[erlang-questions] Lists Comprehension issue?

[Bob Ippolito]

20 is not a list of lists.

On Wednesday, January 14, 2015, Carlos Suarez Fontalvo <
eng.carlos.suarez@REDACTED> wrote:

> Hi. I've reading this documentation:
> http://www.erlang.org/doc/programming_examples/list_comprehensions.html
>
> And it says that
>
> 3.5  Simplifications with List Comprehensions
>
> As an example, list comprehensions can be used to simplify some of the
> functions in lists.erl:
>
> append(L)   ->  [X || L1 <- L, X <- L1].
> map(Fun, L) -> [Fun(X) || X <- L].
> filter(Pred, L) -> [X || X <- L, Pred(X)].
>
> However when I tried to test this first example "append" doing something simple like this:
>
> 73> [X || L1 <- 20, X <- L1].
> ** exception error: bad generator 20
>
> I got a "exception error" message. Any idea why?. Am I not considering something?
>
> Thanks in advance
>
>
>
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