[erlang-questions] style question - best way to test multiple non-guard conditions sequentially

Richard A. O'Keefe <>
Fri Jun 21 01:45:15 CEST 2013


On 21/06/2013, at 4:27 AM, Jonathan Leivent wrote:
> OK - that is surprising.  That certainly changes my thinking about if statements.  Is this particular semantic difference between guards and general conditions ever expressed in the reference manual?  If so, I certainly missed it.

Yes it is.

Section 7.24 "Guard Sequences", where guards are described.

http://www.erlang.org/doc/reference_manual/expressions.html#id80042

At the end, there is this sentence:

	If an arithmetic expression, a boolean expression, a short-circuit
	expression, or a call to a guard BIF fails (because of invalid
	arguments), the entire guard fails . If the guard was part of
	a guard sequence, the next guard in the sequence (that is, the
	guard following the next semicolon) will be evaluated.


It's also explained clearly in the Erlang books I've read.




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