[racket] Typed Racket: Command-line parsing problems

Or maybe the expansion could be tweaked? (and a test case added?)

Robby


On Tue, Jun 25, 2013 at 10:50 AM, Sam Tobin-Hochstadt <samth at ccs.neu.edu>wrote:

> On Mon, Jun 24, 2013 at 8:21 AM, Matthias Felleisen
> <matthias at ccs.neu.edu> wrote:
> >
> > On Jun 23, 2013, at 8:34 PM, Sam Tobin-Hochstadt wrote:
> >
> >>>
> >>> After porting nearly everything I was left with typing up the
> command-line
> >>> parser. However, I am getting a type error at the following simplified
> part:
> >>
> >> Here's a version that type checks:
> https://gist.github.com/samth/5847063
> >>
> >> The key is giving a type annotation to `fname` using the #{} syntax.
> >> Typed Racket can figure out how to typecheck the expansion only if you
> >> give it that hint.  And the #{} syntax is for adding such hints with
> >> macros like `command-line` that didn't anticipate Typed Racket.
> >
> >
> > I think this answer is not fair.
> >
> > Because
> >
> > On Jun 23, 2013, at 2:21 PM, Tim K. wrote:
> >
> >> I wonder, why does fname have the "Any" type? Yes, I didn't explicitly
> give
> >> fname a type, but I was hoping that the typed version of "command-line"
> >> would do that
> >
> > is correct. command-line in a typed context should know that what flows
> into
> > its world is a string.
>
> This could mean one of two things.  One is that `command-line` could
> be treated specially in Typed Racket (or there's a
> `typed/racket/command-line` library), so that it's like those
> identifiers were already given the type `String`. This would be
> technically challenging (without requiring the extra library), and is,
> I think, a bad idea.  The other is that Typed Racket could improve its
> inference, so that it can just tell that only `String` is possible
> there.  This is my preferred solution, but it will require some
> significant work on improving inference in Typed Racket that I don't
> think will happen in the very near future.
>
> Sam
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