Filter an array so that duplicate items are removed

1-byte built-ins

05AB1E (legacy)

Ù

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Alternatively:

ê

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APL (Dyalog Unicode)

∪

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Jelly

Q

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W

U

Stax

u

MATL

u

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MathGolf

▀

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Seriously/Actually

╔

Japt

â

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Pyth

{

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Husk

u

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Pyke

}

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Canvas

Ｄ

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Python 3, ¹⁵ 3 bytes

Reduced to 3 bytes thanks to a'_'!!!

set

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Without set

Python 3, ^{35 \$\cdots\$30} 29 bytes

Saved 3 bytes thanks to a'_'!!!
Saved a byte thanks to Jitse!!!
Saved a byte thanks to Jonathan Allan!!!

lambda l:list(dict(zip(l,l)))

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Python 3, 3 bytes

set

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Or without set:

Python 3, 34 29 26 bytes

lambda l:[*dict(zip(l,l))]

Try it online! Thanks to Jonathan Alan and Surculose Sputum for helping me golf this one!