Hello everyone, Is there a way to automatically reify a type ? In other words, to do the following: reifyType (LitT ...) = ConT ''LitT ... I am using Template Haskell and I want the generated code to have access to Type datatypes that were available to the Template Haskell code. Cheers, Jose
Hello!
I'm not sure if this is what you're asking for, as it doesn't fit that line
of code. 'LitT' is a data constructor not a type constructor. So instead
it'd be
reifyType (LitT ...) = ConE 'LitT ...
If this is what you're looking for, then 'lift' is what you want:
http://hackage.haskell.org/packages/archive/th-lift/latest/doc/html/Language...http://hackage.haskell.org/packages/archive/th-lift/0.5.5/doc/html/Language-...
In particular, I recommend using this package of template haskell orphans,
rather than deriving your own: http://hackage.haskell.org/package/th-orphans
Hope that helps!
-Michael
On Fri, Jul 12, 2013 at 4:45 AM, Jose A. Lopes
Hello everyone,
Is there a way to automatically reify a type ? In other words, to do the following:
reifyType (LitT ...) = ConT ''LitT ...
I am using Template Haskell and I want the generated code to have access to Type datatypes that were available to the Template Haskell code.
Cheers, Jose
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Hello, I am getting the following error message: No instance for (Lift Type) arising from a use of `lift' Possible fix: add an instance declaration for (Lift Type) I have imported Language.Haskell.TH.Instances. Is there anything else I have to do ? Regards, Jose
You might need to cabal update - I recently uploaded a new version to
hackage, because I realized the package was a bit out of date from the
github repo.
It works for me: https://gist.github.com/mgsloan/f9238b2272df43e53896
On Fri, Jul 12, 2013 at 5:49 AM, Jose A. Lopes
Hello,
I am getting the following error message:
No instance for (Lift Type) arising from a use of `lift' Possible fix: add an instance declaration for (Lift Type)
I have imported Language.Haskell.TH.Instances. Is there anything else I have to do ?
Regards, Jose
participants (2)
-
Jose A. Lopes -
Michael Sloan