RE: Why doesn't GHC do the following optimisation?

It's a while since I paid serious attention to making sure that GHC's transformations are all working right. Things are usually more complicated than one might hope. In this case, * foldl is defined in the prelude using explicit recursion, as it happens * you've defined foldl' using foldr, and

Graphical Programming Environments (was: ANNOUNCE: Release of Vit al, an interactive visual programming environment for Haskell)

I've sometimes thought that a functional language would be the ideal platform to usher in a purely graphical style of programming; I don't understand why so many people talk about graphical programming, i.e. putting together functions, arguments, definitins etc. with the mouse

Hypothetical reasoning in type classes

Hello, Has anyone thought about adding hereditary Harrop formulas, in other words hypothetical reasoning and universal quantification, to the instance contexts in the Hsakell type class system? Just today (and not only today) I wanted to write instance definitions like instance (forall a. C

RE: Treating POSIX signals as exceptions?

There is a strong difference between asynchronous signals (like SIGIO, SIGINT, etc..) and synchronous ones (SIGFPE, SIGSEG). I think only the second type should be treated as exceptions, since they are tied to a specific thread of execution. tying asynchronous signals to exceptions just

Re: ANNOUNCE: Release of Vital, an interactive visual programming environment for Haskell

[Switching to haskell-cafe] For serious programming, I entirely agree. But my view is that we are seeing some degree of programmability entering all sorts of everyday objects -- video recorders spring to mind as an early example -- and there's lots of work going on in the field of ubiquitous

RE: ANNOUNCE: Release of Vital, an interactive visual programming environment for Haskell

As a serious programmer, I'd be very happy to have a more graphical, more interactive programming experience as far as _output_ is concern. I'm happy to input textual expressions and definitions, but I'd like instant feedback and display of intermediate results as tables, graphs, trees, charts

what's the deal with user error on fail?

When one triggers an exception with something like fail Error opening file The user gets a message like Fail: user error Reason: Error opening file which is confusing to the user, because it the user's fault. Is there some other way that it is recommended one fail? Or should I be catching

Re: Graphical Programming Environments (was: ANNOUNCE: Release of Vit al, an interactive visual programming environment for Haskell)

W licie z czw, 13-11-2003, godz. 10:34, [EMAIL PROTECTED] pisze: If 'graphical' isn't taken too literally, you can think of a dialog per function with the possibility to specify pre and post conditions, tests, comments, etc. I still doubt it would be more convenient. Maybe it's just me, but I

Re: Graphical Programming Environments (was: ANNOUNCE: Release of Vit al, an interactive visual programming environment for Haskell)

I love religious wars. Having been around awhile, I make a prediction. This will thrash a while, those who like graphical environments will make their points, those who like textual environments will make their points, no one will convince anyone else, and eventually it will die down. In fact

RE: Hypothetical reasoning in type classes

Yes, absolutely. See http://research.microsoft.com/~simonpj/Papers/derive.htm Section 7, and Trifanov's paper at the Haskell Workshop 2003 Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ken | Shan | Sent: 13 November 2003 05:40 | To:

Re: what's the deal with user error on fail?

hello, i would say that if you are wanting to report errors to users, you should not use fail or error. you should instead explicitly report the error. when i program i typically use error in situations that i think are imposible, but if there is a bug one gets a better error messeage. i don't

Re: ANNOUNCE: Release of Vital, an interactive visual programming environment for Haskell

Quoting Graham Klyne [EMAIL PROTECTED]: Finally, as evidence for this view of user interfaces, I note that for tasks like computer system administration, graphical interfaces have pretty much taken over from the old command-line-and-text-file approach. Even Linux systems have graphical

Re: what's the deal with user error on fail?

David Roundy [EMAIL PROTECTED] wrote: i would say that if you are wanting to report errors to users, you should not use fail or error. you should instead explicitly report the error. when i program i typically use error in situations that i think are imposible, but if there is a bug one

Sockets howto

Hello guys, any one aware of a Sockets howto for haskell ? Greets, Jad ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: what's the deal with user error on fail?

hello, well that's because haskell is not as pure as it claims to be :-) if every monad supports errors depends on what you mean by supporting errors. i would argue that supporting errors and divergence is not the same thing. the difference is that one should be able to handle an error thrown by

record matching syntax forensics

so I noticed DrIFT was generating code like f Foo{bar} = ... as seemingly a shorthand for f Foo{bar = bar} = ... which does not seem to work with current compilers. I fixed this in 2.0.2 but was curious why it was generating code like that in the first place. it appears to be illegal looking at

Re: record matching syntax forensics

Google for 'punning'. It was removed from Haskell (I don't know why -- look at the list archives). But that used to be legal. On Thu, 13 Nov 2003, John Meacham wrote: so I noticed DrIFT was generating code like f Foo{bar} = ... as seemingly a shorthand for f Foo{bar = bar} = ...

Re: what's the deal with user error on fail?

David Roundy [EMAIL PROTECTED] wrote: hello, well that's because haskell is not as pure as it claims to be :-) Nonsense. Haskell is perfectly pure; the IO monad is just nondeterministic :) if every monad supports errors depends on what you mean by supporting errors. I mean `supporting