A small programming language where everything is pass-by-value
Details
- External ID
- 46759520
- Source
- HN
- Company
- —
- Product
- A small programming language where everything is pass-by-value
- Website domain
- github.com
- Launched
- Jan. 25, 2026
- Cohort
- —
- Upvotes
- 91
- Upvotes percentile
- 0.8899868247694335
- Tags
- —
- Fetched at
- Sept. 7, 2026, 9:25 p.m.
- Updated at
- Sept. 7, 2026, 9:25 p.m.
Description
This is a hobby project of mine that I started a few years ago to learn about programming language implementation. It was created 95% without AI, although a few recent commits include code from Gemini CLI.I started out following Crafting Interpreters, but gradually branched off that until I had almost nothing left in common.Tech stack: Rust, Cranelift (JIT compilation), LALRPOP (parser).Original title: "A small programming language where everything is a value" (edited based on comments)
Enrichment
- Theme
- database infrastructure and developer tools
- Vertical
- Horizontal
- Function
- Dev tools
- Audience
- Developer
- AI stance
- Not AI
- Project type
- Hobby / open-source project
- Normalized one-liner
- programming language with pass-by-value semantics
- Manually corrected
- False
Could you build this?
No Writing a custom programming language compiler or bytecode virtual machine with custom semantics requires specialized theoretical and practical knowledge of compiler design.
What it would actually take: A real implementation involves building a custom lexer, parser (AST generator), semantic analyzer, and either an AST-walking interpreter or a bytecode VM with a custom runtime and garbage collection / memory management that enforces strict pass-by-value semantics across arbitrary data structures. It requires expertise in compiler construction, formal grammar definitions, and low-level runtime systems.
Discussion
20 comments analyzed.
Competitors mentioned: Rust (immutability by default syntax), F# (immutability encouragement), Swift (copy-on-write for containers), Haskell (pure functional approach), APL (value-only semantics)
Concerns raised: Threading state through program is painful without reference semantics, Reference counting overhead with multithreading (atomic refcounts), Performance cost of copy-on-write vs in-place mutation, Difficult to build custom data structures without reference semantics, Parser ambiguity between function calls and loop bodies
Feature requests: Support concurrent mutable containers, Simplify block syntax (either keywords or parens, not both), Use persistent data structures instead of copy-on-write
Competitors
Other products that read as similar to this one — 114 launches clear the similarity bar, closest 8 shown.
Attention rank: #20 of 115 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 85 days after the earliest competitor.
- AttaLambda: a language where types and data are made of untyped lambdas · hn · 2026-09-14 · 44 upvotes · similarity 0.49
- Valk · hn · 2026-02-10 · 5 upvotes · similarity 0.48
- Han · hn · 2026-03-14 · 208 upvotes · similarity 0.45
- The Taka Programming Language · hn · 2025-12-03 · 12 upvotes · similarity 0.45
- I wrote a technical history book on Lisp · hn · 2026-02-17 · 252 upvotes · similarity 0.44
- Mach · hn · 2026-06-08 · 32 upvotes · similarity 0.44
- Topaz · hn · 2026-06-18 · 5 upvotes · similarity 0.44
- Genotype: language that compiles to idiomatic TS, Rust and Python · hn · 2026-09-08 · 9 upvotes · similarity 0.44
Other launches for this product
- No other launches for this product.
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