On Friday, June 5, 2015 at 1:53:07 AM UTC-4, crocket wrote: > > Ouch, I didn't write. Gary Fredericks wrote it. I simply modified his > if-let-all macro a little bit. > > On Friday, June 5, 2015 at 2:44:22 PM UTC+9, crocket wrote: >> >> The macro below is called if-let-all. >> >> (defmacro if-let-all >> "if-let-all evaluates every local binding sequentially and evaluates >> true-case only if every local binding is a truthy value. >> true-case has access to all local bindings, but false-case doesn't have >> access to local bindings." >> [bindings true-case false-case] >> (let [pairs (partition 2 bindings) >> names (mapv first pairs) >> exprs (map second pairs) >> exprs-in-if-let (fn self [[name1 & more-names] [expr1 & more-exprs]] >> `(if-let [~name1 ~expr1] >> ~(if more-names >> (self more-names more-exprs) >> names))) >> things (exprs-in-if-let names exprs)] >> `(if-let [~names ~things] >> ~true-case >> ~false-case))) >> >> You can use it as (if-let-all [a 2 b 3] (+ a b) "oh no!!"). false-case >> doesn't have access to local bindings. >> >> Didn't I post something with a similar purpose a while back, called "if-and-let"? That one had some trickiness to avoid unexpectedly shadowing things unpredictably in false-case, as I recall.
-- 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/d/optout.
