Software Unscripted Gleam's Design and Compiler - with creator Louis Pilfold
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Jan 10, 2026 Louis Pilfold, the creator of the Gleam programming language, shares his insights on its unique design choices, like substituting traditional if statements with pattern-matching case expressions. He discusses the influences of Erlang and Elixir, and why Gleam avoids currying for better compatibility. Louis also explains the practicalities of developing a typechecker and his approach to module caching for fast builds. Additionally, he highlights the challenges of integrating a JavaScript backend and the future of community-driven solutions.
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Pattern Matching Replaces If
- Gleam intentionally omits an if construct and uses pattern-matching case for all conditional logic.
- Louis found developers adapted quickly and the design simplified language surface area.
Erlang's Guard Limits Sparked Change
- Louis described Erlang's limited if as a trigger for preferring case and eventually removing if from Gleam.
- Repeated Erlang usage convinced him one conditional form was sufficient.
No Currying For BEAM Interop
- Gleam avoids currying because the BEAM and existing Erlang/Elixir ecosystems don't support it well.
- Louis prioritized interop with the BEAM over Haskell-style currying ergonomics.