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RE: [Template-haskell] Re: template-haskell names in 6.3
by Simon Peyton-Jones 21 Dec '04

21 Dec '04

aha, that's a good question. Hmm. It probably ought to work (though it won't today). Would it make a difference? S | -----Original Message----- | From: Keean Schupke [mailto:k.schupke@imperial.ac.uk] | Sent: 21 December 2004 14:03 | To: Simon Peyton-Jones | Cc: template-haskell(a)haskell.org | Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | | So does this work? | | nameModule (mkName "Foo.Bar") | | Keean.

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RE: [Template-haskell] Re: template-haskell names in 6.3
by Simon Peyton-Jones 21 Dec '04

21 Dec '04

| As to exactly what I am trying to do, it is to take a string say "Test" | and prefix | it with qCurrentModule to give the global name, so that: So you can just say do { m <- qCurrentModule ; return (mkName (m ++ ".Test")) } Let's leave at that for now, if that does what you need. I'm very cautious about adding equalities on Names. You can always ask if m <- qCurrentModule if (m == nameModule ''Test) ... Simon | module Main | data X | | main = do | m <- qCurrentModule | if mkQualName m "X" == ''X -- IE I want to test if m.X is really | the same X as ''X | then putStrLn "Okay" | else putStrLn "Fail" | | | | Keean. | | Simon Peyton-Jones wrote: | | >Because they the two can behave differently in different contexts. It's | >like saying why doesn't 1==2 because in the context (\x. x>10) both give | >False! | > | >I feel I am missing the point you are trying to make. I thought I had | >it when I suggested mkQualName, and you said "that's exactly what I | >want". But you can define mkQualName easily: | > mkQualName m s = mkName (m ++ "." ++ s). | > | >Why don't you give a complete (but small) example of what you are trying | >to do? | > | >Simon | > | >| -----Original Message----- | >| From: Keean Schupke [mailto:k.schupke@imperial.ac.uk] | >| Sent: 21 December 2004 10:48 | >| To: Simon Peyton-Jones | >| Cc: template-haskell(a)haskell.org | >| Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | >| | >| Okay but: | >| | >| >module Foo where | >| > data Test | >| > | >| >module Bar | >| > import Foo | >| > | >| > test = (''Test == mkName "Foo.Test") | >| | >| Test (in this scope) is Foo.Test, so why shouldn't it equal | >| mkName "Foo.Test" ? | >| | >| Keean. | >| | >| | >| Simon Peyton-Jones wrote: | >| | >| >No, certainly not. | >| > | >| > ''Test :: Name | >| > is a lexically-scoped Name, indissolubly connected to whatever | >| >Test means | >| > in the original lexical scope it appeared in | >| > | >| > mkName "Foo.Test" :: Name | >| > is a dynamically-scoped Name, captured by whatever context it's | >| >spliced into. | >| > | >| >They aren't the same, and shouldn't be! | >| > | >| >Simon | >| > | >| >| -----Original Message----- | >| >| From: template-haskell-bounces(a)haskell.org | >| >[mailto:template-haskell-bounces@haskell.org] On | >| >| Behalf Of Keean Schupke | >| >| Sent: 21 December 2004 10:06 | >| >| To: Simon Peyton-Jones | >| >| Cc: template-haskell(a)haskell.org | >| >| Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | >| >| | >| >| I think I am already using that... I wasn't sure if the | >'module-part' | >| >of the | >| >| name was the same as in a global name