(afaik requires @generated functions to take everything to a type stable
post-precompilation state)
assuming
(a1) If `typeof(x) == typeof(y)` then `typeof( t(x) )` is the same as
`typeof( t(y) )`.
(a2) If `typeof(x) != typeof(y)` then `typeof( t(x) )` might differ from
`typeof( t(y) )`.
(a3) There are relatively few (dozens not millions) possible types that x
may have when `t(x)` is called.
(b1) If `typeof(x) == typeof(y)` then `typeof( f2(x) )` is the same as
`typeof( t(y) )`.
(b2) If `T is the typeof(x) and T != typeof(y)`, `typeof( f2(t,
a::Vector{typeof(x)}) )` may differ from `typeof( f2(t,
a::Vector{typeof(y)}) )`.
(b2) There are relatively few (dozens not millions) possible types that T
may have when `f2{T}(t, a::Vector{T})` is called.
Given (a123), If you write one version of the function `t` for each
[abstract] type of x that is to be processed,
you could annotate each of them with the correct return type. If you can
do that, then you could create an
ObjectIdDict, t_oid, that maps the type of `x` to the return type of `t`.
Given (b123) and t_oid, you can create an
ObjectIdDict, f2_oid, that maps the type `T` in `f2` to the return type of
`f2`.
Using t_oid and f2_oid the return type for each call of `t` and each call
of `f2` is determinate and available.
On Monday, November 14, 2016 at 5:32:51 PM UTC-5, bogumil....@gmail.com
wrote:
>
> Actually I could do:
>
> function f2{T}(t, a::Vector{T})
> Dict{T, code_typed(t, (T,))[1].rettype}((x, t(x)) for x in a)
> end
>
> but this does not solve the problem as the compiler still is unable to
> determine the exact return type of f2.
>
> On Monday, November 14, 2016 at 4:06:20 PM UTC+1, Lutfullah Tomak wrote:
>>
>> You could find `ta=t.(a)` first and then construct a
>> `Dict{eltype(a),eltype(ta)}` but it is just a workaround and wastes some
>> memory.
>
>
