Retrie is a tool for codemodding Haskell. Key goals include: Speed: Efficiently rewrite in large (>1 million line) codebases. Safety: Avoids large classes of codemod-related errors. Ease-of-use: Haskell syntax instead of regular expressions. No hand-rolled AST traversals. This package provides a command-line tool (retrie) and a library (Retrie) for making equational edits to Haskell code. Please see the README for examples and usage.