Well, that's it then. Cause: accidental hash collision. The fix is to
define hash for the type. This makes me wonder if we shouldn't just leave
hash undefined for custom mutable types and make it easy to opt into
hashing by identity. At least then you'll get a clear no method error (and
we could trap that and add more helpful information), instead of weird
behavior when you define == but not hash for your types.
On Thu, Jul 16, 2015 at 11:39 AM, milktrader <milktra...@gmail.com> wrote:
> julia> hash(foos[1]) #and hash(foos[2])
> 0xfa40ebab47e8bee1
>
> julia> hash(foos[2])
> 0x00ef97f955461671
>
> On Thursday, July 16, 2015 at 11:36:03 AM UTC-4, Stefan Karpinski wrote:
>>
>> Dan and/or Seth, can you try that again and check if hash(foos[1]) and
>> hash(foos[2]) have the same last hex digit?
>>
>> On Thu, Jul 16, 2015 at 11:30 AM, Matt Bauman <mba...@gmail.com> wrote:
>>
>>> Bizarre. I happen to have last updated on *exactly* the same commit
>>> SHA, but I'm seeing the original (expected) behavior:
>>>
>>> $ julia -q
>>> julia> versioninfo()
>>> Julia Version 0.4.0-dev+5860
>>> Commit 7fa43ed (2015-07-08 20:57 UTC)
>>> Platform Info:
>>> System: Darwin (x86_64-apple-darwin14.3.0)
>>> CPU: Intel(R) Core(TM) i5 CPU M 520 @ 2.40GHz
>>> WORD_SIZE: 64
>>> BLAS: libopenblas (USE64BITINT NO_AFFINITY NEHALEM)
>>> LAPACK: libopenblas
>>> LIBM: libopenlibm
>>> LLVM: libLLVM-3.3
>>>
>>> julia> type Foo
>>> x::Int
>>> end
>>>
>>> julia> ==(f1::Foo, f2::Foo) = f1.x == f2.x
>>> == (generic function with 109 methods)
>>>
>>> julia> unique([Foo(4),Foo(4)])
>>> 2-element Array{Foo,1}:
>>> Foo(4)
>>> Foo(4)
>>>
>>> julia> @which hash(Foo(4), zero(UInt))
>>> hash(x::ANY, h::UInt64) at hashing.jl:10
>>>
>>> Might there be some package that changes this behavior? Is the result
>>> of `@which hash(Foo(4), zero(Uint))` the same as what I show above?
>>>
>>>
>>> On Thursday, July 16, 2015 at 11:02:46 AM UTC-4, Seth wrote:
>>>>
>>>> I can confirm this works as described by milktrader on 0.4.0-dev+5860
>>>> (2015-07-08 20:57 UTC) Commit 7fa43ed (7 days old master).
>>>>
>>>> julia> unique(foos)
>>>> 1-element Array{Foo,1}:
>>>> Foo(4)
>>>>
>>>>
>>>> On Thursday, July 16, 2015 at 7:52:03 AM UTC-7, Stefan Karpinski wrote:
>>>>>
>>>>> I don't see that on 0.4-dev – it also doesn't seem possible without
>>>>> having defined a hash method since unique is implemented with a dict.
>>>>>
>>>>> On Thu, Jul 16, 2015 at 10:29 AM, milktrader <milkt...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Julia 0.4- has different behavior ...
