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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