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Haskell Code Refactoring Tool

1 post · Jul 2020

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Meta has developed and open-sourced Retrie, a code refactoring tool for Haskell that simplifies and enhances the process of codemodding large codebases. Retrie allows developers to express rewrites as Haskell equations, offering a balance between the power of AST manipulation and the speed of string replacement. It preserves local scoping, whitespace, and comments, while efficiently narrowing the search space before parsing. This tool has been instrumental in migrating and updating large Haskell codebases like the Sigma anti-abuse rule engine.

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  1. Retrie: Haskell refactoring made easyThis post introduces Retrie, a new open-source Haskell code refactoring tool. It enables codemodding through Haskell syntax equations, offering a middle ground between regex and AST manipulation. Key features include support for expressions, types, and patterns; scripting with side conditions; and preservation of local scoping, whitespace, and comments. An example demonstrates refactoring `map f (map g xs)` to `map (f . g) xs`.