# UnionAll question

**URL:** <https://discourse.julialang.org/t/unionall-question/19741>\
**Category:** New to Julia\
**Created:** [January 17, 2019, 10:09am UTC](https://discourse.julialang.org/t/unionall-question/19741 "2019-01-17T10:09:30Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![hzgzh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hzgzh/32/6596_2.png) [@hzgzh](https://discourse.julialang.org/u/hzgzh)\
**Post date:** [January 17, 2019, 10:09am UTC](https://discourse.julialang.org/t/unionall-question/19741/1 "2019-01-17T10:09:30Z")

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why struct G{T\<:Real} ;end is right,and  
struct G{T} where T\<:Real ;end have error  
ERROR: syntax: invalid type signature

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [January 17, 2019, 10:13am UTC](https://discourse.julialang.org/t/unionall-question/19741/2 "2019-01-17T10:13:23Z")

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The second is invalid syntax (you may be confusing it with method type signatures). See the documentation:  
[https://docs.julialang.org/en/v1/manual/types/#Parametric-Types-1](https://docs.julialang.org/en/v1/manual/types/#Parametric-Types-1)

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**Author:** ![hzgzh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hzgzh/32/6596_2.png) [@hzgzh](https://discourse.julialang.org/u/hzgzh)\
**Post date:** [January 17, 2019, 10:20am UTC](https://discourse.julialang.org/t/unionall-question/19741/3 "2019-01-17T10:20:18Z")

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![image](https://global.discourse-cdn.com/julialang/original/3X/d/8/d8e33511647156ceab8ebea05e871b8a53c12387.png)  
but in UnionAll section,

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**Author:** ![hzgzh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hzgzh/32/6596_2.png) [@hzgzh](https://discourse.julialang.org/u/hzgzh)\
**Post date:** [January 17, 2019, 10:21am UTC](https://discourse.julialang.org/t/unionall-question/19741/4 "2019-01-17T10:21:04Z")

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where keyword is only used in function signatures?