Skip to content

WIP: Small refactor of internal data structures.

Andreas Klebinger requested to merge AndreasK/ghc:move_data_structs into master

GHC internal data types are currently a bit of a mess.

In particular there is a certain growth of Set/Map types, all doing the same thing but often providing different interfaces without good reason.
While there are reasons to chose insert over add over plus for adding an element to a data structure there is no reason to use all three in the same codebase.

Some examples taken from EnumSet/VarSet:

  • fromList :: Enum a => [a] -> EnumSet a
  • mkDVarSet :: [Var] -> DVarSet
  • toList :: Enum a => EnumSet a -> [a]
  • dVarSetElems :: DVarSet -> [Var]
  • extendVarSet :: VarSet -> Var -> VarSet
  • insert :: Enum a => a -> EnumSet a -> EnumSet a

There will always be certain type specific parts of a interface like lookupVarSetByName.
But I don't see why we shouldn't try to standardize somewhat the core operations on the Set/Map types.

This patch is however only a start and not a solution. It does:

  • Remove a few unused types
  • Make IsSet*/IsMap* more wildly useable as a common interface to the different Set/Map types by pulling it out of Hoop.
  • Move generic data structures into their own folder from util.
  • Move EnumSet over to the IsSet interface.
  • Split IsSet into a base clase and deterministic and non-deterministic subclasses.
Edited by Andreas Klebinger

Merge request reports