GHC 8.2.1's typechecker rejects code generated by singletons that 8.0 accepts
I recently attempted to upgrade singletons to use GHC 8.2.1, but was thwarted when GHC's typechecker rejected code that was generated by Template Haskell. I was able to put all of this code in a single module (which I've attached), but sadly, it's 1367 lines long. What's important is that GHC 8.0.1 and 8.0.2 accept this code, but neither 8.2.1-rc1 nor HEAD do. Here is the error message you get, in its full glory:
$ /opt/ghc/8.2.1/bin/ghci Bug.hs -fprint-explicit-kinds
GHCi, version 8.2.0.20170403: http://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
[1 of 1] Compiling Bug ( Bug.hs, interpreted )
Bug.hs:1328:59: error:
• Couldn't match type ‘c69895866216793215480’ with ‘[a_a337f]’
‘c69895866216793215480’ is untouchable
inside the constraints: (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq)
bound by the type signature for:
lambda_a33iH :: forall (xs_a33fp :: [a_a337f]) (r_a33fq :: [[a_a337f]]).
(arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) =>
Sing [a_a337f] xs_a33fp
-> Sing [[a_a337f]] r_a33fq
-> Sing
[[a_a337f]]
(Apply
[[a_a337f]]
[[a_a337f]]
(Apply
[a_a337f]
(TyFun [[a_a337f]] [[a_a337f]] -> *)
(Let6989586621679736980InterleaveSym4
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33hh)
arg_a33hi)
at Bug.hs:(1289,35)-(1294,157)
Expected type: Sing (TyFun [a_a337f] [a_a337f] -> *) t
-> Sing [a_a337f] t1
-> Sing [[a_a337f]] t2
-> Sing
([a_a337f], [[a_a337f]])
((@@)
[[a_a337f]]
([a_a337f], [[a_a337f]])
((@@)
[a_a337f]
([[a_a337f]] ~> ([a_a337f], [[a_a337f]]))
((@@)
(TyFun [a_a337f] [a_a337f] -> *)
([a_a337f] ~> ([[a_a337f]] ~> ([a_a337f], [[a_a337f]])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
[a_a337f]
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
t)
t1)
t2)
Actual type: Sing (TyFun [a_a337f] c69895866216793215480 -> *) t
-> Sing [a_a337f] t1
-> Sing [c69895866216793215480] t2
-> Sing
([a_a337f], [c69895866216793215480])
(Apply
[c69895866216793215480]
([a_a337f], [c69895866216793215480])
(Apply
[a_a337f]
([c69895866216793215480] ~> ([a_a337f], [c69895866216793215480]))
(Apply
(TyFun [a_a337f] c69895866216793215480 -> *)
([a_a337f]
~> ([c69895866216793215480]
~> ([a_a337f], [c69895866216793215480])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
c69895866216793215480
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
t)
t1)
t2)
• In the second argument of ‘singFun3’, namely ‘sInterleave'’
In the first argument of ‘applySing’, namely
‘((singFun3
(Proxy ::
Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO)))
sInterleave')’
In the first argument of ‘applySing’, namely
‘((applySing
((singFun3
(Proxy ::
Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO)))
sInterleave'))
((singFun1 (Proxy :: Proxy IdSym0)) sId))’
• Relevant bindings include
sX_6989586621679737266 :: Sing
([a_a337f], [[a_a337f]])
(Let6989586621679737265X_6989586621679737266Sym6
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO
xs_a33fp
r_a33fq)
(bound at Bug.hs:1321:41)
r_a33iK :: Sing [[a_a337f]] r_a33fq (bound at Bug.hs:1295:57)
xs_a33iJ :: Sing [a_a337f] xs_a33fp (bound at Bug.hs:1295:48)
lambda_a33iH :: Sing [a_a337f] xs_a33fp
-> Sing [[a_a337f]] r_a33fq
-> Sing
[[a_a337f]]
(Apply
[[a_a337f]]
[[a_a337f]]
(Apply
[a_a337f]
(TyFun [[a_a337f]] [[a_a337f]] -> *)
(Let6989586621679736980InterleaveSym4
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33hh)
arg_a33hi)
(bound at Bug.hs:1295:35)
sR :: Sing [[a_a337f]] arg_a33hi (bound at Bug.hs:1287:45)
sXs :: Sing [a_a337f] arg_a33hh (bound at Bug.hs:1287:41)
sInterleave' :: forall (arg_a33he :: TyFun
[a_a337f] c69895866216793215480
-> *) (arg_a33hf :: [a_a337f]) (arg_a33hg :: [c69895866216793215480]).
