On Friday, May 6, 2016 at 2:18:42 PM UTC-4, David Dill wrote:
>
> It's a bit surprising that, if d1 is mentioned for the first time in d1 =
> d2 = Dict() in f7 below, the inferred type of d1 is different from the
> inferred type of d2, especially since the inferred type is different in d8.
>
The type of d2 isn't inferred -- you explicitly declared it as
Dict{Int,Int} in the line above.
As for d1, the key thing to remember is that the value of an assignment
operation is equal to the *right-hand* side. That is, in a=b=c, c is
assigned to both a and b. More explicitly, in your example, d1 = d2 =
Dict() is equivalent to
let temp = Dict() # gives a Dict{Any,Any}
d2 = temp # requires a conversion (hence a copy) since d2 was
declared as Dict{Int,Int}
d1 = temp # since d1's type was not declared, it is inferred to
be that of temp, hence no copy is needed
end
