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Frozen

A header-only, constexpr alternative to gperf for C++14 users
1,576 stars118 forksC++Updated 4/20/2026100% free · open source
What it does

Provides header‑only, constexpr hash maps/sets so you can do fast compile‑time lookups without generating code with gperf.

When to use it
  • •You need a perfect hash table that lives entirely in the binary and can be evaluated at compile time.
  • •You want to avoid runtime initialization overhead for static lookup tables (e.g., HTTP status codes, command strings).
  • •Your project is limited to C++14 and you prefer a single‑header dependency over external code generators.
Ready-to-paste prompt
g++ -std=c++14 -O2 -I./frozen example.cpp && ./a.out   # compiles a program that uses a frozen constexpr unordered_map for HTTP status lookup
Heads up: The library needs a compiler with full C++14 constexpr support (GCC 5+ or Clang 3.9+). Older versions of MSVC will fail to compile the headers.
Saves to your device
Use with Claude
New

Skip the builder — one click puts this in Claude, Cursor, Antigravity and more.

🛠️ Technical setup

Expect 20–40 minutes in a terminal — or let your AI agent drive it.

Try it instantly — no install
Claude Code
mkdir -p ~/.claude/skills/frozen && curl -fsSL https://workflowstacks.com/api/skills/frozen/claude-skill -o ~/.claude/skills/frozen/SKILL.md
Open in another AI app

Opens the app with this repo with the prompt ready to go — no copy-paste needed.

Connect the whole catalog (MCP)
claude mcp add --transport http workflowstacks https://workflowstacks.com/api/mcp

Adds a WorkflowStacks connector to Claude Code: search and load any skill here by chatting.

How Frozen works
Codeflow
Free to inspect

Frozen is a medium C++ project (~6.2k lines across 29 code files, plus 15 test files). Expect some technical setup — comfortable with a terminal, or ask a developer. Last commit 5 months ago, Apache-2.0 license, has a test suite.

Size
Medium codebase
~6.2k lines · 29 code files · 52 min skim
Setup
Some technical setup
Comfortable with a terminal? 20–40 min. Otherwise ask a dev.
Runs on
C++
No API keys detected
C++ 98%CMake 2%
Where to start reading
  1. 1
    README.rst
    Start here — what it does and how to install it
  2. 2
    examples/CMakeLists.txt
    A worked example — copy this to get going
What's in each folder
examples/Examples you can copy7 files
include/Folder19 files
benchmarks/Evaluations & benchmarks7 files
cmake/Folder4 files
tests/Tests — proof it works17 files
.github/CI / automation (GitHub Actions)3 files
READMEHas testsDocumentedCI checksExamples includedApache-2.0 licenseUpdated 5 mo ago
Quick Actions
Details
Creator
serge-sans-paille
Language
C++
Category
ai-agent
Published
5/22/2017

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Featured on WorkflowStacks
[![Featured on WorkflowStacks](https://workflowstacks.com/api/badge/frozen.svg)](https://workflowstacks.com/skills/frozen?utm_source=github&utm_medium=badge)
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