generated from ''... is: | >| >| | >| >| module Foo | >| >| data Test | >| >| | >| >| mkName "Foo.Test" == ''Test -- is this true? | >| >| | >| >| Keean | >| >| | >| >| Simon Peyton-Jones wrote: | >| >| | >| >| >Keean | >| >| > | >| >| >I was half way through implementing this when I realised it's | >there | >| >| >already. If you say | >| >| > | >| >| > mkName "Foo.baz" | >| >| > | >| >| >you'll get a dynamically scoped qualified name, just as you want. | >| >| > | >| >| >Is that OK? | >| >| > | >| >| >Simon | >| >| > | >| >| >| -----Original Message----- | >| >| >| From: template-haskell-bounces(a)haskell.org | >| >| >[mailto:template-haskell-bounces@haskell.org] On | >| >| >| Behalf Of Keean Schupke | >| >| >| Sent: 03 December 2004 14:38 | >| >| >| To: Simon Peyton-Jones | >| >| >| Cc: template-haskell(a)haskell.org | >| >| >| Subject: Re: [Template-haskell] Re: template-haskell names in | >6.3 | >| >| >| | >| >| >| Simon Peyton-Jones wrote: | >| >| >| | >| >| >| >do you mean | >| >| >| > n <- newName s | >| >| >| >or | >| >| >| > let n = mkName s | >| >| >| >? | >| >| >| > | >| >| >| > | >| >| >| I mean the latter... or perhaps: "n <- return $ mkName s"... | >| >| >| | >| >| >| >If the latter, you will get | >| >| >| > data Foo = Foo Foo | >| >| >| > | >| >| >| >... and then I see what you want. You want a version of mkName | >| >that | >| >| >is | >| >| >| >like giving a qualified name in Haskell. It's dynamically | >scoped | >| >| >just | >| >| >| >like mkName, but it obeys the usual rules for qualified names | >in | >| >| >| >Haskell. | >| >| >| > | >| >| >| >To be totally explicit, suppose I have | >| >| >| > | >| >| >| > foo = [| mkQualName "Foo" "baz" |] | >| >| >| > | >| >| >| >then if I call foo thus | >| >| >| > | >| >| >| > wibble = \baz -> $foo | >| >| >| > | >| >| >| >the $foo splice will expand to "Foo.baz", and that won't see | >the | >| >| >\baz; | >| >| >| >it'll see whatever Foo.baz is in scope. | >| >| >| > | >| >| >| > | >| >| >| This is exactly what I am after... | >| >| >| | >| >| >| >Is that what you seek? I can see it's reasonable. I'd need to | >| >add | >| >| >| > | >| >| >| > mkQualName :: String -> String -> Name | >| >| >| > | >| >| >| >That'd mean an extra form of Name. Currently, if you say | >| >| >| > 'Foo.baz | >| >| >| >you'll get a Name whose nameModule isn't necessarily Foo... | >it'll | >| >be | >| >| >the | >| >| >| >module that baz was actually defined in. | >| >| >| > | >| >| >| > | >| >| >| I'll leave that up to you, I don't mind if this translation | >| >happens, | >| >| >as | >| >| >| long as it refers to the Foo.baz in dynamic scope the actuall | >name | >| >| >| can change. | >| >| >| | >| >| >| Keean | >| >| >| _______________________________________________ | >| >| >| template-haskell mailing list | >| >| >| template-haskell(a)haskell.org | >| >| >| http://www.haskell.org/mailman/listinfo/template-haskell | >| >| > | >| >| > | >| >| | >| >| _______________________________________________ | >| >| template-haskell mailing list | >| >| template-haskell(a)haskell.org | >| >| http://www.haskell.org/mailman/listinfo/template-haskell | >| > | >| > | > | > | > | | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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RE: [Template-haskell] Re: template-haskell names in 6.3
by Simon Peyton-Jones 21 Dec '04

