# Please help me with the meaning of dot and three dots (...) in this code line:

**URL:** <https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170>\
**Category:** General Usage\
**Tags:** question\
**Created:** [January 18, 2023, 4:58pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170 "2023-01-18T16:58:51Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Kianoush\_Ramezani\_sh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kianoush_ramezani_sh/32/45765_2.png) [@Kianoush\_Ramezani\_sh](https://discourse.julialang.org/u/Kianoush_Ramezani_sh)\
**Post date:** [January 18, 2023, 4:58pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/1 "2023-01-18T16:58:51Z")

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(x → typeof(x)).(values(complexity\_of\_operators))…,  
Notes: complexity\_of\_operators is a dictionary  
I don’t know what the dot between the two parentheses means or what the … means at the end.

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**Author:** ![Jeff\_Emanuel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff_emanuel/32/15440_2.png) [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)\
**Post date:** [January 18, 2023, 5:33pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/2 "2023-01-18T17:33:54Z")

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. [Multi-dimensional Arrays · The Julia Language](https://docs.julialang.org/en/v1/manual/arrays/#Broadcasting)  
… [Frequently Asked Questions · The Julia Language](https://docs.julialang.org/en/v1/manual/faq/#The-two-uses-of-the-)…-operator:-slurping-and-splatting

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**Author:** ![LeePhillips](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/leephillips/32/205514_2.png) [@LeePhillips](https://discourse.julialang.org/u/LeePhillips)\
**Post date:** [January 18, 2023, 8:44pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/3 "2023-01-18T20:44:20Z")

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And to answer the first part of your question:

The `(x -> typeof(x))` part is an anonymous function that maps `x` to the type of `x` (the arrow should be two ascii characters, not the Unicode arrow in your example, at least on my system). The dot broadcasts the function to operate over the values of an array, returning an array as a result. So you can do in the REPL:

```julia
julia> (x -> typeof(x)).([1, 'x', "x"])                                                                                       
3-element Vector{DataType}:                                                                                                    
 Int64                                                                                                                        
 Char                                                                                                                         
 String         

```

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**Author:** ![DNF](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dnf/32/10191_2.png) [@DNF](https://discourse.julialang.org/u/DNF)\
**Post date:** [January 18, 2023, 8:47pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/4 "2023-01-18T20:47:40Z")

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> [@LeePhillips](#):
>
> (x → typeof(x))

Note also that there’s no reason to create an anonymous function here. This is the same as just `typeof`.

So

> [@LeePhillips](#):
>
> `(x -> typeof(x)).([1, 'x', "x"])`

is just

```julia
typeof.([1, 'x', "x"])

```

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**Author:** ![Kianoush\_Ramezani\_sh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kianoush_ramezani_sh/32/45765_2.png) [@Kianoush\_Ramezani\_sh](https://discourse.julialang.org/u/Kianoush_Ramezani_sh)\
**Post date:** [January 18, 2023, 9:07pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/5 "2023-01-18T21:07:07Z")

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Appreciated

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**Author:** ![Kianoush\_Ramezani\_sh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kianoush_ramezani_sh/32/45765_2.png) [@Kianoush\_Ramezani\_sh](https://discourse.julialang.org/u/Kianoush_Ramezani_sh)\
**Post date:** [January 18, 2023, 9:07pm UTC](https://discourse.julialang.org/t/please-help-me-with-the-meaning-of-dot-and-three-dots-in-this-code-line/93170/6 "2023-01-18T21:07:38Z")

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Appreciated