[erlang-questions] conditional expressions
Tue Nov 18 22:52:24 CET 2008
On 18 Nov 2008, at 4:38 pm, Serge Aleynikov wrote:
> Your 'must' statement is not entirely accurate.
Was there any doubt about what I meant?
Let's try again:
both 'andalso' and 'orelse' in Erlang have the
the first operand must either return 'true' or 'false'
or raise an exception;
the second operand, if executed, must either return
'true' or 'false' or raise an exception;
the Dialyzer will complain if either operand looks
as if it will return something other than 'false' or 'true';
and above all:
you CANNOT use them to get the same effect as
Lisp's (OR - -) and (AND - -) or Python's similar
operators, which allow a normal result from the
second operand to be anything at all.
I have in fact complained about this, not because I particularly
want non-Boolean results from these operators, but because the
code that's inserted to check makes them non-tail-recursive.
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