Analyze.Decoding

Applicative decoding with key-value lookups. Think of a Decoder as a row function that exposes the columns it uses.

Documentation

data Arg m k v a

Pair of key and an extraction function.

Constructors

Arg k (v -> m a)

Instances

Functor m => Functor (Arg m k v)

Methods

fmap :: (a -> b) -> Arg m k v a -> Arg m k v b

(<$) :: a -> Arg m k v b -> Arg m k v a

newtype Decoder m k v a

Free applicative over Arg.

Constructors

Decoder (Ap (Arg m k v) a)

Instances

Functor (Decoder m k v)

Methods

fmap :: (a -> b) -> Decoder m k v a -> Decoder m k v b

(<$) :: a -> Decoder m k v b -> Decoder m k v a

Applicative (Decoder m k v)

Methods

pure :: a -> Decoder m k v a

(<*>) :: Decoder m k v (a -> b) -> Decoder m k v a -> Decoder m k v b

(*>) :: Decoder m k v a -> Decoder m k v b -> Decoder m k v b

(<*) :: Decoder m k v a -> Decoder m k v b -> Decoder m k v a

decoderKeys :: Data k => Decoder m k v a -> [k]

List all column names used in the Decoder.

fromArg :: Arg m k v a -> Decoder m k v a

Lifts a single Arg into a Decoder

require :: Applicative m => k -> Decoder m k v v

Simple Decoder that just looks up and returns the value for a given key.

requireWhere :: k -> (k -> v -> m a) -> Decoder m k v a

Shorthand for lookup and transform.

runDecoder :: (Data k, Monad m) => Decoder m k v a -> (k -> m v) -> m a

Run a Decoder with a lookup function (typically row lookup).