target language grammars.

Hello all,


> Can anyone point to applications where the target language
> grammar is made use of?


What about an interactive compiler construction environment where you
define a context-free source language, a context-free target language,
and a set of (functional-style) rewrite rules to rewrite input syntax
to output syntax (with the rewrite rules using both the input and the
output syntax)?


The language that does this is called ASF+SDF, and the implementation
of it is called Meta. You can find it (with many publications) at
http://www.cwi.nl/htbin/sen1/twiki/bin/view/SEN1/MetaEnvironment


I have been using it for almost 2 years now for writing my compiler.
At first having everything based on grammars feels weird, but now I
wouldn't want to go back to the 'old' way with eg lex/yacc.


> Perhaps, in translating a program, we could generate a representation
> of the program as a parse tree in the target language and then


No need to do anything yourselves, Meta does it all for you.




> Mostly here I am thinking of cases where the target language is
> something like postscript, pdf, or latex. (The Lyx program translates
> Lyx files to latex files.)


Since the grammar is context-free, you get context-free output, for
example without proper indentation.
The grammar simply does not contain this layout-information, so it
cannot do layouting of the output.


On the other hand, since the output is available in a tree, you can
quite easily write a formatter if you want.


> I am particularly interested in the case that a target language
> program represents how some data is to be displayed on a computer


If you have a context-free grammar, Meta can give you the output in
tree-format.


Albert

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