21 Dec '04

Because they the two can behave differently in different contexts. It's like saying why doesn't 1==2 because in the context (\x. x>10) both give False! I feel I am missing the point you are trying to make. I thought I had it when I suggested mkQualName, and you said "that's exactly what I want". But you can define mkQualName easily: mkQualName m s = mkName (m ++ "." ++ s). Why don't you give a complete (but small) example of what you are trying to do? Simon | -----Original Message----- | From: Keean Schupke [mailto:k.schupke@imperial.ac.uk] | Sent: 21 December 2004 10:48 | To: Simon Peyton-Jones | Cc: template-haskell(a)haskell.org | Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | | Okay but: | | >module Foo where | > data Test | > | >module Bar | > import Foo | > | > test = (''Test == mkName "Foo.Test") | | Test (in this scope) is Foo.Test, so why shouldn't it equal | mkName "Foo.Test" ? | | Keean. | | | Simon Peyton-Jones wrote: | | >No, certainly not. | > | > ''Test :: Name | > is a lexically-scoped Name, indissolubly connected to whatever | >Test means | > in the original lexical scope it appeared in | > | > mkName "Foo.Test" :: Name | > is a dynamically-scoped Name, captured by whatever context it's | >spliced into. | > | >They aren't the same, and shouldn't be! | > | >Simon | > | >| -----Original Message----- | >| From: template-haskell-bounces(a)haskell.org | >[mailto:template-haskell-bounces@haskell.org] On | >| Behalf Of Keean Schupke | >| Sent: 21 December 2004 10:06 | >| To: Simon Peyton-Jones | >| Cc: template-haskell(a)haskell.org | >| Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | >| | >| I think I am already using that... I wasn't sure if the 'module-part' | >of the | >| name was the same as in a global name generated from ''... is: | >| | >| module Foo | >| data Test | >| | >| mkName "Foo.Test" == ''Test -- is this true? | >| | >| Keean | >| | >| Simon Peyton-Jones wrote: | >| | >| >Keean | >| > | >| >I was half way through implementing this when I realised it's there | >| >already. If you say | >| > | >| > mkName "Foo.baz" | >| > | >| >you'll get a dynamically scoped qualified name, just as you want. | >| > | >| >Is that OK? | >| > | >| >Simon | >| > | >| >| -----Original Message----- | >| >| From: template-haskell-bounces(a)haskell.org | >| >[mailto:template-haskell-bounces@haskell.org] On | >| >| Behalf Of Keean Schupke | >| >| Sent: 03 December 2004 14:38 | >| >| To: Simon Peyton-Jones | >| >| Cc: template-haskell(a)haskell.org | >| >| Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | >| >| | >| >| Simon Peyton-Jones wrote: | >| >| | >| >| >do you mean | >| >| > n <- newName s | >| >| >or | >| >| > let n = mkName s | >| >| >? | >| >| > | >| >| > | >| >| I mean the latter... or perhaps: "n <- return $ mkName s"... | >| >| | >| >| >If the latter, you will get | >| >| > data Foo = Foo Foo | >| >| > | >| >| >... and then I see what you want. You want a version of mkName | >that | >| >is | >| >| >like giving a qualified name in Haskell. It's dynamically scoped | >| >just | >| >| >like mkName, but it obeys the usual rules for qualified names in | >| >| >Haskell. | >| >| > | >| >| >To be totally explicit, suppose I have | >| >| > | >| >| > foo = [| mkQualName "Foo" "baz" |] | >| >| > | >| >| >then if I call foo thus | >| >| > | >| >| > wibble = \baz -> $foo | >| >| > | >| >| >the $foo splice will expand to "Foo.baz", and that won't see the | >| >\baz; | >| >| >it'll see whatever Foo.baz is in scope. | >| >| > | >| >| > | >| >| This is exactly what I am after... | >| >| | >| >| >Is that what you seek? I can see it's reasonable. I'd need to | >add | >| >| > | >| >| > mkQualName :: String -> String -> Name | >| >| > | >| >| >That'd mean an extra form of Name. Currently, if you say | >| >| > 'Foo.baz | >| >| >you'll get a Name whose nameModule isn't necessarily Foo... it'll | >be | >| >the | >| >| >module that baz was actually defined in. | >| >| > | >| >| > | >| >| I'll leave that up to you, I don't mind if this translation | >happens, | >| >as | >| >| long as it refers to the Foo.baz in dynamic scope the actuall name | >| >| can change. | >| >| | >| >| Keean | >| >| _______________________________________________ | >| >| template-haskell mailing list | >| >| template-haskell(a)haskell.org | >| >| http://www.haskell.org/mailman/listinfo/template-haskell | >| > | >| > | >| | >| _______________________________________________ | >| template-haskell mailing list | >| template-haskell(a)haskell.org | >| http://www.haskell.org/mailman/listinfo/template-haskell | > | >

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RE: [Template-haskell] Re: template-haskell names in 6.3
by Simon Peyton-Jones 21 Dec '04

