gleam

Type-driven design in Gleam starts by defining domain types that make illegal states unrepresentable, then implementing functions that respect those types. Build your domain model first, write tests that verify type safety and error handling, then implement to pass. This approach catches bugs at compile time and ensures strict type guarantees throughout your codebase.

Yes, TDD works well with Gleam. Write a failing test first, then implement code to pass it. Gleam's strong type system integrates naturally with TDD: your tests define expected types and behavior, and the compiler enforces correctness before runtime. This cycle ensures safe error propagation and idiomatic patterns.

Gleam enforces explicit error propagation through its type system. Use Result and Option types to represent success and failure cases, making error handling unambiguous. Pipeline-based refactoring keeps error paths visible and manageable, preventing silent failures and ensuring all error cases are handled at compile time.

Structure Gleam projects using idiomatic functional patterns that align with BEAM's actor model and message-passing concurrency. Use gleam.toml to configure dependencies, organize code into focused modules, and leverage Erlang interop when needed. Type-driven design ensures your pipelines integrate safely with the BEAM runtime.

Yes, Gleam runs on the BEAM virtual machine and interoperates with Erlang. You can call Erlang functions from Gleam and vice versa. However, Gleam's type system wraps external calls, so you define types that match Erlang's behavior and ensure safe error handling at the boundary.