frost.collections

Interface CollectionView<T>

Implemented Interfaces:
Iterable<T>

A read-only view of a collection of elements. A CollectionView's elements are accessed via its iterator property.

See also:
CollectionWriter
Collection
ListView
Source Code:
View Source

Field Summary

count:Int
The number of elements in the collection.
first:T
Returns the first element in the collection in iteration order.
Inherited Fields:
toString

Instance Method Summary

join():String
Returns the string concatenation of all of the items in this collection, in iteration order.
join(separator:String):String
Converts all of the items in this collection to strings and concatenates them in iteration order, with the given separator between them.
fold(f:(T, T)=>(T)):T
Successively applies a binary function to 'fold' the elements in the list down to a single value.
fold(f:(T, T)=&>(T)):T
As fold((T, T)=>(T)), but for methods instead of functions.
fold(f:(T, T)=>(T), start:T):T
As fold((T, T)=>(T)), but additionally takes a starting value for the fold operation.
fold(f:(T, T)=&>(T), start:T):T
As fold((T, T)=>(T), T), but for methods instead of functions.
apply(m:(T)=&>())
Calls the method m on each element of the collection in iteration order.
map<U>(f:(T)=>(U)):Array<U>
Returns an array containing the result of calling f on every element in this collection.
map<U>(f:(T)=&>(U)):Array<U>
As map((T)=>(U)), but for methods instead of functions.

Fields

property count:Int

The number of elements in the collection.

property first:T

Returns the first element in the collection in iteration order.

Instance Methods

@default
function join ():String

Returns the string concatenation of all of the items in this collection, in iteration order. Equivalent to join("").

See also:
join(String)
@default
function join (separator:String
):String

Converts all of the items in this collection to strings and concatenates them in iteration order, with the given separator between them. For instance, [1, 2, 3].join("|") returns "1|2|3".

Parameters:
separator - the delimiter string
See also:
join()
@default
@pre(count > 0)
function fold (f:(T, T)=>(T)
):T

Successively applies a binary function to 'fold' the elements in the list down to a single value. For instance, if we have a collection of Int64s and fold using the binary function Int64.+(Int64), as in:

[1, 2, 3, 4, 5].fold(Int.+)
Try it!

this would add the first (in iteration order) and second elements of the collection together, and then add the sum of the first two elements to the third, and so forth until all of the elements of the collection had been added together. This would result in the sum of all of the elements in the collection.

Similarly, we could fold using Int64.max(Int64) to find the biggest number in the list, Int64.*(Int64) to get the product of all of the numbers in the list, etc.

If the list has only a single element in the list, the result of fold is this single element and the function f is never called. This variant of fold may not be called on an empty list because the result would be undefined.

Parameters:
f - a binary function to combine elements of the collection
Returns:
the result of combining the entire collection
See also:
fold((T, T)=>(T), T)
@default
@pre(count > 0)
method fold (f:(T, T)=&>(T)
):T

As fold((T, T)=>(T)), but for methods instead of functions.

Parameters:
f - value of type (T, T)=&>(T)
@default
function fold (f:(T, T)=>(T),
 start:T
):T

As fold((T, T)=>(T)), but additionally takes a starting value for the fold operation. The starting value is folded into the first element of the list, the result is then folded into the second element, etc. This allows fold to be well-defined even on an empty list: folding an empty list simply returns the start value.

Parameters:
f - a binary function to combine elements of the collection
start - the starting value for the fold
See also:
fold((T, T)=>(T))
@default
method fold (f:(T, T)=&>(T),
 start:T
):T

As fold((T, T)=>(T), T), but for methods instead of functions.

Parameters:
f - value of type (T, T)=&>(T)
start - value of type T
@default
method apply (m:(T)=&>())

Calls the method m on each element of the collection in iteration order. For instance, to display every element in a collection you could write:

collection.apply(Console.printLine)
Try it!
Parameters:
m - a method to call on each element
@default
function map<U> (f:(T)=>(U)
):Array<U>

Returns an array containing the result of calling f on every element in this collection. For example,

Console.printLine(Int[1 ... 5].map(2.*))
Try it!

applies the function 2.* to the integers from 1 to 5. This displays [2, 4, 6, 8, 10].

Parameters:
f - value of type (T)=>(U)
@default
method map<U> (f:(T)=&>(U)
):Array<U>

As map((T)=>(U)), but for methods instead of functions.

Parameters:
f - value of type (T)=&>(U)