[Haskell-cafe] EDSL's using Filet-O-Fish of Barrelfish project

Pierre-Evariste Dagand pedagand at gmail.com
Sun Feb 14 12:57:16 EST 2010


On Sun, Feb 14, 2010 at 4:44 PM, C K Kashyap <ckkashyap at gmail.com> wrote:
> For example, lets say, I wanted to write a EDSL for Linux's network drivers. Could I use
> Filet-O-Fish and generate a EDSL that allows me to write a driver in a
> really highlevel manner and then generate the "C" code for it?

That sounds perfectly reasonable to me.

However, you write "generate a EDSL that allows me to [...]".
Filet-o-Fish will not "generate" an EDSL for you. Filet-o-Fish will
help you implement the *back-end* of your (E)DSL compiler. You still
have to define a syntax and a semantics for your (E)DSL. FoF is here
to bridge the gap from your (E)DSL semantics to C, by doing it for

In Barrelfish, we have implemented the capability system this way: we
have defined the syntax and semantics of a DSL for specifying
capability systems, called Hamlet. Then, the Hamlet compiler back-end
has been implemented with FoF, which allowed us, for example, to
quickcheck some key property of the generated C code, by working at
the (more friendly) FoF code level (assuming that FoF is "correct"

For fun, we have implemented tic-tac-toe in the capability system.
Each game state is represented by a capability, you can "retype" a
capability from one to another iif this is a valid tic-tac-toe move.
For a 3x3 board, that's more than 4.800 unique capabilities, which is
quite a huge number of caps for an OS :-) You won't find that code in
the official Barrelfish, though.

Whereas this work was done in the specific context of Barrelfish,
other people have designed DSLs for Linux. The examples I have in
mind, related to your question are:
  * Devil [http://phoenix.inria.fr/index.php/projects/past-projects/devil]:
a device interface language, but still quite low-level compared to
what you're interested in ;
  * Bossa [http://bossa.lip6.fr/]: a DSL for specifying schedulers for
Linux, which automatically turns the spec into code directly
integrated in the Linux kernel.

I had the opportunity to discuss with the designer of these systems
and it is clear to me that this could be done with FoF as well.

Hope this help,

Pierre-Evariste DAGAND

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