blob: a3a7ba3baef2f7fcd7a927326b9483037eca042c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
T13292a.hs:4:12: warning: [-Wdeferred-type-errors (in -Wdefault)]
• Ambiguous type variable ‘m0’ arising from a use of ‘return’
prevents the constraint ‘(Monad m0)’ from being solved.
Relevant bindings include
someFunc :: m0 () (bound at T13292a.hs:4:1)
Probable fix: use a type annotation to specify what ‘m0’ should be.
These potential instances exist:
instance Monad IO -- Defined in ‘GHC.Base’
instance Monad Maybe -- Defined in ‘GHC.Base’
instance Monoid a => Monad ((,) a) -- Defined in ‘GHC.Base’
...plus four others
...plus two instances involving out-of-scope types
(use -fprint-potential-instances to see them all)
• In the expression: return ()
In an equation for ‘someFunc’: someFunc = return ()
T13292.hs:6:1: warning: [-Wdeferred-type-errors (in -Wdefault)]
• Couldn't match type ‘GHC.Types.Any’ with ‘IO’
Expected: IO ()
Actual: GHC.Types.Any ()
• When checking the type of the IO action ‘main’
T13292.hs:6:1: warning: [-Wdeferred-type-errors (in -Wdefault)]
• Couldn't match type ‘GHC.Types.Any’ with ‘IO’
Expected: IO ()
Actual: GHC.Types.Any ()
• In the expression: main
When checking the type of the IO action ‘main’
|