[Haskell-cafe] Need help from a newby

[Christopher L Conway]

Substitute the definition of type Table into the error:

Type error in explicitly typed binding
*** Term           : [(a,p)]
*** Type           : [(a,b)]
*** Does not match : [Table]

where [Table] = [[(Address,Port)]]

Do you see why the expression [ (a,p) ] cannot have type  [ [
(Address, Port) ] ] ?

Regards,
Chris

On 11/1/07, karle <ph_kittichai at yahoo.com> wrote:
>
> My declaration is as followed:-
>
> type Address = Int
> data Port = C | D deriving(Eq,Show)
> data Payload = UP[Char] | RTDP(Address,Port) deriving(Eq,Show)
> data Pkgtype = RTD | U deriving(Eq,Show)
> type Pkg = (Pkgtype,Address,Payload)
> type Table = [(Address,Port)]
>
>
> findport::[Pkg]->[Table]->[([Pkg],[Pkg])]
> findport [(pt,ad,pa)]  [(a,p)]
>       | ( p == C) = ([pt,ad,a],[])
>       | otherwise = ([],[pt,ad,a])
>
> Error received:-
>
> Type error in explicitly typed binding
> *** Term           : [(a,p)]
> *** Type           : [(a,b)]
> *** Does not match : [Table]
>
> Can anyone please help?
> --
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