21 Dec '04

No, certainly not. ''Test :: Name is a lexically-scoped Name, indissolubly connected to whatever Test means in the original lexical scope it appeared in mkName "Foo.Test" :: Name is a dynamically-scoped Name, captured by whatever context it's spliced into. They aren't the same, and shouldn't be! Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Keean Schupke | Sent: 21 December 2004 10:06 | To: Simon Peyton-Jones | Cc: template-haskell(a)haskell.org | Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | | I think I am already using that... I wasn't sure if the 'module-part' of the | name was the same as in a global name generated from ''... is: | | module Foo | data Test | | mkName "Foo.Test" == ''Test -- is this true? | | Keean | | Simon Peyton-Jones wrote: | | >Keean | > | >I was half way through implementing this when I realised it's there | >already. If you say | > | > mkName "Foo.baz" | > | >you'll get a dynamically scoped qualified name, just as you want. | > | >Is that OK? | > | >Simon | > | >| -----Original Message----- | >| From: template-haskell-bounces(a)haskell.org | >[mailto:template-haskell-bounces@haskell.org] On | >| Behalf Of Keean Schupke | >| Sent: 03 December 2004 14:38 | >| To: Simon Peyton-Jones | >| Cc: template-haskell(a)haskell.org | >| Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | >| | >| Simon Peyton-Jones wrote: | >| | >| >do you mean | >| > n <- newName s | >| >or | >| > let n = mkName s | >| >? | >| > | >| > | >| I mean the latter... or perhaps: "n <- return $ mkName s"... | >| | >| >If the latter, you will get | >| > data Foo = Foo Foo | >| > | >| >... and then I see what you want. You want a version of mkName that | >is | >| >like giving a qualified name in Haskell. It's dynamically scoped | >just | >| >like mkName, but it obeys the usual rules for qualified names in | >| >Haskell. | >| > | >| >To be totally explicit, suppose I have | >| > | >| > foo = [| mkQualName "Foo" "baz" |] | >| > | >| >then if I call foo thus | >| > | >| > wibble = \baz -> $foo | >| > | >| >the $foo splice will expand to "Foo.baz", and that won't see the | >\baz; | >| >it'll see whatever Foo.baz is in scope. | >| > | >| > | >| This is exactly what I am after... | >| | >| >Is that what you seek? I can see it's reasonable. I'd need to add | >| > | >| > mkQualName :: String -> String -> Name | >| > | >| >That'd mean an extra form of Name. Currently, if you say | >| > 'Foo.baz | >| >you'll get a Name whose nameModule isn't necessarily Foo... it'll be | >the | >| >module that baz was actually defined in. | >| > | >| > | >| I'll leave that up to you, I don't mind if this translation happens, | >as | >| long as it refers to the Foo.baz in dynamic scope the actuall name | >| can change. | >| | >| Keean | >| _______________________________________________ | >| template-haskell mailing list | >| template-haskell(a)haskell.org | >| http://www.haskell.org/mailman/listinfo/template-haskell | > | > | | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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RE: [Template-haskell] Re: template-haskell names in 6.3
by Simon Peyton-Jones 21 Dec '04

21 Dec '04

Keean I was half way through implementing this when I realised it's there already. If you say mkName "Foo.baz" you'll get a dynamically scoped qualified name, just as you want. Is that OK? Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Keean Schupke | Sent: 03 December 2004 14:38 | To: Simon Peyton-Jones | Cc: template-haskell(a)haskell.org | Subject: Re: [Template-haskell] Re: template-haskell names in 6.3 | | Simon Peyton-Jones wrote: | | >do you mean | > n <- newName s | >or | > let n = mkName s | >? | > | > | I mean the latter... or perhaps: "n <- return $ mkName s"... | | >If the latter, you will get | > data Foo = Foo Foo | > | >... and then I see what you want. You want a version of mkName that is | >like giving a qualified name in Haskell. It's dynamically scoped just | >like mkName, but it obeys the usual rules for qualified names in | >Haskell. | > | >To be totally explicit, suppose I have | > | > foo = [| mkQualName "Foo" "baz" |] | > | >then if I call foo thus | > | > wibble = \baz -> $foo | > | >the $foo splice will expand to "Foo.baz", and that won't see the \baz; | >it'll see whatever Foo.baz is in scope. | > | > | This is exactly what I am after... | | >Is that what you seek? I can see it's reasonable. I'd need to add | > | > mkQualName :: String -> String -> Name | > | >That'd mean an extra form of Name. Currently, if you say | > 'Foo.baz | >you'll get a Name whose nameModule isn't necessarily Foo... it'll be the | >module that baz was actually defined in. | > | > | I'll leave that up to you, I don't mind if this translation happens, as | long as it refers to the Foo.baz in dynamic scope the actuall name | can change. | | Keean | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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RE: FW: [Template-haskell] TH restrictions
by Simon Peyton-Jones 15 Dec '04

