* For record selectors, currently written (x r), writing r.x is
exactly right
Algol 68 used 'x of r', which I always found rather readable.
COBOL has always used 'x of r' and 'x in r' with the same meaning.
BCPL uses 'f O§F r' which may I believe also be written 'f::r'.
Fortran uses 'r%x'.
Simon Peyton-Jones simo...@microsoft.com writes:
Personally I think there are strong advantages to .:
I'm sorry, but I don't see it. Function composition is one of /the/ most
central concepts to functionaly programming. Overloading dot further is
a terrible idea. I don't see why using it for
|* General Type Directed Name Resolution (GTDNR):
|For every function application f x in the program where f is a
|name, f is resolved based on the type of the argument x.
|
...
| You suggest that GTDNR might not be a good idea, well why not? One
| reason is that it can
GTDNR is what I really want anyway... whether or not it's possible. :-)
At any given time, importing everything unqualified from every module used by a
typical hs leads only to a handful of ambiguities. While the general case might
be intractable, real-world cases might be trivial.
Regards,
2009/11/18 Twan van Laarhoven twa...@gmail.com:
The TDNR proposal really tries to do two separate things:
1. Record syntax for function application.
The proposal is to tread x.f or a variation thereof the same as (f x)
2. Type directed name lookup.
The proposal is to look up
| The proposal has this sentence, apparently in reference to using
| qualified imports: This is sufficient, but it is just sufficiently
| inconvenient that people don't use it much. Does this mean qualified
| imports?
I clarified.
| One thing I'd really like that this would provide is shorter
Excerpts from Twan van Laarhoven's message of Thu Nov 19 00:59:25 +0100 2009:
Levi Greenspan wrote:
What's the status of the TDNR proposal [1]? Personally I think it is a
very good idea and I'd like to see it in Haskell'/GHC rather sooner
than later. Working around the limitations of the
Nicolas Pouillard wrote:
The TDNR proposal really tries to do two separate things:
1. Record syntax for function application.
The proposal is to tread x.f or a variation thereof the same as (f x)
It is more like (ModuleToGuess.f x) than (f x).
My point is that desugaring x.f to (f
Twan van Laarhoven wrote:
My point is that desugaring x.f to (f x) and treating some instances
of (f x) as (ModuleToGuess.f x) are two separate things. In the
current proposal these two are combined, but I see no reason to do so.
To be a bit more concrete, I would propose:
* General Type
| Simon, have you given any thought to how this interacts with type system
| extensions, in particular with GADTs and type families? The proposal relies
| on being able to find the type of a term but it's not entirely clear to me
| what that means. Here is an example:
|
| foo :: F Int - Int
| foo
November 2009 03:07
| To: Haskell Cafe
| Subject: Re: [Haskell-cafe] Status of TypeDirectedNameResolution proposal?
|
| Neil Brown wrote:
| Having skimmed the page, it seems like the re-use of . is one of the
| major difficulties of the proposal. Would it be possible to use -?
| It has been used
On 18/11/2009, at 21:10, Simon Peyton-Jones wrote:
Yes I think it can, although you are right to point out that I said nothing
about type inference. One minor thing is that you've misunderstood the
proposal a bit. It ONLY springs into action when there's a dot. So you'd
have to write
| Each 'foo' gives a type instance for TDNR_foo, mapping the type of the first
| argument to the type of that foo.
|
| Hmm... GHC doesn't allow this:
|
| type instance TDNR_foo () = forall a. () - a - a
|
| IIUC this restriction is necessary to guarantee termination. Given your
analogy,
|
You know, another solution to the records problem, which is not quite
as convenient but much simpler (and has other applications) is to
allow local modules.
module Foo where
module Bar where
data Bar = Bar { x :: Int, y :: Int }
module Baz where
data Baz = Baz { x :: Int, y :: Int }
The proposal has this sentence, apparently in reference to using
qualified imports: This is sufficient, but it is just sufficiently
inconvenient that people don't use it much. Does this mean qualified
imports? I use them exclusively, and I'd love it if everyone else
used them too.
