What is morloc CLAUDE.md?

Project instructions for Morloc, a typed workflow language that combines code written in Python, C++, and R. A typed language checks that values are used in compatible ways.

Use them when changing Morloc's Haskell code, shared data or bindings, running tests, rebuilding generated components, or reviewing performance-sensitive code.

They highlight rules that matter to this project, including treating errors seriously and protecting performance for both tiny and very long-running programs. They also identify the checks required after code changes.

How morloc-project/morloc configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to morloc-project/morloc. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/morloc-project/morloc/master/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/morloc-project/morloc

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/morloc-project/morloc/claude-md/github.svg)](https://agentmods.dev/instructions/morloc-project/morloc/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/morloc-project/morloc/claude-md"><img src="https://agentmods.dev/badge/instructions/morloc-project/morloc/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/morloc-project/morloc/claude-md"><img src="https://agentmods.dev/badge/instructions/morloc-project/morloc/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,642 This file is loaded in full into every session.

When invoked 1,642 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.01642	$0.01642
Opus 5.5	$0.00657	$0.00657
Sonnet 5.5	$0.00328	$0.00328
Haiku 4.5	$0.00164	$0.00164

Measured 14d ago against content hash e8a967dc8794, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

morloc CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 14d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 161 lines

How it starts

The opening of the file, as written. The whole thing — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

Guidance for Claude Code when working with this repository.

Project Overview

Morloc is a multi-lingual typed workflow language enabling function composition across Python, C++, and R under a unified type system.

General Rules

See @../../../CONVENTIONS.md for the workspace-wide rules (git, bug reporting, correctness, test-first, comments, ASCII-only). Repo-specific rules follow.

Performance is critical
- Morloc programs may run for days or nanoseconds
- All between process communication must be as fast as possible (a cross-language round trip targets about 20 us; the floor is about 13 us, see model/performance/cross-language.md XL-1), and yet the processes must accommodate very large packets and programs that run for a very long time.

Checking code

After making a substantial change to the Haskell code, run:

$ stack install --no-run-tests $ stack test morloc:morloc-test # This is the usual test

To run the full heavy integrated test suite, run:

$ stack test # ONLY do this at the very end of a session; IT IS EXPENSIVE

If you make any change to the non-haskell code in data/, then you MUST run

$ MORLOC_RUST_DIR=$PWD/data/rust morloc init -f

from the repo root. This rebuilds shared libraries, the nexus executable, and language bindings. MORLOC_RUST_DIR is required: a bare morloc init -f rebuilds from the installed copy of the runtime sources, not your working tree, so your edit is silently absent from the library under test and the change appears to have no effect.

After changing anything under data/rust/, run:

$ cargo test --workspace --manifest-path data/rust/Cargo.toml

Stack test runs unit tests and golden-tests
Golden-tests are full morloc programs
- Each golden test is in the path @test-suite/golden-tests/
- Every directory there is discovered and run; nothing needs registering
- These tests produce build errors in build.err and runtime errors in obs.err. These outputs are VITAL to debugging errors.

Read the full file on GitHub · 161 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

14d ago Changed · +39 lines · +525 tokens per session e8a967dc8794
1mo ago Changed · +29 lines · +386 tokens per session 8d1ffbc80144
2mo ago Changed · +7 lines · +98 tokens per session a298cec61147
2mo ago First seen · 86 lines · 633 tokens per session scan A fd8dedd4edca

Subscribe to this mod's changes

morloc CLAUDE.md is an instructions file published in the GitHub repository morloc-project/morloc (219 stars, last pushed 5d ago), licensed Apache-2.0. It adds 1,642 tokens to every session, about $0.0066 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Code Generation Languages functional-language language polyglot programming-language type-system

morloc CLAUDE.md next to 6 instructions from other repositories
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morloc: Instructions file for Claude Code