[Template-haskell] Re: template-haskell names in 6.3

[Simon Peyton-Jones]

| 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 at imperial.ac.uk]
| >| Sent: 21 December 2004 10:48
| >| To: Simon Peyton-Jones
| >| Cc: template-haskell at 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 at haskell.org
| >| >[mailto:template-haskell-bounces at haskell.org] On
| >| >| Behalf Of Keean Schupke
| >| >| Sent: 21 December 2004 10:06
| >| >| To: Simon Peyton-Jones
| >| >| Cc: template-haskell at 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 at haskell.org
| >| >| >[mailto:template-haskell-bounces at haskell.org] On
| >| >| >| Behalf Of Keean Schupke
| >| >| >| Sent: 03 December 2004 14:38
| >| >| >| To: Simon Peyton-Jones
| >| >| >| Cc: template-haskell at 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 at haskell.org
| >| >| >| http://www.haskell.org/mailman/listinfo/template-haskell
| >| >| >
| >| >| >
| >| >|
| >| >| _______________________________________________
| >| >| template-haskell mailing list
| >| >| template-haskell at haskell.org
| >| >| http://www.haskell.org/mailman/listinfo/template-haskell
| >| >
| >| >
| >
| >
| >
| 
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