[Haskell-cafe] Monad transformer responsibilities
deduktionstheorem at web.de
Mon Jun 8 07:06:30 EDT 2009
Henning Thielemann wrote:
>> - So you have to declare them near the test cases and they're orphan
>> The entire project doesn't issue a single warning when compiling with
>> -Wall *except* two orphan instances when building the test cases...
> However, I had sometimes the case, where a type from another library was
> part of my tests and thus I needed its Arbitrary instance. I could have
> defined instances for the foreign types, but they would have been orphan
> and I risk that the library author decides to add the instances later.
Hmm... maybe it is a good idea to aktivate the instance declaration with
a cabal flag? I've already got:
Description: Build a binary running test cases
and I could easily add something like
if flag( Test )
Build-Depends: QuickCheck >= 2 && < 3
data MyType = ...
instance Arbitrary MyType where
A usage of cabal flags that strongly reminds me of Gentoo's useflags :)
However, this will result in a total mess with more than one such flag...
Früher hieß es ja: Ich denke, also bin ich.
Heute weiß man: Es geht auch so.
- Dieter Nuhr
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