Portability | portable |
---|---|

Stability | beta |

Maintainer | wren@community.haskell.org |

- data Trie a
- type KeyString = ByteString
- type KeyElem = ByteStringElem
- showTrie :: Show a => Trie a -> String
- empty :: Trie a
- null :: Trie a -> Bool
- singleton :: KeyString -> a -> Trie a
- size :: Trie a -> Int
- toListBy :: (KeyString -> a -> b) -> Trie a -> [b]
- lookupBy_ :: (Maybe a -> Trie a -> b) -> b -> (Trie a -> b) -> KeyString -> Trie a -> b
- submap :: KeyString -> Trie a -> Trie a
- alterBy :: (KeyString -> a -> Maybe a -> Maybe a) -> KeyString -> a -> Trie a -> Trie a
- mergeBy :: (a -> a -> Maybe a) -> Trie a -> Trie a -> Trie a
- mapBy :: (KeyString -> a -> Maybe b) -> Trie a -> Trie b
- filterMap :: (a -> Maybe b) -> Trie a -> Trie b

# Data types

A map from `ByteString`

s to `a`

. For all the generic functions,
note that tries are strict in the `Maybe`

but not in `a`

.

The `Monad`

instance is strange. If a key `k1`

is a prefix of
other keys, then results from binding the value at `k1`

will
override values from longer keys when they collide. If this is
useful for anything, or if there's a more sensible instance, I'd
be curious to know.

type KeyString = ByteStringSource

# Basic functions

# Conversion functions

toListBy :: (KeyString -> a -> b) -> Trie a -> [b]Source

Convert a trie into a list using a function. Resulting values are in sorted order according to the keys.

# Query functions

lookupBy_ :: (Maybe a -> Trie a -> b) -> b -> (Trie a -> b) -> KeyString -> Trie a -> bSource

Generic function to find a value (if it exists) and the subtrie rooted at the prefix. The first function argument is called if and only if a node is exactly reachable by the query; if no node is exactly reachable the default value is used; if the middle of an arc is reached, the second function argument is used.

This function is intended for internal use. For the public-facing
version, see `lookupBy`

in Data.Trie.

submap :: KeyString -> Trie a -> Trie aSource

Return the subtrie containing all keys beginning with a prefix.

# Single-value modification

alterBy :: (KeyString -> a -> Maybe a -> Maybe a) -> KeyString -> a -> Trie a -> Trie aSource

Generic function to alter a trie by one element with a function to resolve conflicts (or non-conflicts).

# Combining tries

mergeBy :: (a -> a -> Maybe a) -> Trie a -> Trie a -> Trie aSource

Combine two tries, using a function to resolve collisions. This can only define the space of functions between union and symmetric difference but, with those two, all set operations can be defined (albeit inefficiently).