Scale By The Bay 2018 Unconference: Greg Pfeil
summary
Dhall is a total, non-Turing-complete configuration language that still expresses functor, monad and category abstractions, implements kind polymorphism and encodes recursion with the Dada recursion schemes library so recursion remains total. Teams at Formation use a Dhall Kubernetes library to generate real kube YAML with parameterized defaults. The implementation demonstrates rank‑n types to emulate existentials, fast prototyping of compiler features, and practical, working configs though some advanced libraries remain experimental.
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chapters (13)
- 0:00Introduction to Dahl
- 1:00Dahl as a configuration language
- 2:27Dahl syntax and types
- 7:00Pattern matching in Dahl
- 8:25Exploring dal-bhat library
- 13:33Kind polymorphism in Dahl
- 17:51Categories and functors
- 22:10Monoidal categories and monads
- 27:11Existential types and rank-N types
- 29:21Recursion schemes with Dada
- 32:32Dahl in Kubernetes configs
- 35:21Why Dahl is restrictive yet powerful
- 36:44Q&A and closing remarks
