MuniHac 2018: Keynote: The Curious Case of Pattern-Match Coverage Checking

Ryan Scott explores the design considerations and challenges of pattern-match coverage checking and exhaustiveness analysis in GHC.

Title: The Curious Case of Pattern-Match Coverage Checking Speaker: Ryan Scott Abstract: Patterns in Haskell are useful, but they're prone to issues such as incomplete and redundant patterns if used carelessly. Thankfully, GHC offers a very handy static analysis, called pattern-match coverage checking, which emits warnings if you use patterns recklessly. This talk explores the design considerations of coverage checking, considers some of the more challenging aspects of determining whether patterns are exhaustive, and even demonstrates some patterns that aren't checked correctly (as of GHC 8.6!) but will be soon. Recorded at MuniHac 2018 / munihac.github.io by Maximilian Huber / TNG Technology Consulting GmbH