On Friday, January 23, 2015 at 2:55:38 AM UTC+5:30, Ian wrote:
> On Thu, Jan 22, 2015 at 7:16 AM, Steven D'Aprano wrote:
> >> Meanwhile, there's the strange decision to implement type hints for
> >> local variables # comment lines. I have an hard time wrapping my head
> >> around this one. Really, comments!?
> >
> > Yes, really. There is plenty of prior art for machine-meaningful comments:
> >
> > - mypy uses it, and it works fine
> > - Pascal uses {$ ...} compiler directives
> > - Unix uses a special hash-bang #! comment in the first line to
> > specify the executable that runs the script
> > - Python supports a special encoding declaration using #
> > - doctest uses comments for directives
> > - HTML puts code (Javascript usually) inside of comments
> > - JMSAssert for Java uses comments for design-by-contract assertions
>
> Perhaps even more relevant to PEP 484:
>
> - The Closure compiler for Javascript uses JSDoc tags in comments for
> static typing and analysis.
I have not studied this carefully... so no opinion
However Peyton Jones is known to have said that for Haskell,
Haskell is on a Damas-Milner cusp -- basically if haskell's type system
becomes any more sophisticated, then automatic type inference becomes
undecidable
http://repository.upenn.edu/cgi/viewcontent.cgi?article=1336&context=cis_papers
Personally I find the predecessor of Haskell, gofer, prettier than Haskell
precisely because Haskell's type system has become too 'clever':
See my answer
http://stackoverflow.com/questions/25855507/are-typeclasses-essential
What has all this to do with python?? Dunno
Just that the 'optionality' of type-hinting may not be quite straightforward
================
PS Ian for a hot thread like this its good to put quotes carefully
You are quoting Steven quoting somebody -- dunno who that somebody is
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