Instances of `IsString`.

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Jason Dusek

20 Dec 2009 20 Dec '09

10:09 p.m.

A quick check on Hayoo! and in my interpreter shows that there are basically no instances of `IsString`. Is it really so little used? -- Jason Dusek

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Brandon S. Allbery KF8NH

20 Dec 20 Dec

10:12 p.m.

On Dec 20, 2009, at 17:09 , Jason Dusek wrote:

...

A quick check on Hayoo! and in my interpreter shows that there are basically no instances of `IsString`. Is it really so little used?

The only 2 instances I'm aware of are String and lazy and strict ByteStrings. It's not clear to me that there need to be any more (well, maybe the packed Unicode string package on hackage). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH

Antoine Latter

10:22 p.m.

On Sun, Dec 20, 2009 at 4:12 PM, Brandon S. Allbery KF8NH wrote:

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On Dec 20, 2009, at 17:09 , Jason Dusek wrote:

...
A quick check on Hayoo! and in my interpreter shows that there are basically no instances of `IsString`. Is it really so little used?

The only 2 instances I'm aware of are String and lazy and strict ByteStrings. It's not clear to me that there need to be any more (well, maybe the packed Unicode string package on hackage).

There's also ShowS and Text.PrettyPrint.Doc which make useful instances. The ShowS instance is a bit dicey since ShowS is just a type synonym. I don't know of any released packages which include these, though. I don't know if it would increase clarity, but I could see a Parsec instance as well, where fromString = string :: String -> Parser String. You could do the same for any of the parser combinator libraries I imagine. Antoine

Jason Dusek

10:39 p.m.

2009/12/20 Brandon S. Allbery KF8NH :

...

On Dec 20, 2009, at 17:09 , Jason Dusek wrote:

...
A quick check on Hayoo! and in my interpreter shows that there are basically no instances of `IsString`. Is it really so little used?

The only 2 instances I'm aware of are String and lazy and strict ByteStrings. It's not clear to me that there need to be any more (well, maybe the packed Unicode string package on hackage).

It could be easily abused, that is for sure. -- Jason Dusek

Neil Mitchell

23 Dec 23 Dec

9:33 p.m.

Hi Jason, I believe the original purpose of IsString was to enable writing of DSL's, much like described in this paper: http://portal.acm.org/citation.cfm?id=1411236 As such, you might find far more uses of IsString inside DSL's, some of which are likely to remain private. It was never designed to be a feature for every day use, but if you need it (as you do for Paradise) then it's hard to live without. Thanks, Neil On Sun, Dec 20, 2009 at 10:39 PM, Jason Dusek wrote:

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2009/12/20 Brandon S. Allbery KF8NH :

...
On Dec 20, 2009, at 17:09 , Jason Dusek wrote:

...
A quick check on Hayoo! and in my interpreter shows that there are basically no instances of `IsString`. Is it really so little used?

The only 2 instances I'm aware of are String and lazy and strict ByteStrings. It's not clear to me that there need to be any more (well, maybe the packed Unicode string package on hackage).

It could be easily abused, that is for sure.

-- Jason Dusek _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe