F# Collections

-------------- module array ------------ [array](https://github.com/sudipto80/fscollections/blob/master/array.md)

Function	Description
append	Creates an array that contains the elements of one array followed by the elements of another array.
average	Returns the average of the elements in an array.
averageBy	Returns the average of the elements generated by applying a function to each element of an array.
blit	Reads a range of elements from one array and writes them into another.
choose	Applies a supplied function to each element of an array. Returns an array that contains the results x for each element for which the function returns Some(x) .
collect	Applies the supplied function to each element of an array, concatenates the results, and returns the combined array.
concat	Creates an array that contains the elements of each of the supplied sequence of arrays.
copy	Creates an array that contains the elements of the supplied array.
create	Creates an array whose elements are all initially the supplied value.
exists	Tests whether any element of an array satisfies the supplied predicate.
exists2	Tests whether any pair of corresponding elements of two arrays satisfy the supplied condition.
fill	Fills a range of elements of an array with the supplied value.
filter	Returns a collection that contains only the elements of the supplied array for which the supplied condition returns true .
find	Returns the first element for which the supplied function returns true . Raises KeyNotFoundException if no such element exists.
findIndex	Returns the index of the first element in an array that satisfies the supplied condition. Raises KeyNotFoundException if none of the elements satisfy the condition.
fold	Applies a function to each element of an array, threading an accumulator argument through the computation. If the input function is f and the array elements are i0...iN , this function computes f (...(f s i0)...) iN .
fold2	Applies a function to pairs of elements from two supplied arrays, left-to-right, threading an accumulator argument through the computation. The two input arrays must have the same lengths; otherwise, ArgumentException is raised.
foldBack	Applies a function to each element of an array, threading an accumulator argument through the computation. If the input function is f and the array elements are i0...iN , this function computes f i0 (...(f iN s)) .
foldBack2	Applies a function to pairs of elements from two supplied arrays, right-to-left, threading an accumulator argument through the computation. The two input arrays must have the same lengths; otherwise, ArgumentException is raised.
forall	Tests whether all elements of an array satisfy the supplied condition.
get	Gets an element from an array.
isEmpty	Tests whether an array has any elements.
iter	Applies the supplied function to each element of an array.
iter2	Applies the supplied function to a pair of elements from matching indexes in two arrays. The two arrays must have the same lengths; otherwise, ArgumentException is raised.
iteri	Applies the supplied function to each element of an array. The integer passed to the function indicates the index of the element.
iteri2	Applies the supplied function to a pair of elements from matching indexes in two arrays, also passing the index of the elements. The two arrays must have the same lengths; otherwise, an ArgumentException is raised.
length	Returns the length of an array. The Length property does the same thing.
map	Creates an array whose elements are the results of applying the supplied function to each of the elements of a supplied array.
map2	Creates an array whose elements are the results of applying the supplied function to the corresponding elements of two supplied arrays. The two input arrays must have the same lengths; otherwise, ArgumentException is raised.
mapi	Creates an array whose elements are the results of applying the supplied function to each of the elements of a supplied array. An integer index passed to the function indicates the index of the element being transformed.
mapi2	Creates an array whose elements are the results of applying the supplied function to the corresponding elements of the two collections pairwise, also passing the index of the elements. The two input arrays must have the same lengths; otherwise, ArgumentException is raised.
max	Returns the largest of all elements of an array. Operators.max is used to compare the elements.
maxBy	Returns the largest of all elements of an array, compared via Operators.max on the function result.
min	Returns the smallest of all elements of an array. Operators.min is used to compare the elements.
minBy	Returns the smallest of all elements of an array. Operators.min is used to compare the elements.
ofList	Creates an array from the supplied list.
ofSeq	Creates an array from the supplied enumerable object.
partition	Splits an array into two arrays, one containing the elements for which the supplied condition returns true , and the other containing those for which it returns false .
permute	Permutes the elements of an array according to the specified permutation.
pick	Applies the supplied function to successive elements of a supplied array, returning the first result where the function returns Some(x) for some x . If the function never returns Some(x) , KeyNotFoundException is raised.
reduce	Applies a function to each element of an array, threading an accumulator argument through the computation. If the input function is f and the array elements are i0...iN , this function computes f (...(f i0 i1)...) iN . If the array has size zero, ArgumentException is raised.
reduceBack	Applies a function to each element of an array, threading an accumulator argument through the computation. If the input function is f and the elements are i0...iN , this function computes f i0 (...(f iN-1 iN)) . If the array has size zero, ArgumentException is raised.
rev	Reverses the order of the elements in a supplied array.
scan	Behaves like fold , but returns the intermediate results together with the final results.
scanBack	Behaves like foldBack , but returns the intermediary results together with the final results.
set	Sets an element of an array.
sort	Sorts the elements of an array and returns a new array. Operators.compare is used to compare the elements.
sortBy	Sorts the elements of an array by using the supplied function to transform the elements to the type on which the sort operation is based, and returns a new array. Operators.compare is used to compare the elements.
sortInPlace	Sorts the elements of an array by changing the array in place, using the supplied comparison function. Operators.compare is used to compare the elements.
sortInPlaceBy	Sorts the elements of an array by changing the array in place, using the supplied projection for the keys. Operators.compare is used to compare the elements.
sortInPlaceWith	Sorts the elements of an array by using the supplied comparison function to change the array in place.
sortWith	Sorts the elements of an array by using the supplied comparison function, and returns a new array.
sub	Creates an array that contains the supplied subrange, which is specified by starting index and length.
sum	Returns the sum of the elements in the array.
sumBy	Returns the sum of the results generated by applying a function to each element of an array.
toList	Converts the supplied array to a list.
tryFind	Returns the first element in the supplied array for which the supplied function returns true . Returns None if no such element exists.
tryFindIndex	Returns the index of the first element in an array that satisfies the supplied condition.
tryPick	Applies the supplied function to successive elements of the supplied array, and returns the first result where the function returns Some(x) for some x . If the function never returns Some(x) , None is returned.
unzip	Splits an array of tuple pairs into a tuple of two arrays.
unzip3	Splits an array of tuples of three elements into a tuple of three arrays.
zeroCreate	Creates an array whose elements are initially set to the default value Unchecked.defaultof<'T> .
zip	Combines two arrays into an array of tuples that have two elements. The two arrays must have equal lengths; otherwise, ArgumentException is raised.
zip3	Combines three arrays into an array of tuples that have three elements. The three arrays must have equal lengths; otherwise, ArgumentException is raised.

