Let me add to this, as I've used the term "DSL" without (*gasp*) fully understanding it before. In addition to "What is a DSL", I'd like to ask: "How is a DSL different from an API?" -- in the sense that an API is a set of, say, combinators to filter email + a monad in which to combine them. Or even the API in the more traditional sense of the set of exposed operations on a given type. Is an API a kind of DSL? A kind of Embedded DSL? Also, "What is the difference between an EDSL and a DSL?" -- I've got a vague intuition of the difference, but am unsure how to particularly delineate them. Also, any good introductory papers/books/other resources on DSLs and how to design, build and use them would be _lovely_. /Joe On Oct 7, 2009, at 11:10 AM, Günther Schmidt wrote:
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
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