OCaml: sakta men säkert.

A trie:

type lex_node = Letter of char * bool * lex_tree
and lex_tree = lex_node list;;

A function to test whether a word belongs in the dictionary (answer to an exercise from the book “Deploying Applications With Objective Caml”):

let exists word trie =
  let rec exists_aux acc nl =
    let exists_inner = function
      Letter(c,b,nl) -> let wc = (acc ^ (String.make 1 c))
                        in if b && (wc=word) then true
                           else exists_aux wc nl
    in List.exists exists_inner nl
  in exists_aux "" trie;;

Now working on “insert”.