Re: [Haskell-cafe] Advice needed on how to improve some code

16 Apr 2015


      Thanks Tom, David and Claude for your replies.
...
On 16 Apr 2015, at 4:03 pm, Tom Ellis  wrote:
The first thing you should do is define
parseDeviceGPSDataOf constructor parser setField =
      ( \pl' -> let pld = P.payloadData pl' in
                 if testBit mdm ( fromEnum constructor )
                   then
                     parser >>=
                     ( \s -> return ( pl' { P.payloadData = setField pld (Just s) } } ) )
                   else
                     return pl' )
and your chain of binds will become
setgpsData pld = pld { P.gpsData = Just s }
   ...
parseDeviceDataOf D.GPS parseDeviceGPSData setgpsData >>=
   parseDeviceDataOf D.GSM parseDeviceDSMData setgsmData >>=
   parseDeviceDataOf D.COT parseDeviceCOTData setcotData >>=
   ...
Then I would probably write
deviceSpecs = [ (D.GPS, parseDeviceGPSData, setgpsData)
                 , (D.GSM, parseDeviceDSMData, setgsmData)
                 , (D.COT, parseDeviceCOTData, setcotData) ]
and turn the chain of binds into a fold.
I’ll do as you have suggested Tom.  Thanks.

Jeff