 Evaluation Order Semantics in Expressions with Side Effects
started 9/15/2002; 8:00:49 AM - last post 9/17/2002; 7:34:16 AM
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jon fernquest - Evaluation Order Semantics in Expressions with Side Effects 
9/15/2002; 8:00:49 AM (reads: 1837, responses: 3)
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| Evaluation Order Semantics in Expressions with Side Effects |
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The paper is a "step towards a complete and accurate
denotational description of ANSI C."
"ELSE", a simple eager expression language with side effects
and a subset of ANSI C expressions, is introduced to explore
"the denotational semantics of evaluation order."
Monads and monad transformers are used to modularly
introduce variations in evaluation order.
Several evaluation orders for "+" are implemented in
Haskell:
left-to-right evaluation (Java, ML),
non-deterministic choice,
interleaving,
evaluation in one atomic step,
and evaluation with ANSI C control points
which have a margin of semantic ambiguity
to implement optimizations in.
(A Study of Evaluation Order Semantics in Expressions with Side Effects,
NIKOLAOS S. PAPASPYROU, DRAGON MACOS, 2000)
Posted to implementation by jon fernquest on 9/15/02; 8:10:08 AM
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Ehud Lamm - Re: Evaluation Order Semantics in Expressions with Side Effects
9/16/2002; 1:32:16 PM (reads: 695, responses: 0)
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It is interesting to see how different language designers decided to define the order of evaluation of boolean expressions. Unspecified (most languages), short-circut (C), support for both short and long circut evaluation (Ada. When the non-short circut operators are used, the order of evaluation of the operands is unspecified).
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pixel - Re: Evaluation Order Semantics in Expressions with Side Effects
9/17/2002; 5:57:32 AM (reads: 689, responses: 1)
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Unspecified (most languages), short-circut (C), support for both short and
long circut evaluation
AFAIK short-circuit has won the game. It is the default for C, C#, Java,
JavaScript, OCaml, Haskell, Python, Perl...
more about it
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Ehud Lamm - Re: Evaluation Order Semantics in Expressions with Side Effects
9/17/2002; 7:34:16 AM (reads: 718, responses: 0)
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Vox populi vox dei? Come on!
When it comes to programming languages, popularity can be very misleading, as we all know.
Anyway, short circut doesn't go to well with operator overloading, so languages that support both often help you shoot yourself in the foot.
By the way, I wouldn't have included Haskell in the list you gave, seeing as it is uniformly lazy, and doesn't only short circut boolean expressions.
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