AI Snips
Chapters
Transcript
Episode notes
Email Server As A Composable Function
- MailCore treated an email server as a pure function mapping an incoming message to zero or more outputs, letting OCaml's function composition express routing and transforms cleanly.
- Replacing a bespoke macro-laden config language with OCaml made configuration composable, testable, and familiar to existing engineers.
Use Your Main Language For Config Generation
- Avoid config-generation into a brittle DSL unless the target provides simple, stable primitives; instead use your team's main programming language for dynamic behavior.
- They chose OCaml because existing tooling and expertise made runtime dynamism and refactorability practical.
Shadowing Old Server To Diff Behavior
- They ran MailCore in shadow mode: every incoming message was forked to the new OCaml server while the old server continued handling live mail, and outputs were streamed and diffed.
- This exposed subtle mismatches and revealed several cases where the legacy server behaved incorrectly.