Sequences
Clojure provides sequence abstraction over many of its data structures(even maps) which provides a lot of functions and helps working with sequential things
- Sequences are abstraction for representing iterations
- Sequences can be backed by data structures or functions
- When backed by functions, they can be lazy and infinite
- Its a foundation for large library functions
Sequence API
(seq col)take collection and return next(first coll)return first element(rest coll)take out first and return rest(cons x coll)returns a new collection with x as first element e.g.(println (cons "a" ["l", "s", "e"])) ;;=>(a l s e)
Sequence Functions
Sequence functions can be divided roughly into two categories.
- Generators - generators are used to generate lazy sequences from the data, functions, or other objects provided e.g. list, vector, map, SQL ResultSet, Stream, Directory etc.
- Operations - operations and functions that perform some operation and return another sequence or some other data structure e.g map, reduce, filter, count, some, replace