You probably don't need recursion in the DSL for this (that would require a way to detect cycles in the expressions). For this example, it looks like all you need is to add something like `map` as a DSL construct.

Your example could perhaps be expressed as

  forEach (1,1000) (\n -> out (matrixMult, A, n, row, matrix-row))

For this you need a way to reify functions in the DSL. For an example of how to do this, see the `While` and `Arr` constructs in this paper:

  http://www.cse.chalmers.se/~emax/documents/svenningsson2013combining.pdf

I'm not familiar with your particular DSL though, so I might have missed something.

/ Emil

2013-02-17 23:53, fritsch <at> joerg.cc skrev:

I have a tiny DSL that actually works quite well. When I say

import language.CWMWL

main = runCWMWL $ do
     out (matrixMult, A, 1, row, matrix-row)

then runCWMWL is a function that is exported by language.CWMWL. This parses the experession and takes some action.

Now, A is the name of the matrix and the third tuple element would represent the numbe of the row. For example 1 to 10000. I want to achieve some sort of "elegant" (means readable code, a good representation) recursion that would let me do something like
    sequence [ out (matrixMult, A, n, row, matrix-row) | n <- [1..1000] ]
but in a nicer manner an without expending this to 10000 lines of code at compile time.

How can I best introduce recursion into my DSL or borrow this from the host language Haskell "effectively"?

--Joerg



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