#13498: More storable instances? -------------------------------------+------------------------------------- Reporter: wyager | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 8.0.1 Resolution: | Keywords: Storable, | Foreign, Ptr Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by svenpanne): The reasoning why sum types have no `Storable` instance by default is that the encoding would be quite arbitrary. In your example: Why are the tags 8 bit wide, and why are the tag values `0` and `1`? Do we need a tag at all? For e.g. `Maybe (Ptr a)` a more common encoding is to have no tag at all and represent `Nothing` as a null pointer. For product types things are less arbitrary, but even then there is the issue of alignment. If you need serialization, you can use `Data.Binary`. I think we should close this ticket as `wontfix`, because the lack of these instances was a very deliberate decision. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13498#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler