Fix #53 with ismutable default

Default behavior is to use the `mutable` field of a type

Author: Tokazama

src/ArrayInterface.jl

@@ -72,9 +72,10 @@ https://github.com/JuliaDiffEq/RecursiveArrayTools.jl/issues/19.
 ismutable(x) = ismutable(typeof(x))
 
 ismutable(::Type{<:AbstractArray}) = true
-ismutable(::Type{<:Number}) = false
 ismutable(::Type{<:AbstractRange}) = false
-ismutable(::Type{<:Tuple}) = false
+ismutable(::Type{<:AbstractDict}) = true
+ismutable(::Type{<:Base.ImmutableDict}) = false
+ismutable(::Type{T}) where {T} = T.mutable
 
 # Piracy
 function Base.setindex(x::AbstractArray,v,i...)

test/runtests.jl

@@ -8,6 +8,8 @@ using StaticArrays
 @test ArrayInterface.ismutable(@MVector [1,2,3]) == true
 @test ArrayInterface.ismutable(1:10) == false
 @test ArrayInterface.ismutable((0.1,1.0)) == false
+@test ArrayInterface.ismutable(Base.ImmutableDict{Symbol,Int64}) == false
+@test ArrayInterface.ismutable((;x=1)) == false
 @test isone(ArrayInterface.known_first(typeof(StaticArrays.SOneTo(7))))
 @test ArrayInterface.known_last(typeof(StaticArrays.SOneTo(7))) == 7
 @test ArrayInterface.known_length(typeof(StaticArrays.SOneTo(7))) == 7
@@ -47,6 +49,7 @@ rowind,colind=findstructralnz(Sp)
 @test ArrayInterface.ismutable(spzeros(1, 1))
 @test ArrayInterface.ismutable(spzeros(1))
 
+
 @test !fast_scalar_indexing(qr(rand(10, 10)).Q)
 @test !fast_scalar_indexing(qr(rand(10, 10), Val(true)).Q)
 @test !fast_scalar_indexing(lq(rand(10, 10)).Q)