GoKawiilNew Syl language adds modal type system for compile-time dependent types
A developer is building Syl, a programming language that encodes compile-time computation using a modal type system with two mode axes: staticity (static vs dynamic) and erasure (erased vs unerased). The project's compiler is available on GitHub, and its design draws on András Kovács' two-level type theory research and plans for OxCaml.
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Existing systems languages like C++, Rust, Zig and C already offer some form of compile-time computation through templates, const generics, comptime, or _Generic, but the author argues these features are often restricted or lack a rigorous type system. Syl's approach suggests an attempt to formalize compile-time versus runtime value distinctions more rigorously, which could influence how future languages handle staged computation if the design proves practical. Its reliance on academic type theory work indicates it is currently an experimental, research-oriented project rather than a production-ready tool.
- Syl is an in-development language using a modal type system to handle compile-time dependent types.
- It defines two mode axes—staticity and erasure—governing whether values are known at compile time or runtime.
- The project draws on two-level type theory research and OxCaml's mode system, with its compiler hosted on GitHub.
Source: thenumb.at — Max Slater, 2026-10-26
Published there as: “Compile-Time Dependent Types”
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