Two-arg dot

[mcabbott]

There were some methods for dot(x,A,y), this adds similar ones for dot(x,y). Motivation:

julia> @btime dot($(rand(50,50)), Fill(1.0, 50, 50));
  2.329 μs (0 allocations: 0 bytes)

julia> @btime sum($(rand(50,50)));
  481.621 ns (0 allocations: 0 bytes)

I am a little concerned that methods with one ::AbstractArray argument are going to produce ambiguities, see what you think?

[dlfivefifty]

It’s apparently possible to test for ambiguities:

#105

[mcabbott]

Great, just saw that too. It found these, for which I've added methods like dot(a::Diagonal, b::AbstractFill{<:Any,2}):

 (dot(A::AbstractMatrix{T} where T, B::Diagonal) in LinearAlgebra at /Applications/Julia-1.6.app/Contents/Resources/julia/share/julia/stdlib/v1.6/LinearAlgebra/src/diagonal.jl:706, dot(a::FillArrays.AbstractFill, b::AbstractArray) in FillArrays at /Users/me/.julia/dev/FillArrays/src/fillalgebra.jl:145)
 (dot(D::Diagonal, B::AbstractMatrix{T} where T) in LinearAlgebra at /Applications/Julia-1.6.app/Contents/Resources/julia/share/julia/stdlib/v1.6/LinearAlgebra/src/diagonal.jl:701, dot(a::AbstractArray, b::FillArrays.AbstractFill) in FillArrays at /Users/me/.julia/dev/FillArrays/src/fillalgebra.jl:141)

[codecov]

Codecov Report

Merging #147 (e296f22) into master (a7ce2f8) will increase coverage by 0.11%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #147      +/-   ##
==========================================
+ Coverage   95.66%   95.78%   +0.11%     
==========================================
  Files           4        4              
  Lines         531      546      +15     
==========================================
+ Hits          508      523      +15     
  Misses         23       23              

Impacted Files	Coverage Δ
src/fillalgebra.jl	99.37% <100.00%> (+0.06%)	⬆️

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