Matchure: Serious Clojure Pattern Matching

http://spin.atomicobject.com/2010/04/25/matchure-serious-clojure-pattern-matching?utm_source=social-media&utm_medium=social-media&utm_campaign=social-media

by atomicobject • 16 years ago

43 6 16 years ago

spin.atomicobject.com

floater• 16 years ago

Duplicate: http://news.ycombinator.com/item?id=1293600.

mnemonik2• 16 years ago

Maybe I missed this from the article, but it would be really cool if someone would mash this pattern matching up in a macro with defn (maybe called "?defn" or something) so you could do stuff like the following without relying on apply:

    (defn qsort
      ([] '())
      ([Head & Tail] (let [lower (filter #(< % Head) Tail)
                           upper (filter #(>= % Head) Tail)]
                       (concat (apply qsort lower) (list Head) (apply qsort upper)))))

I have barely played around with Clojure though, so if there is a nicer way to express that code, please drop a comment and try not to tear me to pieces. My point is that I would love to have pattern matching available in function definitions similar to Haskell/Erlang.

swannodette2• 16 years ago

You can handle your particular case with Clojure's fn argument destructuring. No need for pattern matching.

mnemonik2• 16 years ago

Thanks for the info, didn't know you could do that! What about the classic factorial, though?

  (defn factorial
    ([0] 1)
    ([x] (* x (factorial (- x 1)))))

dcolthorp• 16 years ago

Hey mnemonik. I had the same thought. It's in the todo in the readme on github.

Matchure: Serious Clojure Pattern Matching

Related Stories