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Feather

a fresh Tcl reimplementation (WASM, Go)

Details

External ID
46401944
Source
HN
Company
—
Product
Feather
Website domain
feather-lang.dev
Launched
Dec. 27, 2025
Cohort
—
Upvotes
31
Upvotes percentile
0.7366412213740458
Tags
—
Fetched at
Sept. 7, 2026, 9:25 p.m.
Updated at
Sept. 7, 2026, 9:25 p.m.

Description

Hey HN!First time showing something here, but I've been furiously working over the holidays on Feather, a from scratch reimplementation of TCL designed for embedding in modern applications.It's starting out as a faithful reimplementation of TCL without I/O, OOP features, or coroutines.TCL has a special place in my heart because the syntax is so elegant for interactive use, and defining domain specific languages.My motiviation is twofold: faster feedback loops for AI, and moldable software for users.It turns out giving AI agents access to the runtime state of your program makes for really fast feedback loops, but embedding existing options in a world where shipping binaries for each platform is commonplace is tricky.Embedding the real TCL is tricky because it comes with its own event loop (in 2025 you alreay have one), a GUI framework (you have a web framework already, or develop on mobile), and has access to the filesystem (don't forget to delete all commands with file system access!).Feather just doesn't ship with those - expose only what you need from your application.A WASM build comes out of the box and clocks in at ~120kb plus 70kb for connecting it to the browser or node.js.And if embedding becomes easy, you can put a REPL everywhere: in mobile apps, in desktop software, as a control plane into web servers.I want to imagine a world where all software is scriptable just like Emacs and nvim, with agents doing the actual work.

Enrichment

Theme
browser automation and scraping for AI
Vertical
Horizontal
Function
Dev tools
Audience
Developer
AI stance
Not AI
Project type
Hobby / open-source project
Normalized one-liner
tcl reimplementation in wasm and go
Manually corrected
False

Could you build this?

No Writing a faithful, embeddable programming language interpreter with WASM compilation from scratch requires deep compiler and interpreter design expertise.

What it would actually take: A developer needs extensive knowledge of interpreter design, lexical analysis, AST generation, and runtime evaluation mechanics in Go, followed by compiling to WebAssembly. Reimplementing Tcl entails faithfully modeling its unique 'everything is a string' execution model, variable scoping rules (upvar/uplevel), and control structures without relying on modern off-the-shelf parser generators.

Discussion

5 comments analyzed.

Competitors mentioned: Jimtcl, Original Tcl

Concerns raised: Name confusion with existing old Feather project, Reference counting complexity

Feature requests: WASM browser support, First-class multithreading support

Competitors

Other products that read as similar to this one — 70 launches clear the similarity bar, closest 8 shown.

Attention rank: #26 of 71 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).

Launched 57 days after the earliest competitor.

Other launches for this product

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