A Field Guide to DSL Design
summary
Summarizes practical rules and a working example DSL for data assertions in Scala: builds an imperative, eagerly evaluated mini-language that uses infix/dot syntax, implicit classes to add a should/should be API, contravariant Predicate[T] types, and a sealed trait predicate hierarchy to separate modal vs compound predicates. Covers concrete workarounds—parentheses for chaining, an overload to handle null, implicit lifts for true/false, and adding negative failure messages for negation—and links to GitHub with the actual code that compiles and runs.
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chapters (7)
- 0:00Start
- 5:54Examples
- 15:19Mode
- 23:21Implicit Classes
- 25:10Foundation
- 31:32Parameterization
- 37:21Negation
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