arXiv:1312.0658cs.PL
A Theory of Changes for Higher-Order Languages - Incrementalizing λ-Calculi by Static Differentiation
Abstract
If the result of an expensive computation is invalidated by a small change to the input, the old result should be updated incrementally instead of reexecuting the whole computation. We incrementalize programs through their derivative. A derivative maps changes in the program's input directly to changes in the program's output, without reexecuting the original program. We present a program transformation taking programs to their derivatives, which is fully static and automatic, supports first-class functions, and produces derivatives amenable to standard optimization. We prove the program transformation correct in Agda for a family of simply-typed λ-calculi, parameterized by base types and primitives. A precise interface specifies what is required to incrementalize the chosen primitives. We investigate performance by a case study: We implement in Scala the program transformation, a plugin and improve performance of a nontrivial program by orders of magnitude.
I think this is an area where practice has lagged quite far behind theory (for entirely reasonable practical reasons). I've seen quite a few papers relating to incremental parsing, compilation, etc. (e.g. [1,2]) but afaik very few build systems actually take advantage. [1]…
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