Check if a value is present in an AbstractFill without iterating over it

[jishnub]

There's often no need to iterate over these special arrays to check if a value is contained in them.

Now

julia> A = Ones(10_000, 10_000);

julia> @btime 4000 in $(Ref(A))[]
  2.670 ns (0 allocations: 0 bytes)
false

julia> @btime 1 in $(Ref(A))[]
  2.670 ns (0 allocations: 0 bytes)
true

[codecov]

Codecov Report

Merging #136 (b7c7cd2) into master (59023c4) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
+ Coverage   95.53%   95.55%   +0.01%     
==========================================
  Files           4        4              
  Lines         515      517       +2     
==========================================
+ Hits          492      494       +2     
  Misses         23       23              

Impacted Files	Coverage Δ
src/FillArrays.jl	94.17% <100.00%> (+0.04%)	⬆️

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[dlfivefifty]

If you bump the patch version I can tag right away