[racket] typed racked questions

From: Bikal Gurung (gbikal at gmail.com)
Date: Mon Apr 30 17:23:01 EDT 2012


Is there a function in racket which will - given a name - display the
function/variable signature in the REPL?

I am thinking about haskell prelude(REPL) that gives me the type signature
when I enter :t <func name> in the repl?

With Thanks

On Mon, Apr 30, 2012 at 1:48 PM, Sam Tobin-Hochstadt <samth at ccs.neu.edu>wrote:

> On Mon, Apr 30, 2012 at 12:51 AM, Bikal Gurung <gbikal at gmail.com> wrote:
> > Hi All,
> >
> > I am investigating typed racket. I was wondering if someone could help
> with
> > answering the questions below.
> >
> > 1) Can we mix/import modules written in untyped racket to a module that
> is
> > used typed racket. I have experimented with a few modules using and they
> > seem to work in general but not really sure about the mechanism that
> makes
> > it work. How does racket make the untyped code and typed code work
> together
> > if they do? Is this in a case by case basis, ie. module/library by
> library
> > basis?
> Yes, you can mix typed modules and untyped modules in the same
> program.  This is one of the most fundamental features of Typed
> Racket.  To use a typed module from an untyped module, just require it
> -- contracts are inserted automatically to check the operation.  To
> use an untyped module from a typed module, use `require/typed' to
> specify the type.
> > 2) What is the canonical racket paradigm? use typed racket or untyped
> > racket? Or is this more an issue of a preference/style?
> This is very much an issue of style.  I think there are a number of
> advantages of type systems for maintenance, optimization,
> documentation, and organization, so I encourage you to use Typed
> Racket.  However, if you use plain Racket, Typed Racket is designed to
> make it easy to switch, a module at a time, when you decide you want
> types.
> > 3) Are typed racket programs faster than untyped ones? The documentation
> > says so but I was wondering if there has been any benchmark or study
> being
> > done on this topic.
> Yes, Typed Racket has an optimizing compiler (by Vincent St-Amour)
> which uses the type information to make your program go faster.  You
> can see some benchmark results in our papers
> http://www.ccs.neu.edu/racket/pubs/padl12-stff.pdf and
> http://www.ccs.neu.edu/racket/pubs/pldi11-thacff.pdf .
> > 4) Can typed racket module be used in the context of untyped racket
> module?
> Yes, you can just `require` the typed module, and it should work.
> > 5) Is there a Hindlye/Milner style type inferencing algorithm for typed
> > racket being worked on?
> The Typed Racket type system contains a number of features that go
> beyond what's supported in Hindley/Milner style type systems, and so
> we can't use that inference system.  Currently, Typed Racket uses
> local type inference to infer many of the types in your program, but
> we'd like to infer more of them -- this is an ongoing area of
> research.  However, inferring all the types in the program, the way
> that ML and Haskell do, is not a goal of Typed Racket -- having type
> annotations there makes the program self-documenting and easier to
> understand, improves type error messages, and supports advanced type
> system features.
> Thanks for your interest in Typed Racket, and if you have any more
> questions, please ask.
> --
> sam th
> samth at ccs.neu.edu
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