T15325.hs:11:7: warning: [-Wdeferred-type-errors (in -Wdefault)]
    • No instance for (PolyList e0) arising from a use of ‘f’
    • In the expression: f 0
      In an equation for ‘plh’: plh = f 0

T15325.hs:11:9: warning: [-Wdeferred-type-errors (in -Wdefault)]
    • Ambiguous type variable ‘e0’ arising from the literal ‘0’
      prevents the constraint ‘(Num e0)’ from being solved.
      Probable fix: use a type annotation to specify what ‘e0’ 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
        ...plus one instance involving out-of-scope types
        (use -fprint-potential-instances to see them all)
    • In the first argument of ‘f’, namely ‘0’
      In the expression: f 0
      In an equation for ‘plh’: plh = f 0
*** Exception: T15325.hs:11:7: error:
    • No instance for (PolyList e0) arising from a use of ‘f’
    • In the expression: f 0
      In an equation for ‘plh’: plh = f 0
(deferred type error)