[GHC] #10697: Change template-haskell API to allow NOUNPACK, lazy annotations

[GHC]

#10697: Change template-haskell API to allow NOUNPACK, lazy annotations
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Template Haskell  |              Version:  7.10.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5290, #8347      |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by RyanGlScott:

Old description:

> Currently, the {{{template-haskell}}} API is lagging behind what is
> possible with GHC's strictness annotations in data types, especially
> since the advent of {{{StrictData}}}. Currently, {{{template-haskell}}}
> has {{{Strict}}}:
>
> {{{#!hs
> data Strict
>   = IsStrict
>   | NotStrict
>   | Unpacked
> }}}
>
> But it appears that there are actually nine different combinations of
> packedness and strictness annotations:
>
> {{{#!hs
> data A = A                     Int -- No unpackedness, no strictness
> data A = A                    !Int -- No unpackedness, strict
> data A = A                    ~Int -- No unpackedness, lazy
> data A = A {-# NOUNPACK #-} A  Int -- NOUNPACK, no strictness
> data A = A {-# NOUNPACK #-} A !Int -- NOUNPACK, strict
> data A = A {-# NOUNPACK #-} A ~Int -- NOUNPACK, lazy
> data A = A {-#   UNPACK #-} A  Int -- UNPACK, no strictness
> data A = A {-#   UNPACK #-} A !Int -- UNPACK, strict
> data A = A {-#   UNPACK #-} A ~Int -- UNPACK, lazy
> }}}
>
> It seems like the most consistent thing to do would be change
> {{{Strict}}} and add {{{Unpack}}} to the {{{template-haskell}}} API:
>
> {{{#!hs
> data Strict
>   = IsStrict
>   | NotStrict
>   | IsLazy
>
> data Unpack
>   = Unpack
>   | NoUnpack
>   | NotUnpacked
>
> type UnpackStrictType = (Unpack, Strict, Type)
>
> type VarUnpackStrictType = (Name, Unpack, Strict, Type)
> }}}
>
> And so on.

New description:

 Currently, the {{{template-haskell}}} API is lagging behind what is
 possible with GHC's strictness annotations in data types, especially since
 the advent of {{{StrictData}}}. Currently, {{{template-haskell}}} has
 {{{Strict}}}:

 {{{#!hs
 data Strict
   = IsStrict
   | NotStrict
   | Unpacked
 }}}

 But it appears that there are actually nine different combinations of
 packedness and strictness annotations:

 {{{#!hs
 data A = A                   Int -- No unpackedness, no strictness
 data A = A                  !Int -- No unpackedness, strict
 data A = A                  ~Int -- No unpackedness, lazy
 data A = A {-# NOUNPACK #-}  Int -- NOUNPACK, no strictness
 data A = A {-# NOUNPACK #-} !Int -- NOUNPACK, strict
 data A = A {-# NOUNPACK #-} ~Int -- NOUNPACK, lazy
 data A = A {-#   UNPACK #-}  Int -- UNPACK, no strictness
 data A = A {-#   UNPACK #-} !Int -- UNPACK, strict
 data A = A {-#   UNPACK #-} ~Int -- UNPACK, lazy
 }}}

 It seems like the most consistent thing to do would be change {{{Strict}}}
 and add {{{Unpack}}} to the {{{template-haskell}}} API:

 {{{#!hs
 data Strict
   = IsStrict
   | IsLazy
   | NoStrictAnnot

 data Unpack
   = Unpack
   | NoUnpack
   | NoUnpackAnnot

 type UnpackStrict        = (Unpack, Strict)
 type UnpackStrictType    = (UnpackStrict, Type)
 type VarUnpackStrictType = (Name, UnpackStrict, Type)

 type StrictType    = UnpackStrictType
 type VarStrictType = VarUnpackStrictType
 }}}

 And so on.

--

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10697#comment:2>
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