[1 of 1] Compiling Main ( prog.hs, prog.o )
prog.hs:5:8: error:
• No instance for (Num (IO a0)) arising from the literal ‘5’
• In a stmt of a 'do' block: a <- 5
In the expression:
do { a <- 5;
b <- 8;
print $ mygcd (a, b) }
In an equation for ‘main’:
main
= do { a <- 5;
b <- 8;
print $ mygcd (a, b) }
prog.hs:7:3: error:
• Ambiguous type variable ‘a0’ arising from a use of ‘print’
prevents the constraint ‘(Show a0)’ from being solved.
Relevant bindings include
b :: a0 (bound at prog.hs:6:3)
a :: a0 (bound at prog.hs:5:3)
Probable fix: use a type annotation to specify what ‘a0’ should be.
These potential instances exist:
instance Show Ordering -- Defined in ‘GHC.Show’
instance Show Integer -- Defined in ‘GHC.Show’
instance Show a => Show (Maybe a) -- Defined in ‘GHC.Show’
...plus 22 others
...plus five instances involving out-of-scope types
(use -fprint-potential-instances to see them all)
• In a stmt of a 'do' block: print $ mygcd (a, b)
In the expression:
do { a <- 5;
b <- 8;
print $ mygcd (a, b) }
In an equation for ‘main’:
main
= do { a <- 5;
b <- 8;
print $ mygcd (a, b) }
prog.hs:7:11: error:
• Ambiguous type variable ‘a0’ arising from a use of ‘mygcd’
prevents the constraint ‘(Num a0)’ from being solved.
Relevant bindings include
b :: a0 (bound at prog.hs:6:3)
a :: a0 (bound at prog.hs:5:3)
Probable fix: use a type annotation to specify what ‘a0’ should be.
These potential instances exist:
instance Num Integer -- Defined in ‘GHC.Num’
instance Num Double -- Defined in ‘GHC.Float’
instance Num Float -- Defined in ‘GHC.Float’
...plus two others
(use -fprint-potential-instances to see them all)
• In the second argument of ‘($)’, namely ‘mygcd (a, b)’
In a stmt of a 'do' block: print $ mygcd (a, b)
In the expression:
do { a <- 5;
b <- 8;
print $ mygcd (a, b) }