iter f e calls the function f with each elements of e in turn.

iter2 f e1 e2 calls the function f with the next elements of e and e2 repeatedly until one of the two enumerations ends.

fold f v e returns v if e is empty, otherwise f aN (... (f a2 (f a1 v)) ...) where a1..N are the elements of e.

fold2 is similar to fold but will fold over two enumerations at the same time until one of the two enumerations ends.

find f e returns the first element x of e such that f x returns true, consuming the enumeration up to and including the found element, or, raises Not_found if no such element exists in the enumeration, consuming the whole enumeration in the search.

Since find consumes a prefix of the enumeration, it can be used several times on the same enumeration to find the next element.

is_empty e returns true if e does not contains any element.

peek e returns None if e is empty or Some x where x is the next element of e. The element is not removed from the enumeration.

get e returns None if e is empty or Some x where x is the next element of e, in which case the element is removed from the enumeration.

next e returns the next element of e (and removes it from enumeration).

• raises No_more_elements

  if enumeration is empty

push e x will add x at the beginning of e.

junk e removes the first element from the enumeration, if any.

clone e creates a new enumeration that is copy of e. If e is consumed by later operations, the clone will not get affected.

force e forces the application of all lazy functions and the enumeration of all elements, exhausting the enumeration.

An efficient intermediate data structure of enumerated elements is constructed and e will now enumerate over that data structure.

map f e returns an enumeration over (f a1, f a2, ... , f aN) where a1...N are the elements of e.

mapi is similar to map except that f is passed one extra argument which is the index of the element in the enumeration, starting from 0.

filter f e returns an enumeration over all elements x of e such as f x returns true.

filter_map f e returns an enumeration over all elements x such as f y returns Some x , where y is an element of e.

append e1 e2 returns an enumeration that will enumerate over all elements of e1 followed by all elements of e2.

concat e returns an enumeration over all elements of all enumerations of e.

This exception shall be raised by the next function of make or from when no more elements can be enumerated, it shall not be raised by any function which is an argument to any other function specified in the interface.

The empty enumeration : contains no element

This function creates a fully defined enumeration.

• the next function shall return the next element of the enumeration or raise No_more_elements if the underlying data structure does not have any more elements to enumerate.
• the count function shall return the actual number of remaining elements in the enumeration.
• the clone function shall create a clone of the enumeration such as operations on the original enumeration will not affect the clone.

For some samples on how to correctly use make, you can have a look at implementation of ExtList.enum.

from next creates an enumeration from the next function. next shall return the next element of the enumeration or raise No_more_elements when no more elements can be enumerated. Since the enumeration definition is incomplete, a call to clone or count will result in a call to force that will enumerate all elements in order to return a correct value.

init n f creates a new enumeration over elements f 0, f 1, ..., f (n-1)

count e returns the number of remaining elements in e without consuming the enumeration.

Depending of the underlying data structure that is implementing the enumeration functions, the count operation can be costly, and even sometimes can cause a call to force.

For users worried about the speed of count you can call the fast_count function that will give an hint about count implementation. Basically, if the enumeration has been created with make or init or if force has been called on it, then fast_count will return true.