# What's @\_transparent for?

**URL:** <https://forums.swift.org/t/whats-transparent-for/38154>\
**Category:** Standard Library\
**Created:** [July 3, 2020, 6:23pm UTC](https://forums.swift.org/t/whats-transparent-for/38154 "2020-07-03T18:23:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![wowbagger](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/wowbagger/32/13847_2.png) [@wowbagger](https://forums.swift.org/u/wowbagger)\
**Post date:** [July 3, 2020, 6:23pm UTC](https://forums.swift.org/t/whats-transparent-for/38154/1 "2020-07-03T18:23:52Z")

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Also, is there a list of attributes used in the standard library, much like the one in _The Swift Programming Language_ book?

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**Author:** ![Karl](https://avatars.discourse-cdn.com/v4/letter/k/34f0e0/32.png) [@Karl](https://forums.swift.org/u/Karl)\
**Post date:** [July 3, 2020, 7:14pm UTC](https://forums.swift.org/t/whats-transparent-for/38154/2 "2020-07-03T19:14:36Z")

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`@_transparent` is an underscored (stdlib-private) attribute. You shouldn’t use it in your own libraries or applications (given the sub-forum, you probably know this - just making it clear for anyone else).

But FWIW, it is documented: [swift/TransparentAttr.md at main · apple/swift · GitHub](https://github.com/apple/swift/blob/master/docs/TransparentAttr.md)

Other attributes are documented in the standard library programmer’s manual (but not all of them - for instance, it doesn’t appear that `@_alwaysEmitInToClient` is documented there): [swift/StandardLibraryProgrammersManual.md at main · apple/swift · GitHub](https://github.com/apple/swift/blob/master/docs/StandardLibraryProgrammersManual.md#annotations)

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<div class="post-metadata">

**Author:** ![beccadax](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/beccadax/32/34217_2.png) [@beccadax](https://forums.swift.org/u/beccadax)\
**Post date:** [July 3, 2020, 7:51pm UTC](https://forums.swift.org/t/whats-transparent-for/38154/3 "2020-07-03T19:51:48Z")

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`@_transparent` is an extremely strong form of `@inlinable` that ensures the call’s stack frame isn’t even preserved in the debug info. For example, if you try to set a breakpoint in `Int.+(_:_:)`, you’ll probably never see it hit in your program; this is because the operator is marked `@_transparent`.

Like all underscored attributes, `@_transparent` is not intended for ordinary language users and its meaning could change if we happen to need something different from it.