Question

I have a little issue to which I can find no easy answer.

I set:

Who = apple.

Message = [{apple, {0,0,0}}, {orange, {1,1,1}}].

Old = [X || {Who, X} <- Message].

Old returns as [{0,0,0},{1,1,1}]

Of course my expected response was {0,0,0}

Instead I get both apple and orange.

What could I do??

Answer 1

Interesting question, I really liked that one! Looks like the scoping rules of Erlang are a bit odd (or at least I am not used to it, because I don’t use Erlang regularly)… But the following seems to work:

[Old|_] = [X || {W, X} <- Message, W =:= Who].