jwoudenberg/fantasy-dict

Fantasy-land compatible dictionary.

fantasy-dict

A dictionary implementing the fantasy-land Monoid, Functor, Foldable and Traversable specifications.

Use this when a plain old javascript object as a map won't do, because you want to combine it with some fantasy-land compatible library like Ramda.

API

Apart from the fantasy-land required methods, the following methods are supported:

Dict :: { k: * } -> Dict *

Create a dictionary from a plain javascript object.

Dict.singleton :: String -> x -> Dict x

Create a dictionary with a single key,value pair.

Dict.prototype.insert :: Dict * ~> String -> x -> Dict *

Returns a new dictionary equal to the previous dictionary with the passed in key,value pair inserted.

Dict.prototype.delete :: Dict * ~> String -> Dict *

Returns a new dictionary equal to the previous dictionary with the passed in key removed.

Dict.prototype.reduceWithKey :: Dict * ~> (a -> String -> b -> a) -> a -> a

Like the normal reduce, with the difference that the reducer function is also passed the key of each dictionary entry.

Dict.prototype.mapWithKey :: Dict a ~> (String -> a -> b) -> Dict b

Like the normal reduce, with the difference that the reducer function is also passed the key of each dictionary entry.

Dict.prototype.lookup :: Dict * ~> String -> *

Returns the value in the dictionary for the given key. Returns undefined if the passed in key is not in the dictionary.

Dict.prototype.keys :: Dict * ~> [ String ]

Returns an array containing the dictionary's keys.

Dict.prototype.values :: Dict * ~> [ * ]

Returns an array containing the dictionary's values.

Dict.prototype.toObject :: Dict * ~> { k: * }

Returns the plain old javascript object equivalent of a dictionary.