On Fri, Jul 3, 2009 at 6:45 PM, John Ky
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
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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