Anyway, a
On Wed, Nov 18, 2009 at 3:53 PM, Evan Laforge qdun...@gmail.com wrote:
The proposal has this sentence, apparently in reference to using
qualified imports: This is sufficient, but it is just sufficiently
inconvenient that people don't use it much. Does this mean qualified
imports? I use them
On Wed, Nov 18, 2009 at 4:12 PM, Edward Kmett ekm...@gmail.com wrote:
Qualified imports are some times problematic when you need to work with
classes from the module. You can't define a member of two instances from
different two modules that define classes with conflicting member names.
This
Thanks! Learn something new every day. =)
-Edward Kmett
On Wed, Nov 18, 2009 at 4:29 PM, David Menendez d...@zednenem.com wrote:
On Wed, Nov 18, 2009 at 4:12 PM, Edward Kmett ekm...@gmail.com wrote:
Qualified imports are some times problematic when you need to work with
classes from the
Levi Greenspan wrote:
What's the status of the TDNR proposal [1]? Personally I think it is a
very good idea and I'd like to see it in Haskell'/GHC rather sooner
than later. Working around the limitations of the current record
system is one of my biggest pain points in Haskell and TDNR would be a
| What's the status of the TDNR proposal [1]? Personally I think it is a
| very good idea and I'd like to see it in Haskell'/GHC rather sooner
| than later. Working around the limitations of the current record
| system is one of my biggest pain points in Haskell and TDNR would be a
| major
I've added an informal straw poll to the bottom of [1] to allow you to
express an opinion.
[1]: ?
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Simon Peyton-Jones wrote:
| What's the status of the TDNR proposal [1]?
It's stalled. As far as I know, there's been very little discussion about it. It's not a trivial thing to implement, and it treads on delicate territory (how . is treated).
Having skimmed the page, it seems like the
On Tue, Nov 17, 2009 at 1:18 PM, Simon Peyton-Jones
simo...@microsoft.com wrote:
| What's the status of the TDNR proposal [1]? Personally I think it is a
| very good idea and I'd like to see it in Haskell'/GHC rather sooner
| than later. Working around the limitations of the current record
|
On Tue, Nov 17, 2009 at 1:18 PM, Simon Peyton-Jones
simo...@microsoft.com wrote:
I've added an informal straw poll to the bottom of [1] to allow you to
express an opinion.
Forgive my ignorance, but I can not find a way to edit the wiki page.
What am I doing wrong?
Cheers,
Levi
Am Dienstag 17 November 2009 15:36:52 schrieb Levi Greenspan:
As pointed out by others one may choose a different string instead of
. like - if this makes the implementation of TDNR feasible.
Or, if both of these strings would make the implementation awkward, one can
choose a
different but
On Tue, Nov 17, 2009 at 5:18 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
| What's the status of the TDNR proposal [1]? Personally I think it is a
| very good idea and I'd like to see it in Haskell'/GHC rather sooner
| than later. Working around the limitations of the current record
|
...@haskell.org
[mailto:haskell-cafe-boun...@haskell.org] On
| Behalf Of Luke Palmer
| Sent: 17 November 2009 17:08
| To: Simon Peyton-Jones
| Cc: Levi Greenspan; Haskell Cafe
| Subject: Re: [Haskell-cafe] Status of TypeDirectedNameResolution proposal?
|
| On Tue, Nov 17, 2009 at 5:18 AM, Simon Peyton-Jones
Neil Brown wrote:
Having skimmed the page, it seems like the re-use of . is one of the
major difficulties of the proposal. Would it be possible to use -?
It has been used for accessing members in C and C++, so it is not too
unusual a choice.
It's also the one that Perl went with.
It is
Simon, have you given any thought to how this interacts with type system
extensions, in particular with GADTs and type families? The proposal relies on
being able to find the type of a term but it's not entirely clear to me what
that means. Here is an example:
foo :: F Int - Int
foo :: Int -
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