxMoyg/tdrZggn L5CSq+oXbeOUDe/7LV7E97u8/gZhHrRNELZGyWbgHX/d0VZpezH2QwMMQKTiwwAh zxkyUHyahJ1+Li6hrFL/1CI8XwH7JEnjgyd4Zfj2BNkkAmgS2E+iBrGYb8vMQtLo 7Pm6WBrTRjNNyrIKi6axHij2SvKdPKSzbAR3oJPjhL+5yDhrvCdHk0AvzJjiTHsK RMxaGYjR1/hRDt97+69iJu9hxjAOZSZeCYBid4vAPsdHu+qF/K5Ngr49rnWGFp9Y g8GkznO7q4L2Lde5WW0GRtNAGTgElEp+9cS1PSxDgyzxEw9+SaJUNLxr5cCsCp8I dI4Gu88gNgxT6AqomMcrIFd4LyHZ3HEW+rTuFcz4oCcmFQGXHqQVJQV6wbF1NpSf 8BuEskip4mTOdVvSfciC5jLjCO3q8xT/46TAYwhyrjUecEBR9FGy/e6ImN4DILiU nd8RvvTMKayAo3OudBcM/dN1YRzc0UijAqhFzV6/thvPNARGobGqzqwE3zKAseLY sPW1hKbJteDHHLBbG5Ia0/QyqdpXmSkyXjS8dahiuOefjuzWxeerGDaOl3wTiw/S o3J73WASesJ1RulPjqeW =M8Zh -----END PGP SIGNATURE----- -- 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
