[erlang-questions] List comprehension puzzler

Hernando Gisinger <>
Tue Sep 20 05:01:45 CEST 2016


Hello

1> IsDigit = fun(C) -> C >= $0 andalso C =< $9 end.
#Fun<erl_eval.6.52032458>
2> S = "123a456".
"123a456"
3> [IsDigit(I) || I <- S].
[true,true,true,false,true,true,true]


2016-09-18 13:56 GMT-03:00 <>:

> Hello,
>
> Now this I would not expect:
>
> 4> S = "123a456".
> "123a456"
>
> 5> is_integer(S).
> false
>
> 6> [is_integer(I) || I <- S].
> [true,true,true,true,true,true,true]
>
> Please tell me what I don't understand.
>
> Many thanks,
>
> LRP
>
>
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