Portability	portable to Hugs and GHC
Stability	experimental
Maintainer	Johan Tibell <johan.tibell@gmail.com>
Safe Haskell	Trustworthy

Data.Text.Lazy.Builder

Contents

The Builder type
Constructing Builders
Flushing the buffer state

Description

Efficient construction of lazy Text values. The principal operations on a Builder are singleton, fromText, and fromLazyText, which construct new builders, and mappend, which concatenates two builders.

To get maximum performance when building lazy Text values using a builder, associate mappend calls to the right. For example, prefer

 singleton 'a' `mappend` (singleton 'b' `mappend` singleton 'c')

to

 singleton 'a' `mappend` singleton 'b' `mappend` singleton 'c'

as the latter associates mappend to the left. Or, equivalently, prefer

 singleton 'a' <> singleton 'b' <> singleton 'c'

since the <> from recent versions of Monoid associates to the right.

Synopsis

The Builder type

data Builder Source

A Builder is an efficient way to build lazy Text values. There are several functions for constructing builders, but only one to inspect them: to extract any data, you have to turn them into lazy Text values using toLazyText.

Internally, a builder constructs a lazy Text by filling arrays piece by piece. As each buffer is filled, it is 'popped' off, to become a new chunk of the resulting lazy Text. All this is hidden from the user of the Builder.

Instances

Eq Builder
Ord Builder
Show Builder
IsString Builder
Monoid Builder

toLazyText :: Builder -> Text Source

O(n). Extract a lazy Text from a Builder with a default buffer size. The construction work takes place if and when the relevant part of the lazy Text is demanded.

toLazyTextWith :: Int -> Builder -> Text Source

O(n). Extract a lazy Text from a Builder, using the given size for the initial buffer. The construction work takes place if and when the relevant part of the lazy Text is demanded.

If the initial buffer is too small to hold all data, subsequent buffers will be the default buffer size.

Constructing Builders

singleton :: Char -> Builder Source

O(1). A Builder taking a single character, satisfying

```
toLazyText (singleton c) = singleton c
```

fromText :: Text -> Builder Source

O(1). A Builder taking a Text, satisfying

toLazyText (fromText t) = fromChunks [t]

fromLazyText :: Text -> Builder Source

O(1). A Builder taking a lazy Text, satisfying

```
toLazyText (fromLazyText t) = t
```

fromString :: String -> Builder Source

O(1). A Builder taking a String, satisfying

toLazyText (fromString s) = fromChunks [S.pack s]

Flushing the buffer state

flush :: Builder Source

O(1). Pop the strict Text we have constructed so far, if any, yielding a new chunk in the result lazy Text.