list

Function	Description
append	Returns a new list that contains the elements of the first list followed by elements of the second.
average	Returns the average of the elements in the list.
averageBy	Returns the average of the elements generated by applying the function to each element of the list.
choose	Applies the given function to each element of the list. Returns the list comprised of the results for each element where the function returns Some .
collect	For each element of the list, applies the given function. Concatenates all the results and return the combined list.
concat	Returns a new list that contains the elements of each the lists in order.
exists	Tests if any element of the list satisfies the given predicate.
exists2	Tests if any pair of corresponding elements of the lists satisfies the given predicate.
filter	Returns a new collection containing only the elements of the collection for which the given predicate returns true .
find	Returns the first element for which the given function returns true .
findIndex	Returns the index of the first element in the list that satisfies the given predicate.
fold	Applies a function to each element of the collection, threading an accumulator argument through the computation. This function takes the second argument, and applies the function to it and the first element of the list. Then, it passes this result into the function along with the second element, and so on. Finally, it returns the final result. If the input function is f and the elements are i0...iN , then this function computes f (... (f s i0) i1 ...) iN .
fold2	Applies a function to corresponding elements of two collections, threading an accumulator argument through the computation. The collections must have identical sizes. If the input function is f and the elements are i0...iN and j0...jN , then this function computes f (... (f s i0 j0)...) iN jN .
foldBack	Applies a function to each element of the collection, threading an accumulator argument through the computation. If the input function is f and the elements are i0...iN then computes f i0 (...(f iN s)) .
foldBack2	Applies a function to corresponding elements of two collections, threading an accumulator argument through the computation. The collections must have identical sizes. If the input function is f and the elements are i0...iN and j0...jN , then this function computes f i0 j0 (...(f iN jN s)) .
forall	Tests if all elements of the collection satisfy the given predicate.
forall2	Tests if all corresponding elements of the collection satisfy the given predicate pairwise.
init	Creates a list by calling the given generator on each index.
isEmpty	Returns true if the list contains no elements, false otherwise.
iter	Applies the given function to each element of the collection.
iter2	Applies the given function to two collections simultaneously. The collections must have identical size.
iteri	Applies the given function to each element of the collection. The integer passed to the function indicates the index of element.
iteri2	Applies the given function to two collections simultaneously. The collections must have identical size. The integer passed to the function indicates the index of element.
length	Returns the length of the list.
map	Creates a new collection whose elements are the results of applying the given function to each of the elements of the collection.
map2	Creates a new collection whose elements are the results of applying the given function to the corresponding elements of the two collections pairwise.
map3	Creates a new collection whose elements are the results of applying the given function to the corresponding elements of the three collections simultaneously.
mapi	Creates a new collection whose elements are the results of applying the given function to each of the elements of the collection. The integer index passed to the function indicates the index (from 0) of element being transformed.
mapi2	Like List.mapi , but mapping corresponding elements from two lists of equal length.
max	Return the greatest of all elements of the list, compared by using Operators.max .
maxBy	Returns the greatest of all elements of the list, compared by using Operators.max on the function result.
min	Returns the lowest of all elements of the list, compared by using Operators.min .
minBy	Returns the lowest of all elements of the list, compared by using Operators.min on the function result
ofArray	Creates a list from the given array.
ofSeq	Creates a new list from the given enumerable object.
partition	Splits the collection into two collections, containing the elements for which the given predicate returns true and false respectively.
permute	Returns a list with all elements permuted according to the specified permutation.
pick	Applies the given function to successive elements, returning the first result where function returns Some for some value.
reduce	Applies a function to each element of the collection, threading an accumulator argument through the computation. This function applies the specified function to the first two elements of the list. It then passes this result into the function along with the third element, and so on. Finally, it returns the final result. If the input function is f and the elements are i0...iN , then this function computes f (... (f i0 i1) i2 ...) iN .
reduceBack	Applies a function to each element of the collection, threading an accumulator argument through the computation. If the input function is f and the elements are i0...iN , then this function computes f i0 (...(f iN-1 iN)) .
replicate	Creates a list by calling the given generator on each index.
rev	Returns a new list with the elements in reverse order.
scan	Applies a function to each element of the collection, threading an accumulator argument through the computation. This function takes the second argument, and applies the specified function to it and the first element of the list. Then, it passes this result into the function along with the second element and so on. Finally, it returns the list of intermediate results and the final result.
scanBack	Like foldBack , but returns both the intermediate and final results
sort	Sorts the given list using Operators.compare .
sortBy	Sorts the given list using keys given by the given projection. Keys are compared using Operators.compare .
sortWith	Sorts the given list using the given comparison function.
sumBy	Returns the sum of the results generated by applying the function to each element of the list.
tail	Returns the input list without the first element.
toArray	Creates an array from the given list.
toSeq	Views the given list as a sequence.
tryFind	Returns the first element for which the given function returns true . Return None if no such element exists.
tryFindIndex	Returns the index of the first element in the list that satisfies the given predicate. Return None if no such element exists.
tryPick	Applies the given function to successive elements, returning the first result where function returns Some for some value. If no such element exists then return None .
unzip	Splits a list of pairs into two lists.
unzip3	Splits a list of triples into three lists.
zip	Combines the two lists into a list of pairs. The two lists must have equal lengths.
zip3	Combines the three lists into a list of triples. The lists must have equal lengths.

