Mon Dec 18 13:12:05 PST 2006 Manuel M T Chakravarty <[EMAIL PROTECTED]>
* Deriving for indexed data types
- This patch implements deriving clauses for data instance declarations
(toplevel and associated)
- Doesn't support standalone deriving. This could be easily supported,
but requires an extension of the syntax of standalone deriving clauses.
Bj[_\c3_][_\b6_]rn, fancy adding this?
- We cannot derive Typeable. This seems a problem of notation, more than
anything else. Why? For a binary vanilla data type "T a b", we would
generate an instance Typeable2 T; ie, the instance is for the constructor
alone. In the case of a family instance, such as (S [a] (Maybe b)), we
simply have no means to denote the associated constuctor. It appears to
require type level lambda - something like (/\a b. S [a] (Maybe b).
- Derivings are for *individual* family *instances*, not for entire families.
Currently, I know of no simple translation of class instances for entire
families to System F_C. This actually seems to be similar to implementing
open data types [_\c3_][_\a0_] la L[_\c3_][_\b6_]h & Hinze.
- This patch only covers data types, not newtypes.
M ./compiler/typecheck/TcDeriv.lhs -59 +111
M ./compiler/typecheck/TcEnv.lhs -1 +19
M ./compiler/types/FamInstEnv.lhs -2 +46
M ./compiler/types/Type.lhs +8
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