Clojure Methods Reference

Returns a lazy sequence consisting of the result of applying f to each item in coll. When multiple collections are provided, f is applied to corresponding items from each collection.

Returns a lazy sequence of the items in coll for which (pred item) returns a logically true value.

Reduces a collection to a single value by applying f, a function of two arguments, to an accumulator and each element. If init is not supplied, the first item of coll is used.

Returns the first item in the collection. If coll is nil or empty, returns nil.

Returns a possibly empty sequence of the items after the first. Returns an empty sequence (not nil) when there are no more items.

Returns a new seq where x is the first element and seq is the rest.

Returns a new collection consisting of to with all items from from conj-ed onto it. Supports an optional transducer.

Returns a lazy sequence of the first n items in coll, or all items if there are fewer than n.

Returns a sorted sequence of the items in coll. Uses natural ordering by default, or a custom comparator if provided.

Splits string s on a regular expression re. Returns a vector of strings.

Returns a string of all elements in coll, separated by an optional separator.

Removes leading and trailing whitespace from string s.

Replaces all instances of match with replacement in string s. Match can be a string or regex.

Returns a new map with the given key-value pair(s) added or updated. When used with vectors, sets the value at the given index.

Returns a new map without the entry for the given key(s). If the key is not present, returns the map unchanged.

Returns the value mapped to key in the associative collection. Returns not-found or nil if the key is not present.

Returns a map that consists of the rest of the maps conj-ed onto the first. If a key occurs in more than one map, the mapping from the latter map is used.

Returns a new map with the value at key updated by applying function f to the old value and any additional args. If the key does not exist, f is applied to nil.

Returns a new set with the element(s) added. conj is the primary way to add elements to any Clojure collection; for sets, duplicates are ignored.

Returns a new set without the specified element(s). If the element is not present, returns the set unchanged.

Returns a set that is the union of the input sets: all elements from all sets combined.

Takes a set of functions and returns a function that is the composition of those functions. The returned function takes a variable number of args, applies the rightmost function, then applies each remaining function to the result, right-to-left.

Takes a function f and fewer than the normal arguments to f, and returns a function that takes the remaining arguments. When called, the returned function applies f to the original arguments followed by the new ones.

Takes a set of functions and returns a function that is the juxtaposition of those functions. The returned function takes any number of args and returns a vector containing the result of applying each function to the args.

Applies function f to the argument list formed by prepending any intervening arguments to args. The last argument must be a sequence.

Takes a function f and returns a function that takes the same arguments as f, has the same effects if any, and returns the opposite truth value.

Returns true if x is nil, false otherwise.

Returns true if coll has no items (its seq is nil). Works on collections, strings, and nil.

Returns true if (pred x) is logical true for every x in coll, else false.

Returns the first logical true value of (pred x) for any x in coll, else nil. Note: returns the value of (pred x), not x itself.

Returns a lazy sequence of numbers from start (inclusive) to end (exclusive), by step. With no arguments, returns an infinite sequence of natural numbers starting at 0.

Creates and returns an Atom with an initial value of x. Atoms provide a way to manage shared, synchronous, independent state with atomic compare-and-set semantics.

Atomically swaps the value of atom to be (apply f current-value-of-atom args). Returns the new value. The function f should be free of side effects, as it may be called multiple times due to retries.

Evaluates the expressions in body with the local bindings established. Bindings are a vector of name-value pairs evaluated sequentially.

Establishes local bindings and a recursion point. recur rebinds the loop variables and jumps back to the loop head, enabling efficient iteration without consuming stack.