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

Revision as of 18:24, 9 August 2025

Latest revision as of 08:42, 13 August 2025

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===F#===

===={{code|Map<'Key,'Value>}}====

At runtime, [[F Sharp (programming language)|F#]] provides the <code>Collections.Map<'Key,'Value></code> type, which is an immutable [[AVL tree]].

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=====Access by key=====

Values can be looked up via one of the <code>Map</code> members, such as its indexer or <code>Item</code> property (which throw an [[Exception handling|exception]] if the key does not exist) or the <code>TryFind</code> function, which returns an [[option type]] with a value of <{{code>|Some <result></code>|f#}}, for a successful lookup, or <code>None</code>, for an unsuccessful one. [[Pattern matching]] can then be used to extract the raw value from the result, or a default value can be set.

<syntaxhighlight lang="fsharp">

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In both examples above, the <code>sallyNumber</code> value would contain the string <code>"555-9999"</code>.

===={{code|Dictionary<'TKey,'TValue>}}====

Because F# is a .NET language, it also has access to features of the [[.NET Framework]], including the {{code|System.Collections.Generic.Dictionary<'TKey,'TValue>|f#}} type (which is implemented as a [[hash table]]), which is the primary associative array type used in C# and Visual Basic. This type may be preferred when writing code that is intended to operate with other languages on the .NET Framework, or when the performance characteristics of a hash table are preferred over those of an AVL tree.

=====Creation=====

The <code>dict</code> function provides a means of conveniently creating a .NET dictionary that is not intended to be mutated; it accepts a sequence of tuples and returns an immutable object that implements <{{code>|IDictionary<'TKey,'TValue></code>|f#}}.

<syntaxhighlight lang="fsharp">