[erlang-questions] illegal guard expression for IF illegal guard expression for "if"

[Ahmed Omar]

Because "the guard expression must be guaranteed to be free of side
effects"
http://www.erlang.org/doc/reference_manual/expressions.html#id201090
So you are not allowed to have a function call there, except for allowed
BIFs that satisfy that condition


On Fri, Dec 2, 2011 at 10:30 AM, Barco You <barcojie@REDACTED> wrote:

> Why does the following expression got "illegal guard expression" when
> compiling:
> X = 0.5,
> if
>     random:uniform() < X ->      %error reported for this line
>            good;
>     true ->
>            bad
> end.
>
> But if I change it to following expression, it's ok:
> X = 0.5,
> Ran = random:uniform(),
> if
>     Ran < X ->
>            good;
>     true ->
>            bad
> end.
>
> BRs,
> Barco
>
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>


-- 
Best Regards,
- Ahmed Omar
http://nl.linkedin.com/in/adiaa
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