Data.Text.Internal.Fusion

Warning: this is an internal module, and does not have a stable API or name. Functions in this module may not check or enforce preconditions expected by public modules. Use at your own risk!

Text manipulation functions represented as fusible operations over streams.

Types

data Stream a

A co-recursive type yielding a single element at a time depending on the internal state it carries.

Constructors

forall s. Stream (s -> Step s a) !s !Size

Instances

Eq a => Eq (Stream a)

Defined in Data.Text.Internal.Fusion.Types

Methods

(==) :: Stream a -> Stream a -> Bool

(/=) :: Stream a -> Stream a -> Bool

Ord a => Ord (Stream a)

Defined in Data.Text.Internal.Fusion.Types

Methods

compare :: Stream a -> Stream a -> Ordering

(<) :: Stream a -> Stream a -> Bool

(<=) :: Stream a -> Stream a -> Bool

(>) :: Stream a -> Stream a -> Bool

(>=) :: Stream a -> Stream a -> Bool

max :: Stream a -> Stream a -> Stream a

min :: Stream a -> Stream a -> Stream a

data Step s a

Intermediate result in a processing pipeline.

Constructors

Done

Skip !s

Yield !a !s

Creation and elimination

stream :: Text -> Stream Char

O(n) Convert Text into a Stream Char.

Properties

unstream . stream = id

stream . unstream = id

streamLn :: Text -> Stream Char

O(n) streamLn t = stream (t <> '\n')

Since: 2.1.2

unstream :: Stream Char -> Text

O(n) Convert Stream Char into a Text.

Properties

unstream . stream = id

stream . unstream = id

reverseStream :: Text -> Stream Char

O(n) Converts Text into a Stream Char, but iterates backwards through the text.

Properties

unstream . reverseStream = reverse

length :: Stream Char -> Int

O(n) Returns the number of characters in a Stream.

Properties

length . stream = length

Transformations

reverse :: Stream Char -> Text

O(n) Reverse the characters of a Stream returning Text.

Properties

reverse . stream = reverse

Construction

Scans

reverseScanr :: (Char -> Char -> Char) -> Char -> Stream Char -> Stream Char

O(n) Perform the equivalent of scanr over a list, only with the input and result reversed.

Properties

reverse . reverseScanr f c . reverseStream = scanr f c

Accumulating maps

mapAccumL :: (a -> Char -> (a, Char)) -> a -> Stream Char -> (a, Text)

O(n) Like a combination of map and foldl'. Applies a function to each element of a Text, passing an accumulating parameter from left to right, and returns a final Text.

Properties

mapAccumL g z0 . stream = mapAccumL g z0

Generation and unfolding

unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Stream Char

O(n) Like unfoldr, unfoldrN builds a stream from a seed value. However, the length of the result is limited by the first argument to unfoldrN. This function is more efficient than unfoldr when the length of the result is known.

Properties

unstream (unfoldrN n f a) = unfoldrN n f a

Indexing

index :: HasCallStack => Stream Char -> Int -> Char

O(n) stream index (subscript) operator, starting from 0.

Properties

index (stream t) n  = index t n

findIndex :: (Char -> Bool) -> Stream Char -> Maybe Int

The findIndex function takes a predicate and a stream and returns the index of the first element in the stream satisfying the predicate.

Properties

findIndex p . stream  = findIndex p

countChar :: Char -> Stream Char -> Int

O(n) The count function returns the number of times the query element appears in the given stream.

Properties

countChar c . stream  = countChar c