So, if I understand this:
Parsec is a DSL, I'm going to venture it's a "Deep embedding" -- I
don't understand the internals, but if I were to build something like
Parsec, I would probably build up a "Parser" datastructure and then
apply optimizations to it, then "run" it with another function.
Am I on the right track here?
/Joe
On Oct 7, 2009, at 11:24 AM, Emil Axelsson wrote:
Hi,
A DSL is just a domain-specific language. It doesn't imply any
specific implementation technique.
An *embedded* DSL is a library implemented in a more general
language, which has been designed to give the "feeling" of a stand-
alone language. Still nothing about implementation.
A *shallow embedding* of a DSL is when the "evaluation" is done
immediately by the functions and combinators of the DSL. I don't
think it's possible to draw a line between a combinator library and
a shallowly embedded DSL.
A *deep embedding* is when interpretation is done on an intermediate
data structure.
/ Emil
Günther Schmidt skrev:
Hi all,
for people that have followed my posts on the DSL subject this
question probably will seem strange, especially asking it now.
I have read quite a lot lately on the subject, most of it written
by the great old ones, (come on guys you know whom I mean :)).
What I could gather from their papers was, that a DSL is basically
something entirely abstract as such, ie. it allows you build and
combine expressions in a language which is specific for your
problem domain.
Irregardless of further details on how to do that, and there are
quite a few, the crux as such is that they are abstract of "meaning".
The meaning depends how you *evaluate* the expression, which can be
in more than merely one way, which is where, as far as I understand
it, the true power lies.
So, you might wonder, since I figured it out this far, why ask what
a DSL is?
Because out there I see quite a lot of stuff that is labeled as
DSL, I mean for example packages on hackage, quite useuful ones
too, where I don't see the split of assembling an expression tree
from evaluating it, to me that seems more like combinator libraries.
Thus:
What is a DSL?
Günther
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
