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Zero-Cost 'Tagless Final' in Rust with GADT-style Enums

The article explores implementing the 'Tagless Initial' variant of the Tagless Final pattern in Rust using GADT-style enums, demonstrating that complex functional programming abstractions like embedded DSLs can compile down to zero-cost assembly. The author walks through translating Haskell-style GADT expressions into Rust, showing the compiler can completely erase type-level abstractions at compile time.

Background

Tagless Final is a well-known pattern in functional programming for encoding algebraic effects and DSLs without tag dispatch overhead. While popular in Haskell and Scala, adapting it to Rust's type system presents unique challenges due to Rust's lack of native GADT support.

Source
Lobsters
Published
Aug 28, 2026 at 06:51 PM
Score
6.0 / 10