I think you're getting caught up on a red herring. Is your root problem
that the function isn't performing as well as you'd like? This is a well
known issue with anonymous functions. You'd be better off writing a for
loop to iterate over `j` yourself, or figuring out a way to make use of
Base's reduction functions.
On Tuesday, April 14, 2015 at 2:25:17 PM UTC-4, Isaiah wrote:
>
> I've highlighted in red below the part of the lambda that is of :(::) type.
>
>
>
> #s2 = cartesianarray(AST(:($(Expr(:lambda, {:(j::Any)},
>> {{},{{:j,Any,0}},{{:weights,Array{Float64,2},1}}}
>
>
>
> Sorry if I am being dense here, but:
>
> julia> typeof(:(j::Any))
>> Expr
>
>
> so, I still can't tell where you are seeing `:(::)` as a type. The code
> that you highlighted in red is just quoted. I'm guessing that what you are
> seeing is an artifact of the nested expression quoting (or quite possibly a
> bug in `show` for nested quote blocks).
>
> On Tue, Apr 14, 2015 at 11:36 AM, Todd Anderson <[email protected]
> <javascript:>> wrote:
>
>> I've highlighted in red below the part of the lambda that is of :(::)
>> type. When I first saw that, I assumed it was of SymbolNode type so I
>> added some code to handle that case but that code didn't execute. I then
>> inspected the type by hand and found it was of :(::) type. (It seems that
>> printing a SymbolNode won't print the type if the type is Any whereas :(::)
>> always prints the type. Also, note that for non-Any types, the print style
>> of SymbolNode and :(::) seem identical so you can't disambiguate them
>> easily through printing.)
>>
>> I can understand a difficulty in type inference for the array elements
>> that are being created. It seems like it should be an easier task though
>> to infer that at worst "j" is Unsigned.
>>
>> On Monday, April 13, 2015 at 7:19:22 PM UTC-7, Isaiah wrote:
>>>
>>> This shows the first lambda arg again as :(j::Any) of type :(::). In my
>>>> real code, it was at least figuring out in the second lambda arg to type
>>>> "j" as {:j,Int64,0} but in this example it doesn't even figure out that
>>>> "j"
>>>> has to be of some Unsigned type and punts back to Any ({:j, Any, 0}).
>>>
>>>
>>> I'm not sure I follow -- I don't see any type annotation of `:(::)`.
>>> However, more generally, there are currently some (known) limitations of
>>> Julia's type inference for anonymous functions. A do-block creates an
>>> anonymous function, so I would guess that is the underlying issue with the
>>> inferred types here.
>>>
>>> (By the way, have you seen the Cartesian macros in base?
>>> http://julia.readthedocs.org/en/release-0.3/devdocs/cartesian/)
>>>
>>> On Mon, Apr 13, 2015 at 7:46 PM, Todd Anderson <[email protected]>
>>> wrote:
>>>
>>>> Here's a small example:
>>>>
>>>> function nef(weights, input_B)
>>>> delta_B = cartesianarray(Float64, (input_B),) do j
>>>> sum(weights[spikes_A, j])
>>>> end
>>>> end
>>>>
>>>> ct = code_typed(nef, (Array{Float64,2}, Int64))
>>>>
>>>> println(ct)
>>>>
>>>> Here's the output:
>>>>
>>>> {:($(Expr(:lambda, {:weights,:input_B}, {{:#s2,:delta_B},{{:weights,
>>>> Array{Float64,2},1},{:input_B,Int64,0},{:#s2,Any,18},{:delta_B,Any,18}},{}},
>>>>
>>>> :(begin
>>>> #s2 = cartesianarray(AST(:($(Expr(:lambda, {:(j::Any)},
>>>> {{},{{:j,Any,0}},{{:weights,Array{Float64,2},1}}}, :(begin #
>>>> /mnt/home/taanders/pse-hpc/benchmarks2/nengo/ex2.jl, line 3:
>>>> return sum(getindex(weights,spikes_A,j))
>>>> end))))),Float64,input_B::Int64)
>>>> delta_B = #s2
>>>> return #s2
>>>> end))))}
>>>>
>>>> This shows the first lambda arg again as :(j::Any) of type :(::). In
>>>> my real code, it was at least figuring out in the second lambda arg to
>>>> type
>>>> "j" as {:j,Int64,0} but in this example it doesn't even figure out that
>>>> "j"
>>>> has to be of some Unsigned type and punts back to Any ({:j, Any, 0}).
>>>>
>>>
>>>
>
