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About mypy

Jukka Lehtosalo began work on mypy in 2012. The project borrows heavily from Jukka's earlier work on Alore, a Python-inspired language with an optional static type system. Other than by providing Python syntax and libraries, mypy also differs from Alore by striving for runtime type safety whenever practical.

In addition to Python and Alore, the design of mypy has been influenced by Java, C#, Typed Racket, Boo, Dart and the work of Jeremy G. Siek and Walid Taha on gradual typing.

Mypy Team

Jukka Lehtosalo

Jukka is the primary developer of mypy. Born and raised in Finland, Jukka is currently working on mypy at the University of Cambridge Computer Laboratory in the UK as a PhD student. Before Cambridge, Jukka worked as software engineer and later as development manager for 9 years.

Jukka lives with his wife, two children, a cat and a dog in a village near Cambridge.


The following people have contributed to the development of mypy (in alphabetical order):

See also the full CREDITS.

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Contact Jukka at to join the team!


The development of mypy and the research behind mypy has been supported financially by the Finnish Cultural Foundation, the Academy of Finland, Emil Aaltonen Foundation, Engineering and Physical Sciences Research Council UK, University of Cambridge Computer Laboratory and ACM.