Interactive Common Lisp: An Enhanced REPL
Details
- External ID
- 46259671
- Source
- HN
- Company
- —
- Product
- Interactive Common Lisp: An Enhanced REPL
- Website domain
- github.com
- Launched
- Dec. 14, 2025
- Cohort
- —
- Upvotes
- 101
- Upvotes percentile
- 0.9007633587786259
- Tags
- —
- Fetched at
- Sept. 7, 2026, 9:25 p.m.
- Updated at
- Sept. 7, 2026, 9:25 p.m.
Description
I created this because sometimes I want more than rlwrap but less than emacs. icl aims to hit that middle sweet spot.It's a terminal application with context-aware auto-complete, an interactive object inspector, auto-indentation, syntax colouring, persistent history, and much more. It uses sly to communicate with the child lisp process and aims to be compatible with any sly-supporting implementation. I hope others find it useful!
Enrichment
- Theme
- markdown editors and writing tools
- Vertical
- Horizontal
- Function
- Dev tools
- Audience
- Developer
- AI stance
- Not AI
- Project type
- Hobby / open-source project
- Normalized one-liner
- enhanced repl for common lisp
- Manually corrected
- False
Could you build this?
Partial While terminal UIs can be scaffolded, building a stable, interactive Lisp REPL that communicates via Sly/Swank protocols, handles complex Common Lisp reader macros, and manages live runtime introspection requires deep Lisp internals expertise.
What it would actually take: The architecture involves a TUI library (e.g., in Go with Bubbletea, or Common Lisp with cl-charms) connecting over sockets to a Slynk/Swank backend server running in an SBCL process. The hard part is managing asynchronous protocol communication with Slynk, parsing Lisp forms accurately for interactive completion/indentation, and cleanly handling SBCL debugger breaks and signals in the terminal.
Discussion
9 comments analyzed.
Competitors mentioned: cl-repl, Allegro IDE, LispWorks IDE, Slime, rlwrap
Concerns raised: Installation/connection issues with Slynk/Swank servers, Pasting code with long lines doesn't work well, Lacks interactive debugger (only backtrace command), Missing reverse-search-history and history-search-backward keyboard shortcuts, Slower launch time compared to alternatives
Feature requests: Add reverse-search-history (C-r) and history-search-backward (M-p) keyboard shortcuts, Improve paste handling for multi-line code, Add interactive debugger capabilities
Competitors
Other products that read as similar to this one — 25 launches clear the similarity bar, closest 8 shown.
Attention rank: #5 of 26 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 39 days after the earliest competitor.
- Julius, a New Lisp Implementation · hn · 2026-05-03 · 14 upvotes · similarity 0.43
- Ced · hn · 2026-05-07 · 5 upvotes · similarity 0.42
- A Common Lisp implementation in development · hn · 2026-04-05 · 7 upvotes · similarity 0.41
- An implementation of Common Lisp in development, reached version 1.6 · hn · 2026-05-12 · 27 upvotes · similarity 0.40
- I wrote a technical history book on Lisp · hn · 2026-02-17 · 252 upvotes · similarity 0.38
- I forced Claude to play Tetris in Emacs · hn · 2026-04-11 · 13 upvotes · similarity 0.38
- DiagramIDE · hn · 2026-02-27 · 6 upvotes · similarity 0.37
- GDSL · hn · 2026-03-15 · 89 upvotes · similarity 0.37
Other launches for this product
- No other launches for this product.
Same idea, different domain
Nobody's really built a dev tools tool for Sales yet.