Added a Redis/Valkey extension named redis. (0.42.0)

web/documentation/extensions/redis/redis.md

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+---
+layout: page
+published: true
+noToc: false
+noComments: false
+noDate: false
+title: Redis (hiredis) Extension
+subtitle: Redis client integration for Fun using the hiredis C library.
+description: Documentation for the optional Redis extension in Fun. Provides redis_connect, redis_cmd, and redis_close builtins backed by hiredis.
+permalink: /documentation/extensions/redis/
+lang: en
+tags:
+- redis
+- hiredis
+- database
+- cache
+- extension
+- networking
+- async
+---
+
+The Redis extension adds a minimal client for Redis-compatible servers using the [hiredis](https://github.com/redis/hiredis){:class="ext"} C library. It currently exposes a simple synchronous API; Async I/O through Fun's event loop will be added later.
+
+Requirements
+------------
+- Build-time option: `-DFUN_WITH_REDIS=ON`
+- System libraries: `hiredis` headers and library available (via pkg-config or default linker search paths)
+- Runtime: a Redis-compatible server (e.g., on `127.0.0.1:6379`)
+
+Enabling the extension
+----------------------
+Example CMake configure line enabling Redis along with other options:
+
+<pre>cmake -S . -B build_release -DCMAKE_BUILD_TYPE=Release \
+  -DFUN_WITH_REDIS=ON -DFUN_WITH_OPENSSL=ON</pre>
+
+When configured, the build summary will include a line:
+
+<pre>Redis (FUN_WITH_REDIS): ENABLED</pre>
+
+Provided builtins/opcodes
+-------------------------
+- `redis_connect(host: string, port: int) -> int`
+  - Establishes a TCP connection and returns a positive handle id on success, or `0` on error.
+  - Example: `h = redis_connect('127.0.0.1', 6379)`
+
+- `redis_cmd(handle: int, cmd: string) -> Value`
+  - Executes a Redis inline command string and returns the reply as a Fun value.
+  - Reply mapping:
+    - Status/String -> string
+    - Integer -> number
+    - Nil -> `nil`
+    - Array -> array of recursively converted values
+  - Example: `print(redis_cmd(h, 'PING'))`  ⇒ `PONG`
+
+- `redis_close(handle: int) -> Nil`
+  - Closes the connection associated with the handle and frees resources.
+
+Notes and limitations
+---------------------
+- Error handling: invalid handles or failed commands yield `nil` or an empty/neutral value depending on context.
+- Security: this initial version does not include TLS; TLS support may be added in a future iteration once hiredis SSL is wired in.
+- Async: the current API is synchronous. Integration with Fun's asyncio is planned.
+
+Examples
+--------
+Runnable examples are included in the source tree:
+
+- `examples/extensions/redis/basic_ping.fun`
+- `examples/extensions/redis/kv_set_get.fun`
+- `examples/extensions/redis/list_ops.fun`
+- `examples/extensions/redis/hash_ops.fun`
+
+Quick start (from repo root, using a built Fun executable):
+
+<pre>build_debug/fun examples/extensions/redis/basic_ping.fun</pre>
+
+Troubleshooting
+---------------
+- Ensure a Redis server is reachable at the host/port you pass to `redis_connect`.
+- If `redis_connect` returns `0`, verify the hiredis library and headers are installed and that Fun was configured with `-DFUN_WITH_REDIS=ON`.