seq

Function	Description
append	Wraps the two given enumerations as a single concatenated enumeration.
average	Returns the average of the elements in the sequence.
averageBy	Returns the average of the results generated by applying the function to each element of the sequence.
cache	Returns a sequence that corresponds to a cached version of the input sequence.
cast	Wraps a loosely-typed System.Collections sequence as a typed sequence.
choose	Applies the given function to each element of the list. Return the list comprised of the results for each element where the function returns Some .
collect	Applies the given function to each element of the sequence and concatenates all the results.
compareWith	Compares two sequences using the given comparison function, element by element.
concat	Combines the given enumeration-of-enumerations as a single concatenated enumeration.
countBy	Applies a key-generating function to each element of a sequence and return a sequence yielding unique keys and their number of occurrences in the original sequence.
delay	Returns a sequence that is built from the given delayed specification of a sequence.
distinct	Returns a sequence that contains no duplicate entries according to generic hash and equality comparisons on the entries. If an element occurs multiple times in the sequence then the later occurrences are discarded.
distinctBy	Returns a sequence that contains no duplicate entries according to the generic hash and equality comparisons on the keys returned by the given key-generating function. If an element occurs multiple times in the sequence then the later occurrences are discarded.
exactlyOne	Returns the only element of the sequence.
exists	Tests if any element of the sequence satisfies the given predicate.
exists2	Tests if any pair of corresponding elements of the input sequences satisfies the given predicate.
filter	Returns a new collection containing only the elements of the collection for which the given predicate returns true .
find	Returns the first element for which the given function returns true .
findIndex	Returns the index of the first element for which the given function returns true .
fold	Applies a function to each element of the collection, threading an accumulator argument through the computation. If the input function is f and the elements are i0...iN, then this function computes f (... (f s i0)...) iN .
forall	Tests if all elements of the sequence satisfy the given predicate.
forall2	Tests the all pairs of elements drawn from the two sequences satisfy the given predicate. If one sequence is shorter than the other then the remaining elements of the longer sequence are ignored.
groupBy	Applies a key-generating function to each element of a sequence and yields a sequence of unique keys. Each unique key has also contains a sequence of all elements that match to this key.
head	Returns the first element of the sequence.
init	Generates a new sequence which, when iterated, returns successive elements by calling the given function, up to the given count. The results of calling the function are not saved, that is, the function is reapplied as necessary to regenerate the elements. The function is passed the index of the item being generated.
initInfinite	Generates a new sequence which, when iterated, will return successive elements by calling the given function. The results of calling the function are not saved, that is, the function will be reapplied as necessary to regenerate the elements. The function is passed the index of the item being generated.
isEmpty	Tests whether a sequence has any elements.
iter	Applies the given function to each element of the collection.
iteri	Applies the given function to each element of the collection. The integer passed to the function indicates the index of element.
iter2	Applies the given function to two collections simultaneously. If one sequence is shorter than the other then the remaining elements of the longer sequence are ignored.
last	Returns the last element of the sequence.
length	Returns the length of the sequence.
map	Creates a new collection whose elements are the results of applying the given function to each of the elements of the collection. The given function will be applied as elements are demanded using the MoveNext method on enumerators retrieved from the object.
mapi	Creates a new collection whose elements are the results of applying the given function to each of the elements of the collection. The integer index passed to the function indicates the index (from 0) of element being transformed.
map2	Creates a new collection whose elements are the results of applying the given function to the corresponding pairs of elements from the two sequences. If one input sequence is shorter than the other then the remaining elements of the longer sequence are ignored.
max	Returns the greatest of all elements of the sequence, compared by using Operators.max .
maxBy	Returns the greatest of all elements of the sequence, compared by using Operators.max on the function result.
min	Returns the lowest of all elements of the sequence, compared by using Operators.min .
minBy	Returns the lowest of all elements of the sequence, compared by using Operators.min on the function result.
nth	Computes the nth element in the collection.
ofArray	Views the given array as a sequence.
ofList	Views the given list as a sequence.
pairwise	Returns a sequence of each element in the input sequence and its predecessor, with the exception of the first element which is only returned as the predecessor of the second element.
pick	Applies the given function to successive elements, returning the first value where the function returns a Some value.
readonly	Creates a new sequence object that delegates to the given sequence object. This ensures the original sequence cannot be rediscovered and mutated by a type cast. For example, if given an array the returned sequence will return the elements of the array, but you cannot cast the returned sequence object to an array.
reduce	Applies a function to each element of the sequence, threading an accumulator argument through the computation. Begin by applying the function to the first two elements. Then feed this result into the function along with the third element and so on. Return the final result.
scan	Like Seq.fold , but computes on-demand and returns the sequence of intermediary and final results.
singleton	Returns a sequence that yields one item only.
skip	Returns a sequence that skips a specified number of elements of the underlying sequence and then yields the remaining elements of the sequence.
skipWhile	Returns a sequence that, when iterated, skips elements of the underlying sequence while the given predicate returns true , and then yields the remaining elements of the sequence.
sort	Yields a sequence ordered by keys.
sum	Returns the sum of the elements in the sequence.
sumBy	take
take	Returns the first elements of the sequence up to a specified count.
takeWhile	Returns a sequence that, when iterated, yields elements of the underlying sequence while the given predicate returns true , and then returns no further elements.
toArray	Creates an array from the given collection.
toList	Creates a list from the given collection.
tryFind	Returns the first element for which the given function returns true , or None if no such element exists.
tryFindIndex	Returns the index of the first element in the sequence that satisfies the given predicate, or None if no such element exists.
tryPick	Applies the given function to successive elements, returning the first value where the function returns a Some value.
truncate	Returns a sequence that when enumerated returns no more than a specified number of elements.
unfold	Returns a sequence that contains the elements generated by the given computation.
where	Returns a new collection containing only the elements of the collection for which the given predicate returns true . A synonym for Seq.filter .
windowed	Returns a sequence that yields sliding windows of containing elements drawn from the input sequence. Each window is returned as a fresh array.
zip	Combines the two sequences into a list of pairs. The two sequences need not have equal lengths: when one sequence is exhausted any remaining elements in the other sequence are ignored.
zip3	Combines the three sequences into a list of triples. The sequences need not have equal lengths: when one sequence is exhausted any remaining elements in the other sequences are ignored.

