Re: [Haskell-cafe] Data types and field labels and Show

2007-09-27 Thread Brandon S. Allbery KF8NH 


On Sep 27, 2007, at 14:14 , bbrown wrote:


instance Show SimplePlayer where
show a = Simple posX [ ++ show a{posX} ++ ]


instance Show SimplePlayer where
  show a = Simple posX [ ++ show (posX a) ++ ]

You might also want to consider deriving(Show).

--
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED]
system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED]
electrical and computer engineering, carnegie mellon universityKF8NH


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Re: [Haskell-cafe] Data types and field labels and Show

2007-09-27 Thread Don Stewart 
bbrown:
 I am trying to print the data from a data type and also get the field 
 values.  How would I reference those values if I am declaring a Show function.
 
 I should probably use a class for this, but so far it is working.
 
 I have something along the lines of this.
 
 data SimplePlayer = SimplePlayer { 
   shape :: MechShape,
   angle :: GLfloat,
   posX :: GLfloat,
   posY :: GLfloat
 }
 
 and then to use Show, I was declaring this.
 
 instance Show SimplePlayer where
   show a = Simple posX [ ++ show a{posX} ++ ]
 
 Of course, this didn't compile.
 
 How should I change this code to get the field label values of the type.
 
 Tests/GLTests.hs:20:42: parse error on input `}'

Just derive Show. Types with records will be printed with their labels.
You can then also derive Read, and get serialisation for free.

data SimplePlayer = SimplePlayer
{ shape :: MechShape
, angle :: GLfloat
, posX  :: GLfloat
, posY  :: GLfloat }

   deriving (Read,Show)

*M show $ SimplePlayer square pi 1.0 (exp 1)

SimplePlayer {shape = \square\
  , angle = 3.1415927
  , posX = 1.0
  , posY = 2.7182817}
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Re: [Haskell-cafe] Data types and field labels and Show

2007-09-27 Thread bbrown 
On Thu, 27 Sep 2007 11:41:00 -0700, Don Stewart wrote
 bbrown:
  I am trying to print the data from a data type and also get the field 
  values.  How would I reference those values if I am declaring a Show 
function.
  
  I should probably use a class for this, but so far it is working.
  
  I have something along the lines of this.
  
  data SimplePlayer = SimplePlayer { 
shape :: MechShape,
angle :: GLfloat,
posX :: GLfloat,
posY :: GLfloat
  }
  
  and then to use Show, I was declaring this.
  
  instance Show SimplePlayer where
  show a = Simple posX [ ++ show a{posX} ++ ]
  
  Of course, this didn't compile.
  
  How should I change this code to get the field label values of the type.
  
  Tests/GLTests.hs:20:42: parse error on input `}'
 
 Just derive Show. Types with records will be printed with their labels.
 You can then also derive Read, and get serialisation for free.
 
 data SimplePlayer = SimplePlayer
 { shape :: MechShape
 , angle :: GLfloat
 , posX  :: GLfloat
 , posY  :: GLfloat }
 
deriving (Read,Show)
 
 *M show $ SimplePlayer square pi 1.0 (exp 1)
 
 SimplePlayer {shape = \square\
   , angle = 3.1415927
   , posX = 1.0
   , posY = 2.7182817}

I did this too:

instance Show SimplePlayer where
show simpleEntity = Simple posX [ ++ show (posX simpleEntity) ++ 
] posY [ ++ show (posY 
simpleEntity) ++ ]


--
Berlin Brown
[berlin dot brown at gmail dot com]
http://botspiritcompany.com/botlist/?

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