elt

It allows access to individual elements through an integer index.

length

It returns the length of a sequence.

subseq

It returns a sub-sequence by extracting the subsequence starting at a particular index and continuing to a particular ending index or the end of the sequence.

copy-seq

It returns a sequence that contains the same elements as its argument.

fill

It is used to set multiple elements of a sequence to a single value.

replace

It takes two sequences and the first argument sequence is destructively modified by copying successive elements into it from the second argument sequence.

count

It takes an item and a sequence and returns the number of times the item appears in the sequence.

reverse

It returns a sequence contains the same elements of the argument but in reverse order.

nreverse

It returns the same sequence containing the same elements as sequence but in reverse order.

concatenate

It creates a new sequence containing the concatenation of any number of sequences.

position

It takes an item and a sequence and returns the index of the item in the sequence or nil.

find

It takes an item and a sequence. It finds the item in the sequence and returns it, if not found then it returns nil.

sort

It takes a sequence and a two-argument predicate and returns a sorted version of the sequence.

merge

It takes two sequences and a predicate and returns a sequence produced by merging the two sequences, according to the predicate.

map

It takes an n-argument function and n sequences and returns a new sequence containing the result of applying the function to subsequent elements of the sequences.

some

It takes a predicate as an argument and iterates over the argument sequence, and returns the first non-NIL value returned by the predicate or returns false if the predicate is never satisfied.

every

It takes a predicate as an argument and iterate over the argument sequence, it terminates, returning false, as soon as the predicate fails. If the predicate is always satisfied, it returns true.

notany

It takes a predicate as an argument and iterate over the argument sequence, and returns false as soon as the predicate is satisfied or true if it never is.

notevery

It takes a predicate as an argument and iterate over the argument sequence, and returns true as soon as the predicate fails or false if the predicate is always satisfied.

reduce

It maps over a single sequence, applying a two-argument function first to the first two elements of the sequence and then to the value returned by the function and subsequent elements of the sequence.

search

It searches a sequence to locate one or more elements satisfying some test.

remove

It takes an item and a sequence and returns the sequence with instances of item removed.

delete

This also takes an item and a sequence and returns a sequence of the same kind as the argument sequence that has the same elements except the item.

substitute

It takes a new item, an existing item, and a sequence and returns a sequence with instances of the existing item replaced with the new item.

nsubstitute

It takes a new item, an existing item, and a sequence and returns the same sequence with instances of the existing item replaced with the new item.

mismatch

It takes two sequences and returns the index of the first pair of mismatched elements.