dmypy
mypy daemon for fast incremental type checking
TLDR
SYNOPSIS
dmypy command [options] [files...]
DESCRIPTION
dmypy is the daemon interface for mypy, Python's static type checker. It keeps mypy running as a background process, dramatically reducing type checking time by maintaining cached state between runs.The daemon pre-computes and caches type information, making incremental checks nearly instantaneous. This is particularly valuable for large codebases where full mypy runs would be slow.dmypy integrates with editors and CI systems that need fast, repeated type checks. It handles the daemon lifecycle and forwards type checking requests to the running mypy instance.
PARAMETERS
COMMAND
Operation: start, stop, run, status, restart, kill.start
Start the mypy daemon.stop
Stop the daemon gracefully.run [FILES]
Type check files via daemon.status
Show daemon status.restart
Restart the daemon.kill
Forcefully terminate daemon.--status-file FILE
Custom status file location.--help
Display help information.
INSTALL
CAVEATS
Daemon must be restarted after configuration changes. Memory usage increases with project size. May need restart if mypy version changes. Not suitable for parallel type checking.
HISTORY
dmypy was introduced as part of mypy, originally created by Jukka Lehtosalo at Dropbox. The daemon mode was added to address performance concerns with large codebases requiring frequent type checks during development.