Alexis King wrote this piece about his concise, simple way to explain what it means to practice type-driven design. He has now a single, snappy slogan that encapsulates what type-driven design means to him, and better yet, it’s only three words long: Parse, don’t validate.
The article then explains:
- The essence of type-driven design
- Turning partial functions total
- The power of parsing
- The danger of validation
- Parsing, not validating, in practice
Author’s advice is to focus on the datatypes. And follow 2 simple ideas: Use a data structure that makes illegal states unrepresentable and push the burden of proof upward as far as possible, but no further. That said, it is not always easy. Excellent read!
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