# \[Pitch #3\] Introduce user-defined dynamically "callable" types

**URL:** <https://forums.swift.org/t/pitch-3-introduce-user-defined-dynamically-callable-types/12232>\
**Category:** Pitches\
**Created:** [April 28, 2018, 10:42pm UTC](https://forums.swift.org/t/pitch-3-introduce-user-defined-dynamically-callable-types/12232 "2018-04-28T22:42:20Z")\
**Posts on this page:** 1\
**Showing post:** 54

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**Author:** ![masters3d](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@masters3d](https://forums.swift.org/u/masters3d)\
**Post date:** [May 2, 2018, 7:46pm UTC](https://forums.swift.org/t/pitch-3-introduce-user-defined-dynamically-callable-types/12232/54 "2018-05-02T19:46:36Z")

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The proposal is using DictionaryLiteral which allows duplicate keys. Its is a weird type. [Further discussion about it.](https://forums.swift.org/t/100-bikeshed-topic-dictionaryliteral/7385/2)

```nohighlight
func justPrinting<T>( _ input: DictionaryLiteral<String, T>)
{
    print(input)
}

justPrinting(["": 1, "": 2, "": 3]) // DictionaryLiteral<String, Int>(_elements: [("", 1), ("", 2), ("", 3)])

```

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