# Not() functional composition

**URL:** <https://discourse.julialang.org/t/not-functional-composition/695>\
**Category:** Internals & Design\
**Created:** [December 2, 2016, 2:03pm UTC](https://discourse.julialang.org/t/not-functional-composition/695 "2016-12-02T14:03:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![closescreen](https://avatars.discourse-cdn.com/v4/letter/c/ba9def/32.png) [@closescreen](https://discourse.julialang.org/u/closescreen)\
**Post date:** [December 2, 2016, 2:03pm UTC](https://discourse.julialang.org/t/not-functional-composition/695/1 "2016-12-02T14:03:41Z")

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Hi, all!  
How about add to Julia simple function not() ?

Sample:

not(f::Function) = (args…)-\>!f(args…)

julia\> filter(isempty , [“”,“asd”,“”,“too”] )  
2-element Array{String,1}:  
“”  
“”

julia\> filter( not(isempty) , [“”,“asd”,“”,“too”] )  
2-element Array{String,1}:  
“asd”  
“too”

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<div class="post-metadata">

**Author:** ![nalimilan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nalimilan/32/147_2.png) [@nalimilan](https://discourse.julialang.org/u/nalimilan)\
**Post date:** [December 2, 2016, 2:09pm UTC](https://discourse.julialang.org/t/not-functional-composition/695/2 "2016-12-02T14:09:14Z")

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See [this pull request](https://github.com/JuliaLang/julia/pull/17184).