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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2019-02-14 08:28:43 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2019-02-14 08:40:03 +0000 |
| commit | 5c1f268e2744fab2d36e64c163858995451d7095 (patch) | |
| tree | cb9b05c9112e6df43d90f28b6e3a252b2a077d46 /testsuite/tests/indexed-types | |
| parent | 682783828275cca5fd8bf5be5b52054c75e0e22c (diff) | |
| download | haskell-5c1f268e2744fab2d36e64c163858995451d7095.tar.gz | |
Fail fast in solveLocalEqualities
This patch makes us fail fast in TcSimplify.solveLocalEqualities,
and in TcHsType.tc_hs_sig_type, if there are insoluble constraints.
Previously we ploughed on even if there were insoluble constraints,
leading to a cascade of hard-to-understand type errors. Failing
eagerly is much better; hence a lot of testsuite error message
changes. Eg if we have
f :: [Maybe] -> blah
f xs = e
then trying typecheck 'f x = e' with an utterly bogus type
is just asking for trouble.
I can't quite remember what provoked me to make this change,
but I think the error messages are notably improved, by
removing confusing clutter and focusing on the real error.
Diffstat (limited to 'testsuite/tests/indexed-types')
| -rw-r--r-- | testsuite/tests/indexed-types/should_fail/T13877.stderr | 22 |
1 files changed, 2 insertions, 20 deletions
diff --git a/testsuite/tests/indexed-types/should_fail/T13877.stderr b/testsuite/tests/indexed-types/should_fail/T13877.stderr index 9dc8534ca1..674b258c24 100644 --- a/testsuite/tests/indexed-types/should_fail/T13877.stderr +++ b/testsuite/tests/indexed-types/should_fail/T13877.stderr @@ -1,25 +1,7 @@ -T13877.hs:65:17: error: - • Couldn't match type ‘Apply p (x : xs)’ with ‘p (x : xs)’ - Expected type: Sing x - -> Sing xs - -> App [a1] (':->) * p xs - -> App [a1] (':->) * p (x : xs) - Actual type: Sing x -> Sing xs -> (p @@ xs) -> p @@ (x : xs) - • In the expression: listElimPoly @(:->) @a @p @l - In an equation for ‘listElimTyFun’: - listElimTyFun = listElimPoly @(:->) @a @p @l - • Relevant bindings include - listElimTyFun :: Sing l - -> (p @@ '[]) - -> (forall (x :: a1) (xs :: [a1]). - Sing x -> Sing xs -> (p @@ xs) -> p @@ (x : xs)) - -> p @@ l - (bound at T13877.hs:65:1) - T13877.hs:65:41: error: • Expecting one more argument to ‘p’ - Expected kind ‘(-?>) [a1] * (':->)’, but ‘p’ has kind ‘[a1] ~> *’ + Expected kind ‘(-?>) [a] * (':->)’, but ‘p’ has kind ‘[a] ~> *’ • In the type ‘p’ In the expression: listElimPoly @(:->) @a @p @l In an equation for ‘listElimTyFun’: @@ -27,7 +9,7 @@ T13877.hs:65:41: error: • Relevant bindings include listElimTyFun :: Sing l -> (p @@ '[]) - -> (forall (x :: a1) (xs :: [a1]). + -> (forall (x :: a) (xs :: [a]). Sing x -> Sing xs -> (p @@ xs) -> p @@ (x : xs)) -> p @@ l (bound at T13877.hs:65:1) |