sebastiaanvisser/fclabels — pull request #11 by lunaris (2012-03-20 09:48:04+00:00)
Title: Make fclabels build with GHC HEAD

When trying to build on HEAD I receive errors such as:

```
src/Data/Label/Derive.hs:141:15:
Ambiguous constraint `Arrow t0'
At least one of the forall'd type variables mentioned by the constraint
must be reachable from the type after the '=>'
In the Template Haskell quotation
[t| Arrow $arrow =>
Lens $arrow $inputType $(return prettyFieldtyp) |]
In the third argument of `forallT', namely
`[t| Arrow $arrow =>
Lens $arrow $inputType $(return prettyFieldtyp) |]'
In the expression:
forallT
forallVars
(return [])
[t| Arrow $arrow =>
Lens $arrow $inputType $(return prettyFieldtyp) |]
```

Consequently I've patched the offending lines to use the functions of Language.Haskell.TH instead of the type quotations.