Chapter 3 flatten exercise -- can be identify a list via pattern matching?

[Hugo Estrada]

Hi there,

i am working on the exercise on chapter 3 and I am to the one where
one is supposed to flatten a list with nested elements.

It seems to me that I must identify if the head element that I am
handling at that moment is a list or not. I know that there is a
predicate, is_list/1, that will do this for me.

Am I suppose to use the predicate, or is there a pattern matching that
can tease out if the current H is a list or not?

Thanks for the good exercises, by the way. It actually makes one
really learn the language.

Thanks in advance for future answers,

Hugo

[Andrey]

It is possible to solve this exercise using only recursion and pattern
matching. You just need to define correct order of patterns.

Andrey

[Hugo Estrada]

Thanks! I will try to solve it with pattern matching then :)

--
Erlang Programming Website:
http://www.erlangprogramming.org/

[Sami]

You can test against the pattern [H|N]:
flatten([[H|T1]|T2]) -> concatenate([flatten([H|T1]), flatten(T2)]).

Sami