redis

A Redis client library for Carp, supporting Redis 7.x.

Installation

(load "https://git.veitheller.de/carpentry/redis.git@0.2.0")

Usage

(load "redis.carp")

(defn main []
  (match (Redis.open "127.0.0.1")
    (Result.Success r)
      (do
        (println* &(Redis.ping &r))
        (println* &(Redis.set &r @"key" @"value"))
        (println* &(Redis.get &r @"key"))

        ; list operations return nested RESP arrays
        (println* &(Redis.rpush &r @"mylist" @"a"))
        (println* &(Redis.rpush &r @"mylist" @"b"))
        (println* &(Redis.lrange &r @"mylist" @"0" @"-1"))

        ; pattern match on responses
        (match (Redis.get &r @"key")
          (Result.Success resp)
            (match resp
              (RESP.Str s) (println* "got: " &s)
              (RESP.Null) (println* "key not found")
              _ (println* "unexpected type"))
          (Result.Error e) (println* "error: " &e))

        (Redis.close r))
    (Result.Error err) (IO.errorln &err)))

The library provides thin wrappers around all standard Redis commands through 7.2, so you can call them directly (e.g. Redis.get, Redis.hset, Redis.lrange). For commands with complex or variadic arguments, use Redis.send directly:

(Redis.send &r @"SET" &[(to-redis @"key") (to-redis @"value")])
(Redis.read &r)

The RESP type supports recursive arrays via Box, so nested structures (e.g. from XRANGE or COMMAND) are decoded faithfully.

Pub/sub

After subscribing you can receive the stream of pushed messages with Redis.next-message, which decodes each reply into a typed PubSubMessage:

(match (Redis.subscribe &r @"news")
  (Result.Success _)
    (match (Redis.next-message &r)
      (Result.Success msg)
        (match msg
          (PubSubMessage.Message channel payload)
            (println* "got " &payload " on " &channel)
          (PubSubMessage.Subscribe channel count)
            (println* "subscribed to " &channel)
          _ (println* "other pub/sub reply"))
      (Result.Error e) (IO.errorln &e))
  (Result.Error e) (IO.errorln &e))

PubSubMessage covers Message, PMessage (pattern subscriptions), and the Subscribe/Unsubscribe/PSubscribe/PUnsubscribe confirmations. To keep processing messages in a loop, hand Redis.listen a callback — it runs until the connection errors out.

Full API documentation lives here.

More examples are in the examples directory.

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Have fun!