Fuse
statically typed functional programming language
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Hi HN! I've been working on the fuse programming language, it's a statically typed purely functional language with higher-kinder types and ad-hoc polymorphism. It compiles to the GRIN whole-program optimizer, producing LLVM-generated native code.Fuse supports ADTs, Generics, Type Methods, Traits, Pattern matching etc. all in a functional style with no mutations.I’ve been developing the language for 5 years, with code written in Scala. I’ve started coding the language from the base of System F that was implemented as part of the book: Types and Programming Languages (tapl). And then extending with concepts such as Bidirectional Type Checking with Higher-Rank Polymorphism.I’ve mainly drawn inspiration from Rust, Haskell, Scala and Python (in terms of syntax). It all started because I wanted a language that has Rust-like concepts such as: ADT, Traits, Impl block syntax, etc. but have the pure functional semantics.I'd would love feedback on the language design and its general usage.
HN · launched Aug 2, 2026 · 121 upvotes (top 6%) · 0 views
Niche: programming languages and interpreters · 161 launches, 2 in the last 7 days ▼ -75% · Explore this niche →
Category and tags
- Horizontal
- Dev tools
- Developer
- Not AI
- Hobby / open-source project
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More like this: all 161 launches in programming languages and interpreters →
Could you build this?
No Designing and implementing a statically typed functional programming language with higher-kinded types, System F type checking, bidirectional inference, and compilation via GRIN to LLVM requires deep expertise in compiler theory and type systems.
What it would actually take: Building Fuse requires implementing an AST, lexer/parser, and bidirectional type checker supporting higher-kinded types and traits, then compiling to GRIN (Graph Reduction Intermediate Notation) for functional program optimization, and lowering to LLVM IR. The stack typically involves Haskell, OCaml, or Rust with LLVM bindings. Deep theoretical understanding of type theory, lambda calculus optimizations, and low-level code generation is required.
Discussion
20 comments analyzed.
Competitors mentioned: Haskell, Rust, Dart, Luau, Elm
Concerns raised: No FFI support yet, Type system limitations with Self and higher-kinded types, Functional languages notoriously slower than imperative due to lack of mutations, Supercompilation compilation resources grow superlinearly, Unclear how type system scales in practice
Feature requests: User-defined operators, Lazy evaluation instead of strict evaluation, Support for higher-kinded types without losing expressiveness, FFI support, Equivalence of terms for program verification
Competitors
Other products that read as similar to this one : 205 launches clear the similarity bar, closest 8 shown.
Attention rank: #10 of 206 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 274 days after the earliest competitor.
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