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The Disciplined Disciple Compiler (DDC)

Disciple is a dialect of Haskell that uses strict evaluation as the default and supports destructive update of arbitrary data structures. Disciple includes region, effect and closure typing, and this extra information provides a handle on the operational behaviour of code that isn't available in other languages. Programs can be written in either a pure/functional or effectful/imperative style, and one of our goals is to provide both styles coherently in the same language. The two styles can be mixed safely, for example: when using laziness the type system guarantees that computations with visible side effects are not suspended. Many Haskell programs are also Disciple programs, or will run with minor changes. Our target applications are the ones that you always find yourself writing C programs for, because existing functional languages are too slow, use too much memory, or don't let you update the data that you need to.

DDC is still in the "research prototype" stage, meaning that it will compile programs if you are nice to it, but expect compiler panics and missing features. You'll get panics due to ungraceful handling of errors in the source code, but valid programs should compile ok. Here are some working examples, along with their Disciple source code:

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State of Play

This section records what the DDC developers are actively working on. If you're hacking on something DDC related then by all means add yourself here. Records are dropped off if they're older than about a month.

Ben Lippmeier (benl23) -- updated 25th May 2011

  • I'm still working on mechanising the proofs of the DDC core language in Coq.
  • I've finished Progress, Preservation and Big<>Small step semantics for Simply Typed Lambda Calculus (STLC), System-F, System-F2 and PCF.
  • The Coq proofs are in the main DDC tree at
  • I'm now working on STLC extended with data types and case expressions.
  • The next hurdle seems to be managing the mutual recursion between the exp and alternative types, as it appears I need to generate my own induction principles.
  • I'm now following an existing proof of the soundness of the STG machine, which is a similar simple functional language.

Erik de Castro Lopo (m3ga) -- updated 16th Apr 2011

  • The LLVM backend is basically done and is already showing improved runtime performance compared with the C backend.
  • Make sure the LLVM backend works with llvm 2.8 and 2.9 (have been using 2.7 until now).
  • Make sure the LLVM backend works for linux-powerpc32, darwin-x86 and darwin-x86_64.
  • Plan to examine all the currently open bugs to see if any can be easily fixed and closed.
  • Improvements to DDC's library.



Fully supported: OSX/x86, Linux/x86, Linux/x86_64, Linux/PPC, FreeBSD/x86
Partially supported: Cygwin/x86?


How you can help

  • Download the compiler, write programs, and file bug reports!
  • Write more tests. Cute graphical demos are especially fun.
  • Fix bugs! The ones on the newbie list should be easy to get started on, otherwise we're pushing for the 0.1.3 release
  • 'port across GHC base libraries like Data.Either and Data.Map.

How to get help

Further Reading

Related Work

Another bibliography by Jianzhou Zhao


  • Eff. Bauer, Pretnar. (active)
  • BitC. A functional language with first class mutability. Shapiro, Sridhar, Doerrie. (active)
  • Timber A real-time Haskell like language. Nordlander et al. (active)
  • Cyclone A type safe dialect of C using region typing. Grossman, Hicks, Jim, Morrisett, Swamy, Wang et al. (active)
  • MLKit A ML compiler using region typing. Elsman, Hallenberg, Varming, Tofte, Birkedal et al. (active)
  • FX The original effect typing system. Gifford, Jouvelot et al. (inactive)

Recent Papers

If you know of other recent work on effects, region typing, controlling mutability, or capability calculi then please add it here. We are particularly interested in systems that can express the noninterference of concurrent threads in their type systems, while not requiring all data to be constant (as in Haskell), and not adding intermediate messaging protocols (as in Erlang or with STM).

Key Papers