15 Dec '04

Ian, I don't think I understand what you are saying here. What is your number 1? Simon | -----Original Message----- | From: Ian Lynagh [mailto:ian@matrix.chaos.earth.li] On Behalf Of Ian Lynagh | Sent: 05 December 2004 03:03 | To: Simon Peyton-Jones; template-haskell(a)haskell.org | Subject: Re: FW: [Template-haskell] TH restrictions | | On Thu, Nov 18, 2004 at 01:15:25AM +0000, Ian Lynagh wrote: | > | > For what it's worth, I think one of the biggest irritations I've had | > with writing stuff using TH is the need to split things across module | > boundaries. | | Actually, I think this is number 2 on my list, below portability. | | As I said recently, I've hacked something I wrote to print out TH | generated code for use on a platform without ghci+TH, which is a pain | but not a showstopper for myself. | | However, I wanted to unroll the inner loop in SHA1 (essentially says "do | this for n = 0..79") for darcs, and really don't want it to get into the | situation of having to maintain generated code for platforms without | ghci+TH. So for the time being I have to leave it either in a slower HO | form or the fast but ugly hand-unrolled form. | | I appreciate that this is also a hard problem to solve; I just thought | I'd let you know it is an issue. | | (In general portability to other implementations may be an issue too, of | course, although darcs currently doesn't support them anyway) | | | Thanks | Ian

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RE: [Template-haskell] Re: Show Info
by Simon Peyton-Jones 15 Dec '04

15 Dec '04

Jim You need to update to the latest HEAD. Then it works. (But there was a missing case in pretty-printing for PrimTyConI which I fixed this morning, so "latest" means any time from now.) Simon | -----Original Message----- | From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On | Behalf Of Jim Apple | Sent: 14 December 2004 06:00 | To: template-haskell(a)haskell.org | Subject: [Template-haskell] Re: Show Info | | Jim Apple wrote: | > Is there any reason why Info isn't deriving(Show) ? | | Ok, I see from the testsuite examples and some code that I can print it | with pprint. I am now getting this new error: | | >$(do {display ''(->); [| () |]}) | | ghc-6.3.20041123: panic! (the `impossible' happened, GHC version | 6.3.20041123): | algTyConRhs GHCziPrim.ZLzmzgZR{(w) tc 3D} | | with display as in | | testsuite/tests/ghc-regress/th/TH_reifyDecl1.hs | | Jim | | _______________________________________________ | template-haskell mailing list | template-haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/template-haskell

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Using arrowT in a constructor class
by Peter Gammie 14 Dec '04

14 Dec '04

(I'm using GHC 6.2.2 on SPARC/Solaris.) I've got a class: class (Arrow arrow) => ArrowComb arrow b where or2 :: arrow (b, b) b ... and want to make an instance for it: data DCin b = MkDCin { field :: b } instance ArrowComb (->) b => ArrowComb (->) (DCin b) where or2 = ... using Template Haskell. Trying to use "arrowT" as a constructor in this context leads to the runtime error: *** Exception: hsSyn/Convert.lhs:317: Non-exhaustive patterns in function trans I can provide a test case if you need one. I don't have access to a CVS version, so this may already have been fixed. regards, Peter.

