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Klong (K) on Miren

Klong is an open-source array language in the K/APL family. Array languages don't ship HTTP servers, so — as with COBOL and Bash — this guide has the Klong program print an HTTP response and puts socat in front of it to own the socket. It uses KlongPy, a pip-installable Klong implementation.

Let your agent do this

Ask your AI coding agent to "set up this Klong app on Miren" after installing the Miren agent skills. It adds the Dockerfile.miren and the socket front-end, and deploys — using this page as its reference.

Do you need a Dockerfile?​

Yes. Add a Dockerfile.miren to your project root. Miren builds from it instead of guessing the stack — see Using Dockerfile.miren.

Want native support?

Miren auto-detects and builds common stacks (Python, Node, Bun, Go, Ruby, Rust) without a Dockerfile. This language isn't one of them yet — if you'd like first-class support, request it.

The program​

.d writes a string to standard output verbatim. Put a complete HTTP response — status line, headers, a blank line, then the body — in hello.kg:

.d("HTTP/1.1 200 OK
Content-Type: text/plain
Connection: close

Hello from Klong on Miren!
")
Run Klong from a file for clean output

Run the program as a file (kgpy hello.kg), not with -e or over a pipe — those start the REPL and echo the expression result ("…" with quotes) alongside your output. In file mode only your .d bytes are written.

The socket front-end​

The program doesn't bind a port — socat does. Miren injects PORT, and socat's TCP-LISTEN binds all interfaces; fork runs Klong once per connection:

web: socat TCP-LISTEN:$PORT,reuseaddr,fork EXEC:'kgpy /app/hello.kg'
Behind Miren's ingress

Miren's HTTP ingress terminates TLS and handles the public HTTP layer in front of your app, so socat only needs to hand each accepted connection to your program — it isn't exposed to raw internet traffic. The one practical limit is that fork spawns a process per request, so this suits low-traffic endpoints and tooling rather than high-throughput services.

The Dockerfile​

Create Dockerfile.miren in your project root. KlongPy installs from PyPI (it also needs colorama for its CLI), and socat comes from apt:

FROM python:3.12-slim
RUN pip install --no-cache-dir klongpy colorama \
    && apt-get update -y && apt-get install -y socat && rm -rf /var/lib/apt/lists/*
WORKDIR /app
COPY hello.kg /app/
EXPOSE 8080

.dockerignore​

.git

Deploy​

Create .miren/app.toml naming your app and deploy from your project root:

name = "klong-bench"
miren deploy
The Procfile is required

Even with a Dockerfile.miren, Miren needs at least one service defined — the web: line above. Without it the deploy stops with no services defined.

Agent quick reference​

  • Detection: none — requires Dockerfile.miren
  • Runtime: KlongPy (pip install klongpy colorama) on python:3.12-slim
  • Serving: the Klong program .d-prints a full HTTP response; socat owns the socket
  • Run from a file: kgpy hello.kg (file mode) — -e/pipe modes echo the result too
  • Service is required: Procfile web: socat TCP-LISTEN:$PORT,reuseaddr,fork EXEC:'kgpy /app/hello.kg'
  • Port: socat TCP-LISTEN:$PORT binds 0.0.0.0

Next steps​