On Wed, Dec 19, 2012 at 8:08 AM, Tom Hawkins <tomahawk...@gmail.com> wrote:
> A few folks have asked me about building EDSLs in Haskell for assembly > programming, so I've posted an example of the approach we have had success > using at BAE Systems. > > It's a bit rough, so if anyone's motivated to polish it up, by all means. > > https://github.com/tomahawkins/asm-dsl-example/ > Thanks. It was nice to read. I was reminded of "The Monad Reader Issue 6" as it explains how to "tie the knot" when creating labels: http://www.haskell.org/wikiupload/1/14/TMR-Issue6.pdf The Russell uses an assembly language DSL as a motivating example and explains how either Haskell98 or mdo can be used to tie the knot, with mdo giving a nicer implementation. The result allows labels to be defined where they are used instead of requiring the user to instantiate them and then associate them with a place in the program. This provides a nice abstraction for building your assembler macros. For example, in your code we see: \begin{code} testProgram :: Asm () testProgram = do begin <- label loop <- label begin -: do i1 10 20 i2 i3 5 loop -: do i4 goto loop \end{code} The corresponding code using the TMR trick might look like this (I've removed the nested indentation): \begin{code} testProgram :: Asm () testProgram = mdo begin <- label i1 10 20 i2 i3 5 loop <- label i4 goto loop \end{code} Other examples demonstrate that labels can be referenced before the line that creates them due to the way mdo works. Jason
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