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Fun of writing Unison
Yoshikuni Kato
FP AMS, 10.09.2025
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Unison
• Unison is a friendly programming
language from the future:
statically-typed, functional, and a lot
of fun1
• ML-like syntax
• Implemented in functional stack:
Haskell, Elm
• Have you used Unison before?
1 https://www.unison-lang.org/
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My libraries
• @yoching/units - Unit conversion and calculation
• @yoching/codable - Ergonomic data decoding and encoding
• With Abilities
Both on Unison Share.
I will share how I write Unison with demo.
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Unison Characteristics
• Content-addressed & Unison Codebase Manager
• Abilities: Algebraic Effects
• Distributed computing & Unison Cloud
• Unison Share: GitHub for Unison
• Computable documentation
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Content-addressed & UCM
• functions/terms/types are referenced by hash of the
Abstruct Syntax Tree. Names are aliases to the hash
• Code is stored in a database as serialized AST with its hash
(=“codebase”)
• Tool to access the codebase = Unison Codebase Manager
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Live Demo
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Unison experience
• Updating codebase is safe, easy, and quick
• Substitutes a lot of work IDEs currently do
• Future of programming?
• Unison is a friendly programming language from the
future
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Tips
• Get used to the tooling first. Ability (algebraic effects) next
• There is Dutch Unison Meetup
• Check #meetups of Unison Discord
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Yoshikuni Kato
• Software engineer since 2013,
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, University of Tokyo alumni
• Now freelancing
• TS/Swift/Python for client projects,
Elm/Unison for OSS
• Organizing Amsterdam Casual FP
meetup - unconference style
• Open to new projects soon (maybe
FP?)
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