The reason is a little subtle, but it's because you have an abstract type
inside a parametric type, which confuses Julia. When you annotate
a::MyAbstractType, julia understands what to do with it (i.e. compiles
functions for each concrete subtype). When you annotate
a::Vector{MyAbstractType}, it is expecting a concrete type
Vector{MyAbstractType}, but you are in fact passing it a different concrete
type Vector{MyConcreteType}. Use the signature that Tim suggested to get
around the issue.
On Tuesday, April 28, 2015 at 10:08:57 AM UTC-4, Ján Dolinský wrote:
>
> Hi Tim,
>
> Thanks for the tip. Very interesting. In function definition it works. I
> read the parametric-composite-types manual. I am still puzzled however.
>
> Consider the example below which works as I expect:
>
> a = rand(10)
> b = rand(10,2)
>
> julia> a :: VecOrMat{Float64}
> 10-element Array{Float64,1}:
> ...
>
> julia> b :: VecOrMat{Float64}
> 10x2 Array{Float64,2}:
> ...
>
>
> The following example does not work as I would expect:
>
> a = Vector{Float64}[rand(10), rand(10)]
> b = Matrix{Float64}[rand(10,2), rand(10,2)]
>
> julia> a :: Vector{VecOrMat{Float64}}
> ERROR: type: typeassert: expected
> Array{Union(Array{Float64,1},Array{Float64,2}),1}, got
> Array{Array{Float64,1},1}
>
> julia> b :: Vector{VecOrMat{Float64}}
> ERROR: type: typeassert: expected
> Array{Union(Array{Float64,1},Array{Float64,2}),1}, got
> Array{Array{Float64,2},1}
>
> however, this:
> julia> a :: Vector{Vector{Float64}}
> 2-element Array{Array{Float64,1},1}:
> ...
> and this works:
> julia> b :: Vector{Matrix{Float64}}
> 2-element Array{Array{Float64,2},1}:
> ...
>
> Thanks,
> Jan
>
>
>
> Dňa utorok, 28. apríla 2015 13:13:36 UTC+2 Tim Holy napísal(-a):
>>
>>
>> http://docs.julialang.org/en/release-0.3/manual/types/#parametric-composite-types
>>
>>
>> Use foo{V<:VecOrMat}(X::Vector{V})
>>
>> --Tim
>>
>> On Tuesday, April 28, 2015 02:40:41 AM Ján Dolinský wrote:
>> > Hi guys,
>> >
>> > I am trying to write a function which accepts as an input either a
>> vector
>> > of vectors or a vector of matrices e.g.
>> >
>> > function foo(X::Vector{VecOrMat{Float64}})
>> >
>> > When running the function with a vector of matrices I get the following
>> > error " 'foo' has no method matching foo(::Array{Array{Float64,2},1})"
>> >
>> > Am I missing something here ?
>> >
>> > Thanks,
>> > Jan
>>
>>
