[erlang-questions] guards

Dave Pawson <>
Sat Jul 25 05:31:33 CEST 2009


2009/7/25 Michael Truog <>:
> - Can't use parentheses in guards
> - All the guards are in the erlang module and are explicitly documented
> as allowed in guard expressions
>  (usually is_something/1, erlang:length/1 works but supposedly is O(n),
> not O(1) like the others)
> - use "," for and, otherwise ";" for or... they evaluate in a sequential way

Thanks. Not clear in the book I'm using (uses guard(X,Y)  when ....
and ... or => etc.


> - Specifying the type in the function argument is always faster than
> adding a guard function for the type
>   (as seen in the "The is_record() guard" thread)

I'll go hunting!


regards



-- 
Dave Pawson
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