HLRDB.Primitives.Redis

A model for categorizing Redis commands for their particular structures using a GADT.

Documentation

data TrimScheme

List and SSet declarations allow you to provide a TrimScheme. When provided, HLRDB will automatically trim the structure to the desired cardinality whenever data is inserted.

For example, if you set a softCardinality of 100 and a trimProbability of 0.05, whenever a data insertion takes place that could bring the cardinality over 100, there will be a 5% chance that a trim command will also be executed. If you want a hard cardinality (to the extent that Redis provides any guarantees), simply set the probability to 1. If you do not want any automatic trimming, simply do not provide a TrimScheme.

Constructors

TrimScheme

Fields

• softCardinality :: Integer
• trimProbability :: Double

data RedisStructure t a b where

GADT declaring the major Redis data structures. For application-level logic, the simpler type aliases declared below should suffice.

Constructors

RKeyValue :: E Maybe a b -> RedisStructure (BASIC ()) a b

RKeyValueInteger :: (a -> ByteString) -> (b -> Integer) -> (Integer -> b) -> RedisStructure (BASIC Integer) a b

RKeyValueByteString :: (a -> ByteString) -> RedisStructure (BASIC ByteString) a ByteString

RList :: RE a b -> Maybe TrimScheme -> RedisStructure LIST a b

RHSet :: RE a b -> HSET v -> RedisStructure (HSET v) a b

RSet :: RE a b -> RedisStructure SET a b

RSortedSet :: RE a b -> Maybe TrimScheme -> RedisStructure SORTEDSET a b

type RedisBasic k v = RedisStructure (BASIC ()) k v

Alias for simple key-value storage

type RedisIntegral k v = RedisStructure (BASIC Integer) k v

Alias for simple Integer storage

type RedisByteString k v = RedisStructure (BASIC ByteString) k ByteString

Alias for indexable ByteString storage, allowing getting and setting ranges within the value. To enforce consistency across the low-level getrange/setrange commands, non-existent values are transparently rendered as empty ByteStrings. Note that the maximum size permitted in a single value by Redis is 512 MB.

type RedisList k v = RedisStructure LIST k v

Alias for a Redis List

type RedisHSet k s v = RedisStructure (HSET s) k v

Alias for a Redis HSet

type RedisSet k v = RedisStructure SET k v

Alias for a Redis Set

type RedisSSet k v = RedisStructure SORTEDSET k v

Alias for a Redis SortedSet

data ActionPerformed a where

Many commands in Redis return information about whether items were added/removed or merely updated

Constructors

FreshlyCreated :: Integer -> ActionPerformed Creation

Deleted :: Integer -> ActionPerformed Deletion

data E f a b

General primitive encoding. We need a way to serialize the key, and a way to both serialize and deserialize values.

Constructors

E (a -> ByteString) (b -> f ByteString) (f ByteString -> b)

type RE a b = E Identity a b

Most structures don't rely on any special context

data BASIC a

Type-level indicator for Redis basic types

data LIST

Type-level indicator for Redis Lists

data HSET k

Type-level indicator for Redis HSets with sub-keys of type k; requires a way to serialize and deserialize sub-keys

Constructors

HSET (k -> ByteString) (ByteString -> k)

data SET

Type-level indicator for Redis Sets

data SORTEDSET

Type-level indicator for Redis SortedSets

data Creation

Type-level indicator for Creation

data Deletion

Type-level indicator for Deletion