Data.Builder.Catenable

Builder with cheap concatenation. Like the builder type from Data.Builder.ST, this builder can be stored somewhere and this used again later. However, this builder type has several advantages:

• Supports both cons and snoc (Data.Builder.ST only supports snoc)
• No linear-use restriction
• Extremely cheap concatenation (not supported by Data.Builder.ST at all)

In exchange for all of these, this implementation trades performance. Performance is degraded for two reasons:

• Evaluation of the builder is deferred, and the evaluation requires walking a tree of nodes.
• This builder stores individual elements rather than chunks. There is no fundamental reason for this. It is possible to store a SmallArray in each Cons and Snoc instead, but this makes the implementation a little more simple.

One reason to prefer this module instead of Data.Builder.ST is that this module lets the user works with builder in a more monoidal style rather than a stateful style. Consider a data type with several fields that is being converted to a builder. Here, Data.Builder.ST would require that Builder appear as both an argument and an result for each field's encode function. The linearly-used builder must be threaded through by hand or by clever use of StateT. With Data.Builder.Catenable, the encode functions only need return the builder.

Type

data Builder a

Constructors

Empty

Cons a !(Builder a)

Snoc !(Builder a) a

Append !(Builder a) !(Builder a)

Instances

IsList (Builder a)

Defined in Data.Builder.Catenable

Associated Types

type Item (Builder a)

Methods

fromList :: [Item (Builder a)] -> Builder a

fromListN :: Int -> [Item (Builder a)] -> Builder a

toList :: Builder a -> [Item (Builder a)]

Semigroup (Builder a)

Defined in Data.Builder.Catenable

Methods

(<>) :: Builder a -> Builder a -> Builder a

sconcat :: NonEmpty (Builder a) -> Builder a

stimes :: Integral b => b -> Builder a -> Builder a

Monoid (Builder a)

Defined in Data.Builder.Catenable

Methods

mempty :: Builder a

mappend :: Builder a -> Builder a -> Builder a

mconcat :: [Builder a] -> Builder a

type Item (Builder a)

Defined in Data.Builder.Catenable

type Item (Builder a) = a

Convenient infix operators

pattern (:<) :: a -> Builder a -> Builder a infixr 5

pattern (:>) :: Builder a -> a -> Builder a infixl 5

Run

run :: Builder a -> Chunks a