>>>>>>
>>>>>> First, with 0.3.9
>>>>>>
>>>>>> julia> versioninfo()
>>>>>> Julia Version 0.3.9
>>>>>> Commit 31efe69 (2015-05-30 11:24 UTC)
>>>>>> Platform Info:
>>>>>> System: Darwin (x86_64-apple-darwin13.4.0)
>>>>>> CPU: Intel(R) Core(TM)2 Duo CPU P7350 @ 2.00GHz
>>>>>> WORD_SIZE: 64
>>>>>> BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Penryn)
>>>>>> LAPACK: libopenblas
>>>>>> LIBM: libopenlibm
>>>>>> LLVM: libLLVM-3.3
>>>>>>
>>>>>> julia> type Foo
>>>>>> x::Int
>>>>>> end
>>>>>>
>>>>>> julia> import Base: ==
>>>>>>
>>>>>> julia> ==(f1::Foo, f2::Foo) = f1.x == f2.x
>>>>>> == (generic function with 80 methods)
>>>>>>
>>>>>> julia> foos = [Foo(4), Foo(4)]
>>>>>> 2-element Array{Foo,1}:
>>>>>> Foo(4)
>>>>>> Foo(4)
>>>>>>
>>>>>> julia> unique(foos)
>>>>>> 2-element Array{Foo,1}:
>>>>>> Foo(4)
>>>>>> Foo(4)
>>>>>>
>>>>>> julia> unique(foos)[1] == unique(foos)[2]
>>>>>> true
>>>>>>
>>>>>> And now 0.4-dev
>>>>>>
>>>>>> julia> versioninfo()
>>>>>> Julia Version 0.4.0-dev+5587
>>>>>> Commit 78760e2 (2015-06-25 14:27 UTC)
>>>>>> Platform Info:
>>>>>> System: Darwin (x86_64-apple-darwin13.4.0)
>>>>>> CPU: Intel(R) Core(TM)2 Duo CPU P7350 @ 2.00GHz
>>>>>> WORD_SIZE: 64
>>>>>> BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Penryn)
>>>>>> LAPACK: libopenblas
>>>>>> LIBM: libopenlibm
>>>>>> LLVM: libLLVM-3.3
>>>>>>
>>>>>> julia> type Foo
>>>>>> x::Int
>>>>>> end
>>>>>>
>>>>>> julia> import Base: ==
>>>>>>
>>>>>> julia> ==(f1::Foo, f2::Foo) = f1.x == f2.x
>>>>>> == (generic function with 108 methods)
>>>>>>
>>>>>> julia> foos = [Foo(4), Foo(4)]
>>>>>> 2-element Array{Foo,1}:
>>>>>> Foo(4)
>>>>>> Foo(4)
>>>>>>
>>>>>> julia> unique(foos)
>>>>>> 1-element Array{Foo,1}:
>>>>>> Foo(4)
>>>>>>
>>>>>> julia> unique(foos)[1] == unique(foos)[2]
>>>>>> ERROR: BoundsError: attempt to access 1-element Array{Foo,1}:
>>>>>> Foo(4)
>>>>>> at index [2]
>>>>>> in getindex at array.jl:292
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thursday, July 16, 2015 at 9:36:21 AM UTC-4, Stefan Karpinski
>>>>>> wrote:
>>>>>>>
>>>>>>> You need to also define a hash method for this type.
>>>>>>>
>>>>>>>
>>>>>>> On Jul 16, 2015, at 9:16 AM, Marc Gallant <marc.j....@gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>> The unique function doesn't appear to work using iterables of custom
>>>>>>> composite types, e.g.,
>>>>>>>
>>>>>>> julia> type Foo
>>>>>>> x::Int
>>>>>>> end
>>>>>>>
>>>>>>> julia> import Base: ==
>>>>>>>
>>>>>>> julia> ==(f1::Foo, f2::Foo) = f1.x == f2.x
>>>>>>> == (generic function with 85 methods)
>>>>>>>
>>>>>>> julia> unique(foos)
>>>>>>> 2-element Array{Foo,1}:
>>>>>>> Foo(4)
>>>>>>> Foo(4)
>>>>>>>
>>>>>>> julia> unique(foos)[1] == unique(foos)[2]
>>>>>>> true
>>>>>>>
>>>>>>>
>>>>>>> Is this the intended behaviour?
>>>>>>>
>>>>>>>
>>>>>
>>
