Re: Generic instances for GHC AST

Hi Pedro That makes sense. I hit a mental block as to how to turn the generic representation back into the original type, but obviously if you know what you want to turn it into, the type-specific instance will be used. Alan On Fri, Feb 6, 2015 at 11:58 AM, José Pedro Magalhães wrote:

I have nothing against this.

If the unboxed types are a problem for the automatic Generic derivation, a manual instance could be written instead.

Cheers, Pedro

On Wed, Jan 14, 2015 at 9:03 PM, Alan & Kim Zimmerman

...

wrote:

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At the moment every part of the GHC AST derives instances of Data and Typeable.

There are no instances of Generic.

If I try to standalone derive these, the derivation eventually fails for

deriving instance Generic (Name)

because the constructors are not all in scope.

So, does it make sense in GHC to at least derive Generic for the items that are opaque, and at most to do so for the whole AST.

I know there were some concerns earlier about too many instances being derived, and its impact on compilation time and memory, so the minimal version may be best.

This will allow the new generation libraries built around Generics to perform on GHC data structures too.

Alan

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