Hello !
I think, this branch (without :<< empty?))
(match [l prefix]
* [_ ([] :seq)] true*
is already checking that prefix is empty.
Have a nice day,
Jon
On 16 July 2015 at 23:06, Rastko Soskic <rss...@gmail.com> wrote:
> Hi, I am getting familiar with Clojure's core.match and
> simply starting with something simple and familar (some Scala match
> expressions)
> and translating that to core.match variant:
> Check out this function which checks whether sequence starts with another:
>
> def startsWith[A](l: List[A], prefix: List[A]): Boolean = (l,prefix) match
> {
> case (_,Nil) => true
> case (Cons(h,t),Cons(h2,t2)) if h == h2 => startsWith(t, t2)
> case _ => false
> }
>
> and my core.match attempt which works but I am not really sure
> about it as wiki page is not yet exhaustive enough:
>
> (defn starts-with [l prefix]
> (match [l prefix]
> * [_ ([] :seq :<< empty?)] true*
> [([h & t] :seq) ([h2 & t2] :seq)] (if (= h h2)
> (starts-with t t2)
> false)
> :else false))
>
> second and third one are nothing special, former is just match
> continuation.
> First one is of particular interest for me...
> Matching to Nil sequence in clojure is not appropriate as empty sequence
> simply is not nil
> whereas it is handled differently in scala.
>
> What I wanted here is to check with empty? function if second argument
> (prefix)
> is empty sequence... Like I said...it works but I am not sure if there is
> better
> way to achieve function application to :seq pattern. I don't need to
> destructure or bind
> that to any particular var just to check if it is empty.
>
> Any tip, suggestion or critic is welcome and appreciated.
>
> Thanks in advance.
>
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