2010/JIT-Compiling Domain Specific Languages

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During this talk, we will survey real-world implementations of JIT-compiled embedded DSLs and their applications.

Speaker: Jeremy Voorhis

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Contributed notes

Domain-Specific Languages (DSLs) as jargon for shared use by domain experts, programmers. c.f. Landin's "The Next 700 Programming Languages," where he creates a "you know what I mean" meta-DSL.

In a DSL, your model should represent domain concepts. You should use the language of the experts.

Interpreted DSLs are easy to build / maintain. Good choice "in the absence of performance requirements," he says cheekily.  ;-)

Compiled DSLs have an initial overhead. But they can generate code in another target language, or even (through JIT) machine code.

External vs. embedded DSL: is your DSL a language or a library?

Examples: 3 musical DSLs

  • Csound: list of musical events in a score
  • ChucK: more programming-like
  • Faust: wire up DSP steps in a graphical block diagram

Using LLVM

  • Suite of compiler backend tools
  • Generate intermediate representation (IR)
    • Uses single-assignment style, types, modules, metadata
    • Think of it as a target-independent, type-safe assembly language
  • Transform IR and generate machine code
  • Backends for many languages
    • Ruby example that builds up the IR in a Builder-like syntax
    • I put a DSL in your DSL, so you can ...

Introducing Siren

  • JITtable music DSL
  • Can process audio in realtime

Q. "How would you slur notes?" A. "Maybe I'll have an answer for that, but not today."

Modeling sound

  • Sound as function from Time (Real) to Amplitude (Real)
  • Programmer can create a new kind of sound by defining needed parameters + "render" function to return amplitude at a particular relative time
  • A programming language = lambda calculus + handy constants
  • Siren generates and walks an AST from Ruby code, generating IR through the builder-like syntax
    • c.f. Hutton's "Fold and Unfold for Denotational Semantics"
  • Generates some IR, some C (for easy calls to portaudio)
    • Easy to pass generated code to the runtime
  • Demo of Siren playing Satie's Gymnopaedie

For more, see http://github.com/jvoorhis