Re: [Haskell-cafe] How to pretty print code efficiently
Hi all,
Thanks everyone for the help. The HughesPJ module works well for me.
Cheers,
-John
On Mon, Jul 6, 2009 at 3:49 AM, Chris Eidhof wrote:
> On 4 jul 2009, at 05:13, Alexander Dunlap wrote:
>
> On Fri, Jul 3, 2009 at 6:45 PM, John Ky wrote:
>>
>>> Hi,
>>>
>>> Currently I'm pretty printing code by building arrays of strings and
>>> calling
>>> indent. For example:
>>>
>>> instance JavaPrintableNamed AST.EnumeratedType where
>>> javaLinesNamed parentName (AST.EnumeratedType memberDefinitions) =
>>> [ "public enum " ++ asJavaId(parentName)
>>> , "{"
>>> ] ++ memberCodeLines ++
>>> [ "}"
>>> , ""
>>> ]
>>> where
>>> memberCodeLines = indent $ javaLines memberDefinitions
>>>
>>> The indent function takes a list of strings and adds an indent to the
>>> beginning of every line.
>>>
>>> I can imagine this to be very inefficient as it builds many strings and
>>> concatenates them.
>>>
>>> In Ruby, I might do the same thing like this:
>>>
>>> class EnumeratedType < JavaPrintableNamed
>>> def writeTo(writer)
>>> writer.print "public enum "
>>> writer.puts self.asJavaId
>>> writer.puts "{"
>>> writer.indent do
>>> self.memberDefinitions.writeTo(writer)
>>> writer.puts
>>> end
>>>
>>> where above, the writer.indent takes care of the indent, and everything
>>> is
>>> appended to a stream, which doesn't seem so bad in terms of efficiency.
>>>
>>> I'm looking for a way to do something similar in Haskell.
>>>
>>> Anyone can give me a hand?
>>>
>>> Thanks
>>>
>>> -John
>>>
>>>
>>> ___
>>>
>>
>> You may want to investigate the standard module
>> Text.PrettyPrint.HughesPJ, which contains a number of (I assume fairly
>> efficient) combinators for pretty printing.
>>
>
> I second that. Also, there is uulib which has a pretty printing module
> that's quite similar:
>
>
> http://hackage.haskell.org/packages/archive/uulib/0.9.10/doc/html/UU-PPrint.html
>
> I think both packages are based on the paper "The Design of a
> Pretty-printing Library" which can be found at
> http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps
>
> Not only do they provide abstractions for things like indentation,
> concatenation in different forms, etc., but they also are more efficient
> than a naive implementation using lists.
>
> -chris
>
> -chris
>
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Re: [Haskell-cafe] How to pretty print code efficiently
On 4 jul 2009, at 05:13, Alexander Dunlap wrote:
On Fri, Jul 3, 2009 at 6:45 PM, John Ky wrote:
Hi,
Currently I'm pretty printing code by building arrays of strings
and calling
indent. For example:
instance JavaPrintableNamed AST.EnumeratedType where
javaLinesNamed parentName (AST.EnumeratedType memberDefinitions) =
[ "public enum " ++ asJavaId(parentName)
, "{"
] ++ memberCodeLines ++
[ "}"
, ""
]
where
memberCodeLines = indent $ javaLines memberDefinitions
The indent function takes a list of strings and adds an indent to the
beginning of every line.
I can imagine this to be very inefficient as it builds many strings
and
concatenates them.
In Ruby, I might do the same thing like this:
class EnumeratedType < JavaPrintableNamed
def writeTo(writer)
writer.print "public enum "
writer.puts self.asJavaId
writer.puts "{"
writer.indent do
self.memberDefinitions.writeTo(writer)
writer.puts
end
where above, the writer.indent takes care of the indent, and
everything is
appended to a stream, which doesn't seem so bad in terms of
efficiency.
I'm looking for a way to do something similar in Haskell.
Anyone can give me a hand?
Thanks
-John
___
You may want to investigate the standard module
Text.PrettyPrint.HughesPJ, which contains a number of (I assume fairly
efficient) combinators for pretty printing.
I second that. Also, there is uulib which has a pretty printing module
that's quite similar:
http://hackage.haskell.org/packages/archive/uulib/0.9.10/doc/html/UU-PPrint.html
I think both packages are based on the paper "The Design of a Pretty-
printing Library" which can be found at http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps
Not only do they provide abstractions for things like indentation,
concatenation in different forms, etc., but they also are more
efficient than a naive implementation using lists.
-chris
-chris
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Re: [Haskell-cafe] How to pretty print code efficiently
On Fri, Jul 3, 2009 at 6:45 PM, John Ky wrote:
> Hi,
>
> Currently I'm pretty printing code by building arrays of strings and calling
> indent. For example:
>
> instance JavaPrintableNamed AST.EnumeratedType where
> javaLinesNamed parentName (AST.EnumeratedType memberDefinitions) =
> [ "public enum " ++ asJavaId(parentName)
> , "{"
> ] ++ memberCodeLines ++
> [ "}"
> , ""
> ]
> where
> memberCodeLines = indent $ javaLines memberDefinitions
>
> The indent function takes a list of strings and adds an indent to the
> beginning of every line.
>
> I can imagine this to be very inefficient as it builds many strings and
> concatenates them.
>
> In Ruby, I might do the same thing like this:
>
> class EnumeratedType < JavaPrintableNamed
> def writeTo(writer)
> writer.print "public enum "
> writer.puts self.asJavaId
> writer.puts "{"
> writer.indent do
> self.memberDefinitions.writeTo(writer)
> writer.puts
> end
>
> where above, the writer.indent takes care of the indent, and everything is
> appended to a stream, which doesn't seem so bad in terms of efficiency.
>
> I'm looking for a way to do something similar in Haskell.
>
> Anyone can give me a hand?
>
> Thanks
>
> -John
>
>
> ___
You may want to investigate the standard module
Text.PrettyPrint.HughesPJ, which contains a number of (I assume fairly
efficient) combinators for pretty printing.
Alex
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