Sing (TyFun [a_a337f] c69895866216793215480 -> *) arg_a33he
-> Sing [a_a337f] arg_a33hf
-> Sing [c69895866216793215480] arg_a33hg
-> Sing
([a_a337f], [c69895866216793215480])
(Apply
[c69895866216793215480]
([a_a337f], [c69895866216793215480])
(Apply
[a_a337f]
([c69895866216793215480] ~> ([a_a337f], [c69895866216793215480]))
(Apply
(TyFun [a_a337f] c69895866216793215480 -> *)
([a_a337f]
~> ([c69895866216793215480]
~> ([a_a337f], [c69895866216793215480])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
c69895866216793215480
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33he)
arg_a33hf)
arg_a33hg)
(bound at Bug.hs:1166:29)
lambda_a33ha :: Sing a_a337f t_a33aL
-> Sing [a_a337f] ts_a33aM
-> Sing [a_a337f] is_a33aO
-> Sing
[[a_a337f]]
(Apply
[a_a337f]
[[a_a337f]]
(Apply
[a_a337f]
([a_a337f] ~> [[a_a337f]])
(Let6989586621679736931PermsSym1 a_a337f xs0_a33a0)
arg_a33h0)
arg_a33h1)
(bound at Bug.hs:1153:23)
sTs :: Sing [a_a337f] n_a1kQd (bound at Bug.hs:1143:34)
sT :: Sing a_a337f n_a1kQc (bound at Bug.hs:1143:31)
lambda_a33gY :: Sing [a_a337f] xs0_a33a0
-> Sing
[[a_a337f]]
(Apply [a_a337f] [[a_a337f]] (PermutationsSym0 a_a337f) t_a33gX)
(bound at Bug.hs:1127:11)
(Some bindings suppressed; use -fmax-relevant-binds=N or -fno-max-relevant-binds)
|
1328 | sInterleave'))
| ^^^^^^^^^^^^
Bug.hs:1328:59: error:
• Could not deduce: (Let6989586621679736980Interleave'
[a_a337f]
[a_a337f]
a_a337f
c69895866216793215480
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO
t
t1
t2 :: ([a_a337f], [c69895866216793215480]))
~~
(Let6989586621679736980Interleave'
[a_a337f]
[a_a337f]
a_a337f
[a_a337f]
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO
t
t1
t2 :: ([a_a337f], [c69895866216793215480]))
from the context: t_a33gX ~ xs0_a33a0
bound by the type signature for:
lambda_a33gY :: forall (xs0_a33a0 :: [a_a337f]).
t_a33gX ~ xs0_a33a0 =>
Sing [a_a337f] xs0_a33a0
-> Sing
[[a_a337f]]
(Apply
[a_a337f] [[a_a337f]] (PermutationsSym0 a_a337f) t_a33gX)
at Bug.hs:(1122,11)-(1126,67)
or from: arg_a33h0 ~ (':) a_a337f n_a1kQc n_a1kQd
bound by a pattern with constructor:
SCons :: forall a_11 (z_a1kQb :: [a_11]) (n_a1kQc :: a_11) (n_a1kQd :: [a_11]).
z_a1kQb ~ (':) a_11 n_a1kQc n_a1kQd =>
Sing a_11 n_a1kQc -> Sing [a_11] n_a1kQd -> Sing [a_11] z_a1kQb,
in an equation for ‘sPerms’
at Bug.hs:1143:25-36
or from: (arg_a33h0
~
Apply
[a_a337f]
[a_a337f]
(Apply
a_a337f (TyFun [a_a337f] [a_a337f] -> *) ((:$) a_a337f) t_a33aL)
ts_a33aM,
arg_a33h1 ~ is_a33aO)
bound by the type signature for:
lambda_a33ha :: forall (t_a33aL :: a_a337f) (ts_a33aM :: [a_a337f]) (is_a33aO :: [a_a337f]).
(arg_a33h0
~
Apply
[a_a337f]
[a_a337f]
(Apply
a_a337f
(TyFun [a_a337f] [a_a337f] -> *)
((:$) a_a337f)
t_a33aL)
ts_a33aM,
arg_a33h1 ~ is_a33aO) =>
Sing a_a337f t_a33aL
-> Sing [a_a337f] ts_a33aM
-> Sing [a_a337f] is_a33aO
-> Sing
[[a_a337f]]
(Apply
[a_a337f]
[[a_a337f]]
(Apply
[a_a337f]
([a_a337f] ~> [[a_a337f]])
(Let6989586621679736931PermsSym1 a_a337f xs0_a33a0)
arg_a33h0)
arg_a33h1)
at Bug.hs:(1145,23)-(1152,117)
or from: (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq)
bound by the type signature for:
lambda_a33iH :: forall (xs_a33fp :: [a_a337f]) (r_a33fq :: [[a_a337f]]).
(arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) =>
Sing [a_a337f] xs_a33fp
-> Sing [[a_a337f]] r_a33fq
-> Sing
[[a_a337f]]
(Apply
[[a_a337f]]
[[a_a337f]]
(Apply
[a_a337f]
(TyFun [[a_a337f]] [[a_a337f]] -> *)
(Let6989586621679736980InterleaveSym4
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33hh)
arg_a33hi)
at Bug.hs:(1289,35)-(1294,157)
Expected type: Sing (TyFun [a_a337f] [a_a337f] -> *) t
-> Sing [a_a337f] t1
-> Sing [[a_a337f]] t2
-> Sing
([a_a337f], [[a_a337f]])
((@@)
[[a_a337f]]
([a_a337f], [[a_a337f]])
((@@)
[a_a337f]
([[a_a337f]] ~> ([a_a337f], [[a_a337f]]))
((@@)
(TyFun [a_a337f] [a_a337f] -> *)
([a_a337f] ~> ([[a_a337f]] ~> ([a_a337f], [[a_a337f]])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
[a_a337f]
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
t)
t1)
t2)
Actual type: Sing (TyFun [a_a337f] c69895866216793215480 -> *) t
-> Sing [a_a337f] t1
-> Sing [c69895866216793215480] t2
-> Sing
([a_a337f], [c69895866216793215480])
(Apply
[c69895866216793215480]
([a_a337f], [c69895866216793215480])
(Apply
[a_a337f]
([c69895866216793215480] ~> ([a_a337f], [c69895866216793215480]))
(Apply
(TyFun [a_a337f] c69895866216793215480 -> *)
([a_a337f]
~> ([c69895866216793215480]
~> ([a_a337f], [c69895866216793215480])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
c69895866216793215480
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
t)
t1)
t2)
The type variable ‘c69895866216793215480’ is ambiguous
• In the second argument of ‘singFun3’, namely ‘sInterleave'’
In the first argument of ‘applySing’, namely
‘((singFun3
(Proxy ::
Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO)))
sInterleave')’
In the first argument of ‘applySing’, namely
‘((applySing
((singFun3
(Proxy ::
Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO)))
sInterleave'))
((singFun1 (Proxy :: Proxy IdSym0)) sId))’
• Relevant bindings include
sX_6989586621679737266 :: Sing
([a_a337f], [[a_a337f]])
(Let6989586621679737265X_6989586621679737266Sym6
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO
xs_a33fp
r_a33fq)
(bound at Bug.hs:1321:41)
r_a33iK :: Sing [[a_a337f]] r_a33fq (bound at Bug.hs:1295:57)
xs_a33iJ :: Sing [a_a337f] xs_a33fp (bound at Bug.hs:1295:48)
lambda_a33iH :: Sing [a_a337f] xs_a33fp
-> Sing [[a_a337f]] r_a33fq
-> Sing
[[a_a337f]]
(Apply
[[a_a337f]]
[[a_a337f]]
(Apply
[a_a337f]
(TyFun [[a_a337f]] [[a_a337f]] -> *)
(Let6989586621679736980InterleaveSym4
[a_a337f]
[a_a337f]
a_a337f
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33hh)
arg_a33hi)
(bound at Bug.hs:1295:35)
sR :: Sing [[a_a337f]] arg_a33hi (bound at Bug.hs:1287:45)
sXs :: Sing [a_a337f] arg_a33hh (bound at Bug.hs:1287:41)
sInterleave' :: forall (arg_a33he :: TyFun
[a_a337f] c69895866216793215480
-> *) (arg_a33hf :: [a_a337f]) (arg_a33hg :: [c69895866216793215480]).
Sing (TyFun [a_a337f] c69895866216793215480 -> *) arg_a33he
-> Sing [a_a337f] arg_a33hf
-> Sing [c69895866216793215480] arg_a33hg
-> Sing
([a_a337f], [c69895866216793215480])
(Apply
[c69895866216793215480]
([a_a337f], [c69895866216793215480])
(Apply
[a_a337f]
([c69895866216793215480] ~> ([a_a337f], [c69895866216793215480]))
(Apply
(TyFun [a_a337f] c69895866216793215480 -> *)
([a_a337f]
~> ([c69895866216793215480]
~> ([a_a337f], [c69895866216793215480])))
(Let6989586621679736980Interleave'Sym4
[a_a337f]
[a_a337f]
a_a337f
c69895866216793215480
xs0_a33a0
t_a33aL
ts_a33aM
is_a33aO)
arg_a33he)
arg_a33hf)
arg_a33hg)
(bound at Bug.hs:1166:29)
lambda_a33ha :: Sing a_a337f t_a33aL
-> Sing [a_a337f] ts_a33aM
-> Sing [a_a337f] is_a33aO
-> Sing
[[a_a337f]]
(Apply
[a_a337f]
[[a_a337f]]
(Apply
[a_a337f]
([a_a337f] ~> [[a_a337f]])
(Let6989586621679736931PermsSym1 a_a337f xs0_a33a0)
arg_a33h0)
arg_a33h1)
(bound at Bug.hs:1153:23)
sTs :: Sing [a_a337f] n_a1kQd (bound at Bug.hs:1143:34)
sT :: Sing a_a337f n_a1kQc (bound at Bug.hs:1143:31)
lambda_a33gY :: Sing [a_a337f] xs0_a33a0
-> Sing
[[a_a337f]]
(Apply [a_a337f] [[a_a337f]] (PermutationsSym0 a_a337f) t_a33gX)
(bound at Bug.hs:1127:11)
(Some bindings suppressed; use -fmax-relevant-binds=N or -fno-max-relevant-binds)
|
1328 | sInterleave'))
| ^^^^^^^^^^^^