我正在尝试在 Quipper 中编译一个程序，Quipper 是来自该站点的官方量子编程语言：http: //mathstat.dal.ca/~selinger/quipper/
我无法编译它，我认为这一定是与 GHC 或 Haskell 相关的问题，因为 Quipper 本身没有突出的错误。
我使用以下命令编译我的程序：
cd ~/quipper-0.8/quipper/scripts/
sudo ./quipper ~/quipper-0.8/tests/name.hs
我收到的错误如下所示：
[13 of 21] Compiling Quipper.QData ( ../../quipper/Quipper/QData.hs, ../../quipper/Quipper/QData.o )
../../quipper/Quipper/QData.hs:965:20:
Could not deduce (QCType Bool Bool s0
~ QCType Int Bool (QCType Bit Bit s))
from the context (QData s)
bound by the type signature for
qdata_promote_c :: QData s =>
BType s -> CType s -> ErrMsg -> BType s
at ../../quipper/Quipper/QData.hs:965:20-71
NB: ‘QCType’ is a type function, and may not be injective
The type variable ‘s0’ is ambiguous
Expected type: BType s -> CType s -> ErrMsg -> BType s
Actual type: BType s0 -> CType s0 -> ErrMsg -> BType s0
In the ambiguity check for the type signature for ‘qdata_promote_c’:
qdata_promote_c :: forall s.
QData s =>
BType s -> CType s -> ErrMsg -> BType s
To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
In the type signature for ‘qdata_promote_c’:
qdata_promote_c :: (QData s) =>
BType s -> CType s -> ErrMsg -> BType s
中引用的代码行QData.hs如下所示：
-- | Like 'qdata_promote', except take a piece of classical data.
qdata_promote_c :: (QData s) => BType s -> CType s -> ErrMsg -> BType s
qdata_promote_c b c s = qdata_promote b q s where
q = qdata_map (shapetype_c c) map_qubit c
map_qubit :: Bit -> Qubit
map_qubit = const qubit
显然这是代码中唯一有问题的部分 in QData.hs，但是当我将其注释掉时，我得到了这个错误：
[13 of 21] Compiling Quipper.QData ( ../../quipper/Quipper/QData.hs, ../../quipper/Quipper/QData.o )
[14 of 21] Compiling Quipper.Generic ( ../../quipper/Quipper/Generic.hs, ../../quipper/Quipper/Generic.o )
../../quipper/Quipper/Generic.hs:257:13:
Not in scope: ‘qdata_promote_c’
Perhaps you meant one of these:
‘qdata_promote’ (imported from Quipper.QData),
‘qcdata_promote’ (imported from Quipper.QData)
如您所见，这一次它接受[13 of 21]但在 14 时中断，因为它取决于我注释掉的功能。当我尝试遵循它的建议并添加 AllowAmbiguousTypes 时：
sudo ./quipper ~/quipper-0.8/tests/name.hs -XAllowAmbiguousTypes
我得到更多的错误：
[13 of 21] Compiling Quipper.QData ( ../../quipper/Quipper/QData.hs, ../../quipper/Quipper/QData.o )
../../quipper/Quipper/QData.hs:966:25:
Could not deduce (QCType
Bool Bool (QCType Qubit Qubit (QCType Qubit Qubit s0))
~ QCType Int Bool (QCType Bit Bit s))
from the context (QData s)
bound by the type signature for
qdata_promote_c :: QData s =>
BType s -> CType s -> ErrMsg -> BType s
at ../../quipper/Quipper/QData.hs:965:20-71
NB: ‘QCType’ is a type function, and may not be injective
The type variable ‘s0’ is ambiguous
Expected type: BType s
Actual type: BType (HType Qubit s0)
Relevant bindings include
q :: HType Qubit s0 (bound at ../../quipper/Quipper/QData.hs:967:3)
c :: CType s (bound at ../../quipper/Quipper/QData.hs:966:19)
b :: BType s (bound at ../../quipper/Quipper/QData.hs:966:17)
qdata_promote_c :: BType s -> CType s -> ErrMsg -> BType s
(bound at ../../quipper/Quipper/QData.hs:966:1)
In the expression: qdata_promote b q s
In an equation for ‘qdata_promote_c’:
qdata_promote_c b c s
= qdata_promote b q s
where
q = qdata_map (shapetype_c c) map_qubit c
map_qubit :: Bit -> Qubit
map_qubit = const qubit
../../quipper/Quipper/QData.hs:967:30:
Could not deduce (QCType Bit Bit s0 ~ QCType Bit Bit s)
from the context (QData s)
bound by the type signature for
qdata_promote_c :: QData s =>
BType s -> CType s -> ErrMsg -> BType s
at ../../quipper/Quipper/QData.hs:965:20-71
NB: ‘QCType’ is a type function, and may not be injective
The type variable ‘s0’ is ambiguous
Expected type: CType s0
Actual type: CType s
Relevant bindings include
q :: HType Qubit s0 (bound at ../../quipper/Quipper/QData.hs:967:3)
c :: CType s (bound at ../../quipper/Quipper/QData.hs:966:19)
b :: BType s (bound at ../../quipper/Quipper/QData.hs:966:17)
qdata_promote_c :: BType s -> CType s -> ErrMsg -> BType s
(bound at ../../quipper/Quipper/QData.hs:966:1)
In the first argument of ‘shapetype_c’, namely ‘c’
In the first argument of ‘qdata_map’, namely ‘(shapetype_c c)’
../../quipper/Quipper/QData.hs:967:43:
Could not deduce (QCType Bit Bit (QCType Qubit Qubit s0)
~ QCType Bit Bit s)
from the context (QData s)
bound by the type signature for
qdata_promote_c :: QData s =>
BType s -> CType s -> ErrMsg -> BType s
at ../../quipper/Quipper/QData.hs:965:20-71
NB: ‘QCType’ is a type function, and may not be injective
The type variable ‘s0’ is ambiguous
Expected type: HType Bit s0
Actual type: CType s
Relevant bindings include
q :: HType Qubit s0 (bound at ../../quipper/Quipper/QData.hs:967:3)
c :: CType s (bound at ../../quipper/Quipper/QData.hs:966:19)
b :: BType s (bound at ../../quipper/Quipper/QData.hs:966:17)
qdata_promote_c :: BType s -> CType s -> ErrMsg -> BType s
(bound at ../../quipper/Quipper/QData.hs:966:1)
In the third argument of ‘qdata_map’, namely ‘c’
In the expression: qdata_map (shapetype_c c) map_qubit c
这一切都源于我上面引用的完全相同的行QData.hs。请注意，这些错误显然与我自己在name.hs.
我注意到这个网站没有得到 Quipper 的直接帮助（我已经给 Quipper 的负责人发了电子邮件但没有回复），但我很确定这是我编译它的方式的问题，因为这些错误消息不是来自 Quipper 而是来自 GHC 或 Haskell。
所以无论如何，任何有助于了解这一点的帮助将不胜感激，内森