Re: [Unicon-group] return and failure

[David.gamey]

Jafar, I wrote the test suite after thinking about documenting the return behaviour.  I realised that just saying it returned to the caller could also be misinterpreted. It returns the value or the failure to the caller.  Sort of deferring the failure or failing within the callers context ‎. David Sent from my BlackBerry 10 smartphone on the Rogers network. From: Jafar Al-Gharaibeh Sent: Tuesday, March 1, 2016 11:21 AM To: Steve Wampler Cc: David Gamey; unicon-group@lists.sourceforge.net; Art Eschenlauer Subject: Re: [Unicon-group] return and failure R3 and R4 are both consistent with Art's finding. Both failed _expression_ (1< 0) and (\&null) didn't stop "return" from exiting the function. In both cases the call to the function failed as a result of returning the result of a failed _expression_. --Jafar On Tue, Mar 1, 2016 at 10:06 AM, Steve Wampler <swamp...@noao.edu> wrote: Nice set of example. "fail" is equivalent to "return &fail" - that is, it exits the procedure or method with failure.  "&fail" simply fails in the current _expression_, forcing backtracking (if any sub-expressions are suspended, of course).  "return" bounds its _expression_ and produces as the outcome of the invocation the outcome of the evaluation of that _expression_, where an empty _expression_ evaluates to &null.  So "return" and "return &null" are equivalent. [Uh, that could have been worded better...] I think all of the procedure calls in the example code you have are consistent with that behavior. -- Steve Wampler -- swamp...@noao.edu The gods that smiled on your birth are now laughing out loud.

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