Sequence

Iteration and querying

first

Yields the first element.

last

Yields the last element.

take

Produces a sequence that is sub-sequence of the original one, starting from first element and of size count.

skip

Produces a sequence that is sub-sequence of the original one, containing all elements starting with the element at index count.

cut

Produces a sequence that is a sub-sequence of the original one, containing all elements starting with first and up to (but not including) the element at index size minus count. In other words, this operation returns a sequence with all elements from the original one except the last count elements.

tail

Produces a sequence that is a sub-sequence of the original one, containing all elements starting with the element at index size minus  count. In other words, this operations returns a sequence with  count  elements from the end of the original sequence, in the original order.

page

Results in a sequence that is a sub-sequence of the original one, containing all elements starting with the element at index  start  and up to (but not including) the element at index  end. It is a requirement that  start  is no greater than  end.

This is equivalent to

Where skip = start, count = end - start .

where

Produces a sequence that is a sub-sequence of the original one, with all elements for which the code passed as a parameter returns true.

ofType

Filters the sequence by the type of the elements. Returns a sub-sequence of the original one, with all elements which match the provided type. The collection is cast to the new element type.

findFirst

Results in the first element that matches the parameter closure.

findLast

Results in the last element that matches the parameter closure.

select

Results in a sequence consisting of elements, each of which is the result of applying the parameter function to each element of the original sequence in turn.

selectMany

Produces a sequence that is a concatenation of all sequences, which are all the results of applying the parameter closure to each element of the original sequence in turn. The statements  skip  and  stop  are available within the parameter closure.

distinct

Produces a sequence, which contains all elements from the original sequence in the original order, with all the elements having cardinality exactly 1. Of all occurrences of an element in the original sequence only the first occurrence is included in the resulting sequence.

sortBy

Produces a sequence with all elements from the original one in the order, which corresponds to an order induced by an imaginary sequence produced by applying the  selector  function to each element in the original sequence in turn. The  selector  function can be thought of as returning a key, which is used to sort elements in a sequence. The  ascending  parameter controls the sort order.

alsoSortBy

Equivalent to sortBy, unless used as a chain operation immediately following sortBy or another alsoSortBy. The result is a sequence sorted with a compound key, with the first component taken from previous sortBy or alsoSortBy (which is also a compound key), and the last component taken from this operation.

sort

Produces a sequence containing all elements from the original one in the order produced by applying the  comparator  function (passed as a closure literal or by reference) to a list with elements from the original sequence. The  ascending  parameter controls the sort order (order is reversed if the value is false).

intersect

Produces a sequence containing elements contained both by the original sequence and the parameter sequence. More precisely, the cardinality in the output of an element appearing in both the operand and the parameter sequences, is the minimum of its cardinalities in the input. 

except

Produces a sequence containing all elements from the original sequence that are not also members of the parameter sequence. More precisely, the cardinality in the output of an element appearing in both the operand and the parameter sequences, is the maximum of 0 and the result of subtracting the parameter's cardinality from the operand's cardinality. 

union

Produces a sequence containing elements either from the original sequence or the one passed as a parameter. More precisely, the cardinality in the output of an element appearing in both the operand and the parameter sequences, is the maximum of its cardinalities in the input. 

disjunction

Produces exclusive disjunction (symmetric difference) of the original sequence and the one passed as a parameter. This operation equivalent to:

reduceLeft / reduceRight

Operation reduceLeft/reduceRight applies the combinator function passed as a parameter to all elements of the sequence in turn. One of the function parameters is a sequence element, and another is the result of previous application of the function. Operation reduceLeft takes first two sequence elements and applies the function to them, then takes the result of the first application and the third sequence element, etc. Operation reduceRight does the same, but moving from the sequence's tail backwards.

• reduceLeft

• reduceRight

foldLeft / foldRight

Operation foldLeft/foldRight behaves similarly to reduceLeft/reduceRight, with the difference that it also accepts a seed value. Also the combinator function is asymmetric (it takes a Type and a Z parameters and returns a Z value). The result of the operation is of type Z.

• foldLeft

• foldRight

join

This operation is only available on a sequence of strings. The result is a string that is produced by concatenating all elements with the optional separator. The default separator is " " (single space).

toList

Returns new list containing all the elements from the original sequence.

toArray

Returns new array containing all the elements from the original sequence.