map

Function	Description
add	Returns a new map with the binding added to the given map.
containsKey	Tests if an element is in the domain of the map.
exists	Returns true if the given predicate returns true for one of the bindings in the map.
filter	Creates a new map containing only the bindings for which the given predicate returns true .
find	Looks up an element in the map.
findKey	Evaluates the function on each mapping in the collection. Returns the key for the first mapping where the function returns true .
fold	Folds over the bindings in the map
foldBack	Folds over the bindings in the map.
forall	Returns true if the given predicate returns true for all of the bindings in the map.
isEmpty	Tests whether the map has any bindings.
iter	Applies the given function to each binding in the dictionary
map	Creates a new collection whose elements are the results of applying the given function to each of the elements of the collection. The key passed to the function indicates the key of element being transformed.
ofArray	Returns a new map made from the given bindings.
ofList	Returns a new map made from the given bindings.
ofSeq	Returns a new map made from the given bindings.
partition	Creates two new maps, one containing the bindings for which the given predicate returns true , and the other the remaining bindings.
pick	Searches the map looking for the first element where the given function returns a Some value
remove	Removes an element from the domain of the map. No exception is raised if the element is not present.
toArray	Returns an array of all key/value pairs in the mapping. The array will be ordered by the keys of the map.
toList	Returns a list of all key/value pairs in the mapping. The list will be ordered by the keys of the map.
toSeq	Views the collection as an enumerable sequence of pairs. The sequence will be ordered by the keys of the map.
tryFind	Looks up an element in the map, returning a Some value if the element is in the domain of the map, or None if not.
tryFindKey	Returns the key of the first mapping in the collection that satisfies the given predicate, or returns None if no such element exists.
tryPick	Searches the map looking for the first element where the given function returns a Some value.

set

Function	Description
add	Returns a new set with an element added to the set. No exception is raised if the set already contains the given element.
contains	Evaluates to true if the given element is in the given set.
count	Returns the number of elements in the set.
difference	Returns a new set with the elements of the second set removed from the first.
exists	Tests if any element of the collection satisfies the given predicate. If the input function is predicate and the elements are i0...iN , then this function computes predicate i0 or ... or predicate iN .
filter	Returns a new collection containing only the elements of the collection for which the given predicate returns true .
fold	Applies the given accumulating function to all the elements of the set
foldBack	Applies the given accumulating function to all the elements of the set.
forall	Tests if all elements of the collection satisfy the given predicate. If the input function is p and the elements are i0...iN, then this function computes p i0 && ... && p iN .
intersect	Computes the intersection of the two sets.
intersectMany	Computes the intersection of a sequence of sets. The sequence must be non-empty.
isEmpty	Returns true if the set is empty.
isProperSubset	Evaluates to true if all elements of the first set are in the second, and at least one element of the second is not in the first.
isProperSuperset	Evaluates to true if all elements of the second set are in the first, and at least one element of the first is not in the second.
isSubset	Evaluates to true if all elements of the first set are in the second
isSuperset	Evaluates to true if all elements of the second set are in the first.
iter	Applies the given function to each element of the set, in order according to the comparison function.
map	Returns a new collection containing the results of applying the given function to each element of the input set.
maxElement	Returns the highest element in the set according to the ordering being used for the set.
minElement	Returns the lowest element in the set according to the ordering being used for the set.
ofArray	Creates a set that contains the same elements as the given array.
ofList	Creates a set that contains the same elements as the given list.
ofSeq	Creates a new collection from the given enumerable object.
partition	Splits the set into two sets containing the elements for which the given predicate returns true and false respectively.
remove	Returns a new set with the given element removed. No exception is raised if the set doesn't contain the given element.
singleton	The set containing the given element.
toArray	Creates an array that contains the elements of the set in order.
toSeq	Returns an ordered view of the collection as an enumerable object.
union	Computes the union of the two sets.
unionMany	Computes the union of a sequence of sets.