module Indexable(T)

Overview

A container that allows accessing elements via a numeric index.

Indexing starts at 0. A negative index is assumed to be relative to the end of the container: -1 indicates the last element, -2 is the next to last element, and so on.

Types including this module are typically Array-like types.

Stability guarantees

Several methods in Indexable, such as #bsearch and #cartesian_product, require the collection to be stable; that is, calling #each(&) over and over again should always yield the same elements, provided the collection is not mutated between the calls. In particular, #each(&) itself should not mutate the collection throughout the loop. Stability of an Indexable is guaranteed if the following criteria are met:

The standard library assumes that all including types of Indexable are always stable. It is undefined behavior to implement an Indexable that is not stable or only conditionally stable.

Included Modules

Direct including types

Defined in:

lib/views/src/views/indexable_view.cr
chem/core_ext/indexable.cr

Instance Method Summary

Instance methods inherited from module Enumerable(T)

average(weights : Indexable(Number))
average(weights : Indexable(Number), & : T -> _) average, mean
mean(& : T -> _) mean

Instance Method Detail

def sentence(io : IO, separator : String = ", ", *, pair_separator : String = " and ", tail_separator : String = ", and ", & : T, IO -> ) : Nil #

Prints the elements in the collection as a sentence to io. How each element is printed is controlled by the given block.

The output depends on the number of elements in the collection:

  • If there are three or more elements, all but the tail element in the collection are joined by separator, and the tail element is joined by tail_separator.
  • If there are two elements, these are joined by pair_separator.
  • If there is one element, it is printed to io without any separator.
  • If the collection is empty, nothing is printed.
[1, 2, 3].sentence(STDOUT, "-", tail_separator: "-or-") { |e, io| io << "(#{e})" }

Prints:

(1)-(2)-or-(3)

[View source]
def sentence(io : IO, separator : String = ", ", *, pair_separator : String = " and ", tail_separator : String = ", and ") : Nil #

Prints the elements in the collection as a sentence to io.

The output depends on the number of elements in the collection:

  • If there are three or more elements, all but the tail element in the collection are joined by separator, and the tail element is joined by tail_separator.
  • If there are two elements, these are joined by pair_separator.
  • If there is one element, it is printed to io without any separator.
  • If the collection is empty, nothing is printed.
[1, 2, 3].sentence(STDOUT, "-", tail_separator: "-or-")

Prints:

1-2-or-3

[View source]
def sentence(separator : String = ", ", *, pair_separator : String = " and ", tail_separator : String = ", and ", & : T -> ) : String #

Returns a String by concatenating the elements in the collection as a sentence. How each element is printed is controlled by the given block.

The string representation depends on the number of elements in the collection:

  • If there are three or more elements, all but the tail element in the collection are joined by separator, and the tail element is joined by tail_separator.
  • If there are two elements, these are joined by pair_separator.
  • If there is one element, it is returned as is.
  • If the collection is empty, an empty string is returned.
[1, 2, 3].sentence { |e| "(#{e})" }                              # => "(1), (2), and (3)"
[1, 2, 3].sentence("-", tail_separator: "-or-") { |e| "(#{e})" } # => "(1)-(2)-or-(3)"

[View source]
def sentence(separator : String = ", ", *, pair_separator : String = " and ", tail_separator : String = ", and ") : String #

Returns a String by concatenating the elements in the collection as a sentence.

The string representation depends on the number of elements in the collection:

  • If there are three or more elements, all but the tail element in the collection are joined by separator, and the tail element is joined by tail_separator.
  • If there are two elements, these are joined by pair_separator.
  • If there is one element, it is returned as is.
  • If the collection is empty, an empty string is returned.
([] of Int32).sentence                          # => ""
[1].sentence                                    # => "1"
[1, 2].sentence                                 # => "1 and 2"
[1, 2].sentence(pair_separator: "-or-")         # => "1-or-2"
[1, 2, 3].sentence                              # => "1, 2, and 3"
[1, 2, 3].sentence("-", tail_separator: "-or-") # => "1-2-or-3"

[View source]