# [erlang-questions] Order of evaluation of guards

Danil Zagoskin z@REDACTED
Mon Jan 5 10:04:52 CET 2015

```Alternatively, you may split complex logic to several clauses:
f(N, M) when N > 100, M > 100 -> % Both too large
not_cool;
f(N, M) when N < 100, M < 100 -> % Both too small
not_cool;
f(N, M) when N > 0, M > 0 -> % Both are greater than 0, after previous
clauses exactly one of them greater than 100
cool;
f(_, _) ->
not_cool.

On Mon, Jan 5, 2015 at 11:51 AM, Martin Koroudjiev <mrtndimitrov@REDACTED>
wrote:

> Hello,
>
> First of all - Happy New Year!
>
> Suppose we have a function that accepts 2 integers and we want to react
> only when both integers are greater than 0 and one of them is less than
> 100:
>
> I tried:
> (dilbert@REDACTED)1> F = fun(N, M) when N > 0, M > 0, N < 100; M < 100
> -> cool; (_, _) -> not_cool end.
> #Fun<erl_eval.12.106461118>
> (dilbert@REDACTED)2> F(1,2).
> cool
> (dilbert@REDACTED)3> F(1,200).
> cool
> (dilbert@REDACTED)4> F(0,200).
> not_cool
> (dilbert@REDACTED)5> F(0,50).
> cool
>
> The last is not correct.
> What is the order of evaluation of the guards? Sadly parentheses are not
> allowed in guards.
>
> Best regards,
> Martin
>
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>

--
Danil Zagoskin | z@REDACTED
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