Similarly,
julia> immutable bar
a::Float64
end
julia> bar(NaN) == bar(NaN)
true
julia> NaN == NaN
false
On Mon, Dec 7, 2015 at 8:24 PM, Seth <[email protected]> wrote:
> I was just about to post this result, which I don't understand. Why should
>
> 0.0 == -0.0
>
> but bar(0.0) != bar(-0.0) when bar is immutable? (yes, you can override ==
> for this to be ==(x::bar, y::bar) = x.a == y.a, but that seems as if it
> should be unnecessary.)
>
>
> On Monday, December 7, 2015 at 5:14:28 PM UTC-8, Yichao Yu wrote:
>
>> On Mon, Dec 7, 2015 at 7:01 PM, Davide Lasagna <[email protected]>
>> wrote:
>> > Cool! Thanks
>>
>> Also note that since your type is mutable, the default `==` is object
>> identity and your `a` and `b` won't equal even if their content are
>> the same by default. An `immutable` type will compare the content by
>> default (although `-0.0` and `0.0` have different bit pattern and
>> won't equal as a field by default as you pointed out).
>>
>> ```
>> julia> type foo
>> a::Float64
>> end
>>
>> julia> b = foo(0)
>> foo(0.0)
>>
>> julia> a = foo(0)
>> foo(0.0)
>>
>> julia> a == b
>> false
>>
>> julia> immutable bar
>> a::Float64
>> end
>>
>> julia> b = bar(0)
>> bar(0.0)
>>
>> julia> a = bar(0)
>> bar(0.0)
>>
>> julia> a == b
>> true
>>
>> julia> bar(0.0) == bar(-0.0)
>> false
>> ```
>>
>
