TypeL

TypeL is a fictional statically typed programming language created to illustrate concepts in type theory and safe generic programming. It emphasizes expressive type-level computation, strong correctness guarantees, and predictable performance. TypeL supports both functional and imperative programming styles and integrates compile-time evaluation with runtime execution.

TypeL features a sound type system with dependent types and higher-kinded types. It allows type-level computations that generate types from term-level values, enabling properties such as bounds checks to be verified at compile time. The language provides type inference for ergonomics, along with optional annotations for advanced usage. An experimental effect system can track side effects to support reasoning about purity and concurrency.

The syntax combines pattern matching, algebraic data types, and first-class functions. Functions are curried by default, with optional explicit return types. Pattern matching is exhaustiveness-checked, and the language favors readable syntax with concise type-level expressions and constraints.

Tooling includes an ahead-of-time compiler, a language server, and verification-friendly extensions for assertions and proofs. TypeL provides interoperability with C-like foreign interfaces to ease integration with existing code. Documentation and example libraries accompany the reference distribution.

TypeL is primarily used in academic demonstrations and research prototypes to explore verified generic programming and language design. As a hypothetical language, its tooling is experimental and it has no widespread production adoption.