SML vs Ocaml for ECMA script spec.
dherman at ccs.neu.edu
Tue Oct 24 19:32:16 PDT 2006
> As for the style of the semantics. In an ideal world there would be a
> high-level "natural" big-step semantics. This big-step semanitcs is best
> for your "casual" progammer to undersand the spec. A very detaled
> "small-steps" semantics would be useful and avoid the need for adding
> things like threads/call-cc.
There's no reason a big-step operational semantics should be more
readable than an ML evaluator. We were heading in the direction of a
small-step semantics with explicit evaluation contexts, but decided that
a direct-style interpreter would be a bit more abstract and more accessible.
> Such a small-steps semantics maybe out of the charter of the current
> standard, but there is nothing preventing some energetic folks to
> maintain a small-step semantics in parallel with the "offical" spec. If
Yes, I've already prototyped a small-step semantics implemented in the
term rewriting language Stratego. One of the interesting side effects of
a small-step interpreter is that you get an automatic stepper
(debugger), as opposed to just an evaluator.
> the small-step semantics is more unambigous, one might consider that the
> "offical" spec and the big-step semantics the advisor commentary about
> it, or vice versa. But that decsion can be sorted out at the end of the
Well, no-- the working group has decided on ML as the spec language for
very good reasons we've already gone into. We aren't going to develop
two semantics in parallel on a tight deadline. :)
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