Thanks for the reply, David.
I tried implementing your suggestions, such that my code now looks like this:
1 -- Taken from `Programming with Arrows'.
2
3 module SF where
4
5 import Prelude hiding ((.),id)
6 import Control.Category
7 import Control.Arrow
8
9 newtype SF a b = SF {runSF :: [a] -> [b]}
10
11 instance Category SF
12
13 instance Arrow SF where
14 arr f = SF (map f)
15 SF f >>> SF g = SF (f >>> g)
but I'm getting the same error as before:
GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :load SF
[1 of 1] Compiling SF ( SF.hs, interpreted )
SF.hs:15:10: `>>>' is not a (visible) method of class `Arrow'
Failed, modules loaded: none.
Any thoughts?
Thanks,
-db
On Thu, Oct 27, 2011 at 8:29 AM, David Barbour <dmbarb...@gmail.com> wrote:
>
> On Thu, Oct 27, 2011 at 5:55 AM, Captain Freako <capn.fre...@gmail.com>
> wrote:
>>
>> SF.hs:11:10: `>>>' is not a (visible) method of class `Arrow'
>> Failed, modules loaded: none.
>
> import Prelude hiding ((.),id)
> import Control.Category
> you'll also need to define `instance Category SF`, since that is a
> requirement for Arrows.
>
>
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