ABC problem: Difference between revisions

=={{header|Koka}}==

{{trans|Python}}with some Koka specific updates

<syntaxhighlight lang="koka">

val blocks = [("B", "O"),

("X", "K"),

("D", "Q"),

("C", "P"),

("N", "A"),

("G", "T"),

("R", "E"),

("T", "G"),

("Q", "D"),

("F", "S"),

("J", "W"),

("H", "U"),

("V", "I"),

("A", "N"),

("O", "B"),

("E", "R"),

("F", "S"),

("L", "Y"),

("P", "C"),

("Z", "M")]

pub fun get-remove( xs : list<a>, pred : a -> bool, acc: ctx<list<a>>) : (maybe<a>, list<a>)

match xs

Cons(x,xx) -> if !pred(x) then xx.get-remove(pred, acc ++ ctx Cons(x, _)) else (Just(x), acc ++. xx)

Nil -> (Nothing, acc ++. Nil)

fun check-word(word: string, blocks: list<(string, string)>)

match word.head

"" -> True

x ->

val (a, l) = blocks.get-remove(fn(a) a.fst == x || a.snd == x, ctx _)

match a

Nothing -> False

Just(_) -> check-word(word.tail, l)

fun can-make-word(word, blocks: list<(string, string)>)

check-word(word.to-upper, blocks)

fun main()

val words = ["", "a", "baRk", "booK", "treat", "COMMON", "squad", "Confused"]

words.map(fn(a) (a, can-make-word(a, blocks))).foreach fn((w, b))

println(w.show ++ " " ++ (if b then "can" else "cannot") ++ " be made")

</syntaxhighlight>

{{out}}

<pre>"": true

"" can be made

"a" can be made

"baRk" can be made

"booK" cannot be made

"treat" can be made

"COMMON" cannot be made

"squad" can be made

"Confused" can be made

</pre>