[ccing ghc-users]
| I'm trying to extract the names and types of exported functions in a module.
Quite a reasonable request. But it's not conveniently possible at the moment.
Here's what you can do in the Q monad:
class (Monad m, Functor m) => Quasi m where
-- Fresh names
qNewName :: String -> m Name
-- Error reporting and recovery
qReport :: Bool -> String -> m () -- Report an error (True) or warning
(False)
-- ...but carry on; use 'fail' to stop
qRecover :: m a -> m a -> m a -- Recover from the monadic 'fail'
-- The first arg is the error handler
-- Inspect the type-checker's environment
qReify :: Name -> m Info
qLocation :: m Loc
-- Input/output (dangerous)
qRunIO :: IO a -> m a
But you want one more function:
qReifyModule :: String -> m ModuleInfo
where ModuleInfo is something like:
data ModuleInfo = MI { mi_exports :: [Name]
, ... instances,rules, etc }
Then you could use qReify to get info about a particular thing.
This would not be hard in principle, the details need thought. For example, if
module exports T( C1, C2), where C1, C2 are constructors of T which also has
constructors C3, C4, what should appear in mi_exports? Should mi_exports
reflect the structure of the export list (see the AvailInfo type in GHC).
What is the info for an instance?
Do we need a way to ask for all the instances of a class (or rules for a
function) regardless of what module those instances come from? etc
Does this ring bells for anyone else? Would someone like to write the spec?
Are there other reify-related things that we need?
Simon
| -----Original Message-----
| From: template-haskell-boun...@haskell.org [mailto:template-haskell-
| boun...@haskell.org] On Behalf Of Oscar Finnsson
| Sent: 16 October 2009 18:47
| To: template-hask...@haskell.org
| Subject: [Template-haskell] How to extract name and type of exported
functions in
| modules
|
| Hi,
|
| I'm trying to extract the names and types of exported functions in a module.
|
| At the moment I've managed to get a list of all functions in a module
| but I can't seem to figure out how to get their types.
|
| Lets say I got the module
|
| module Foo where
|
| foo1 :: String -> String
| foo1 value = value
|
| foo2 = "hej"
|
| and then in anothor module...
|
| module Bar where
|
| bar = $(getAllFunctions "<some-path>/Foo.hs")
|
| At the moment I got getAllFunctions returning ["foo1","foo2"], but I
| would really like to get it to return [("foo1",AppT (ConT "String")
| (ConT "String")), ("foo2",ConT "String")]
|
| Using "parseModuleWithMode" from Language.Haskell.Exts I can get hold
| of the names and the type signature of foo1 (since it's specified in
| the source code) but I cannot get hold of the type signature of foo2
| (since it's not specified in the source code).
|
| Is there another way to get the names/signatures of exported functions
| from a module other than using parseModuleWithMode so the developer
| writing the Foo-module isn't forced to explicitly supply type
| signatures of the exported functions?
|
| If I try "reify" to get information about the functions I get the error
message:
| "foo1 is not in scope at a reify"
|
| This seems to be a known bug about reify (reported here
| http://hackage.haskell.org/trac/ghc/ticket/2339). My problem is that I
| cannot use the workaround since I don't know the name of the
| functions.
|
| Another disadvantage with this approach is that "getAllFunctions" must
| have access to the source code of the module and that I must supply
| the path the the module. If possible I would like to have code such as
|
| bar = $(getAllFunctions "Foo")
|
| instead of "<come-path>/Foo.hs".
|
| Regards,
| Oscar Finnsson
| _______________________________________________
| template-haskell mailing list
| template-hask...@haskell.org
| http://www.haskell.org/mailman/listinfo/template-haskell
_______________________________________________
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
