Express: applications of dynamically typed Haskell expressions
summary
The express library implements dynamically typed Haskell expressions as a wrapper around Data.Dynamic and adds pretty printing, delayed evaluation, support for variables and expression matching. It deep-encodes values as constructor applications and exposes candidate generation up to size 5 and testing (60 random tests by default). Concrete results: an equation conjecturer finds associativity/append laws in <1s; a counterexample generalizer produces patterned counterexamples; a brute-force synthesizer is implemented in ~66 lines but does not scale; refactoring two tools cuts their code by ~25%.
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chapters (10)
- 0:00Introduction
- 1:05What is Express
- 2:08Express library
- 3:10GHCI
- 4:50Heterogeneous lists
- 6:30Encoding variables
- 7:26Contradictory equations
- 13:07Deep encoding
- 14:46Generalizing counter examples
- 18:45Synthesising functions
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