I wonder if pattern matching could be less verbose. Maybe this sounds weird,
but here is example of what I mean:
type A = (Int, String)
f :: String - A - A
f s (i,s') = (i, s ++ s')
data B = B Int String deriving Show
g :: String - B - B
g s (B i s') = B i $ s ++ s'
Types A/B and
2010/7/15 Alexey Karakulov ankaraku...@gmail.com:
I wonder if pattern matching could be less verbose. Maybe this sounds weird,
but here is example of what I mean:
type A = (Int, String)
f :: String - A - A
f s (i,s') = (i, s ++ s')
data B = B Int String deriving Show
g :: String - B - B
Generics can help. But they are much slower than pattern matching.
{-# LANGUAGE DeriveDataTypeable #-}
import Data.Generics
import Control.Monad.State
type A = ( Int, String )
data B = B Int String deriving ( Show, Typeable, Data )
f :: ( Typeable a, Data d ) = [ a ] - d - d
f s = changeField
begin Vo Minh Thu quotation:
I guess it is short because you make use of second... so you can
define second' for your B data type, or make B an instance of Arrow.
I don't think that's the case. The code for f is making use of the
Arrow instance for (-):
second :: Arrow a = a b c -
begin Mike Dillon quotation:
begin Vo Minh Thu quotation:
I guess it is short because you make use of second... so you can
define second' for your B data type, or make B an instance of Arrow.
I don't think that's the case. The code for f is making use of the
Arrow instance for (-):
