kata2-erlang

gistfile1.erl

-module(kata2).
-export([chop/0, chop/2]).
% http://stackoverflow.com/questions/1035655/list-is-conceived-as-integer-by-length-function


chop() -> chop(6,[2,4,6,8,10]).
chop(Result) -> io:format("Location index... ~w~n", [Result-1]).
chop(Val, List) ->
  if List == [] ->
    -1;
    true -> chop(Val, 1, length(List), List)
  end.

check_shit(Val, [L|L_val], [R|R_val]) ->
  X = if [Val] == L_val -> L;
         [Val] == R_val -> R;
         true -> 0
  end.

chop(Val, L, R, List) ->
  io:format("Chopping stuff"),
  Mid = round((L+R)/2),
  MidVal = lists:nth(Mid, List),

  if R-L == 1 ->
    Result = check_shit(Val, [L, lists:nth(L,List)], [R, lists:nth(R,List)]),
    chop(Result);
    true -> io:format(".")
  end,

  if Val =< MidVal ->
    chop(Val, L, Mid, List);
  true ->
    chop(Val, Mid, R, List)
  end.

I think you could use pattern matching to handle the empty list case (instead of handling with an if statement). Something like this:

% definition
chop(Val, []) -> -1

% usage
chop(1, []) => -1