Comparison of programming languages (associative array): Difference between revisions

Revision as of 23:07, 31 July 2020

Revision as of 23:14, 31 July 2020

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This returns an <code>Option</code> type, Scala's equivalent of the [[Monad (functional programming)#The Maybe monad|Maybe monad]] in Haskell.

=== [[Smalltalk]] ===

In [[Smalltalk]] a dictionary<code>Dictionary</code> is used:

<syntaxhighlight lang=Smalltalk>

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</syntaxhighlight>

To access an entry the message <code>#at:</code> is sent to the dictionary object.:

<syntaxhighlight lang=Smalltalk>

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</syntaxhighlight>

Which gives:

<syntaxhighlight lang=Text>

'555-9999'

</syntaxhighlight>

DictionaryA dictionary hashes/, or compares, based on equality and holdsmarks both key and value as

[[Garbage collection (computer science)#Strong and weak references|strong references]] to both key and value. Variants exist in which hash/compare on identity (IdentityDictionary) or keep [[Garbage collection (computer science)#Strong and weak references|weak references]] (WeakKeyDictionary / WeakValueDictionary).

Because every object implements #hash, any object can be used as key (and of course also as value).