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Show Info
by Jim Apple 14 Dec '04

14 Dec '04

Is there any reason why Info isn't deriving(Show) ? Jim Apple

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FW: [Template-haskell] RE: calling fail in Q monad gives uninformativeerror message, anderror causes panic
by Simon Peyton-Jones 05 Dec '04

05 Dec '04

Dear Template Haskell colleagues I sent three messages to the TH list a month ago. Here's one of them: the others concerned the conversions TH.Syntax <-> HsSyn; I'll fwd them in the next two messages I didn't get a single reply to any of the three. Either the TH mailing list is broken, or else you are all busy with other stuff. (After all, all three did ask for volunteers, in one form or another.) Does anyone care? I'm busy implementing GADTs at the moment, so TH has a somewhat back seat. It'll probably stay that way unless there are some signs of life in the TH ranks. Simon -----Original Message----- From: template-haskell-bounces(a)haskell.org [mailto:template-haskell-bounces@haskell.org] On Behalf Of Simon Peyton-Jones Sent: 20 July 2004 12:19 To: Duncan Coutts; Template Haskell List Subject: [Template-haskell] RE: calling fail in Q monad gives uninformativeerror message, anderror causes panic Tim and I want to tidy up the error-reporting interface in Template Haskell. The goal is that a TH user should be able to control the error messages that appear. Here's a proposal qReport :: Severity -> String -> Q () -- Report an error or warning -- ...but carry on; use 'fail' to stop fail :: String -> Q a -- Part of Monad class qRecover :: (String -> [(Severity,Loc,String)] -> Q a) -> Q a -> Q a -- Recover from the monadic 'fail' -- The first arg is the error handler -- The first String arg to the handler is what was passed to 'fail' qReports :: [(Severity,Loc,String)] -> Q () data Severity = Error | Warning qGetLoc :: Q Loc qGetModule :: Q ModuleName qWithLoc :: Loc -> Q a -> Q a data Loc = Loc FileName LineNumber CharPos The idea is that qReport dumps a message into the monad (but does not print it yet) with an indication of severity. qReport does not cause monadic failure... you can dump in as many error messages as you like. qReport adds location information from the monad to the message. fail causes monadic failure. qRecover recovers from monadic failure, giving to the recovery routine both the string passed to fail, and the accumulated messages from the enclosed computation. It can use qReports to dump all those messages back into the monad -- or it can just discard them if it wants. At a splice point, the typechecker runs the Q computation. If the result is monadic success, it continues with the returned results. If the result is monadic failure, the splice fails too. (That does not result in any panic -- the type checker is designed to fail, and recover at some outer point.) In both cases, the messages from the Q monad are dumped into the typechecker's message pile. One open question. If you say qReport Error "Bad thing" fail "wuggle" in the Q monad, do you get two type error messages ("Bad thing" and "wuggle") or just one? I can think of three possibilities a) fail s is treated as adding an error message with Severity = Error b) fail s adds no error messages c) fail s behaves like (b) if (null s) and like (a) otherwise. The advantage of (b) and (c) is that you can add a whole bunch of error messages, and then fail, without adding yet another. Comments? Once we have an interface agreed, it won't be hard to implement. Simon | -----Original Message----- | From: glasgow-haskell-bugs-bounces(a)haskell.org [mailto:glasgow-haskell-bugs- | bounces(a)haskell.org] On Behalf Of Duncan Coutts | Sent: 23 June 2004 01:13 | To: glasgow-haskell-bugs(a)haskell.org | Subject: TH: calling fail in Q monad gives uninformative error message, anderror causes panic | | | ghc makes it's own type checker monad TcM an instance of the Quasi class | (which is rather cunning), however this means that if the user calls the | Monad function 'fail' then the internal TcM fail method gets called. | This monad (IOEnv) was never meant to fail (see | ghc/compiler/utils/IOEnv.hs/) so the error message is: | | Exception when trying to run compile-time code: | Code: genex_count | Exn: user error (IOEnv failure) | | Of course the user code should be using 'report', but if you're using | old code, or code that is generic in the monad it uses then people will | end up calling fail. | | Perhaps the thing to do is to wrap splices in an exception handler and | convert 'fail's into a 'report' instead. | | The same should probably be done for errors raised in pure code by | calling 'error'. At the moment it gives an overly panicky report | (although at least it passes the user's error message through): | | ghc-6.3: panic! (the `impossible' happened, GHC version 6.3): | where clauses & gaurds not yet supprted in function definitions | | The error message there is generated by my code (hence the spelling | errors :-) ). | | Duncan | | _______________________________________________ | Glasgow-haskell-bugs mailing list | Glasgow-haskell-bugs(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs _______________________________________________ template-haskell mailing list template-haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/template-haskell

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