It seems dictionaries uses identity instead of equality, to determine the
uniqueness of the key:
ismaelvc@toybox ~> julia
_
_ _ _(_)_ | A fresh approach to technical computing
(_) | (_) (_) | Documentation: http://docs.julialang.org
_ _ _| |_ __ _ | Type "help()" to list help topics
| | | | | | |/ _` | |
| | |_| | | | (_| | | Version 0.3.0-prerelease+1419 (2014-02-06 22:55
UTC)
_/ |\__'_|_|_|\__'_| | Commit a673e4c* (1 days old master)
|__/ | i686-pc-linux-gnu
julia> Int # I'm on 32 bit version.
Int32
julia> d = Dict{Integer, Integer}()
Dict{Integer,Integer}()
julia> d[3] = 1
1
julia> d[convert(Int64, 3)] = 5
5
julia> for (key, val) in d
println("The key: $(key), of type: $(typeof(key)), maps to:
$(val)
Bits representation: $(bits(key))")
end
The key: 3, of type: Int32, maps to: 1
Bits representation: 00000000000000000000000000000011
The key: 3, of type: Int64, maps to: 5
Bits representation:
0000000000000000000000000000000000000000000000000000000000000011
julia> x, y = keys(d)
KeyIterator{Dict{Integer,Integer}}([3=>1,3=>5])
julia> x, typeof(x)
(3,Int32)
julia> y, typeof(y)
(3,Int64)
julia> x == y # Tests equality
true
julia> x === y # Tests identity
false
julia> is(x, y) # Same as: x == y
false
julia> help(===)
Loading help data...
Base.is(x, y)
Determine whether "x" and "y" are identical, in the sense that
no program could distinguish them. Compares mutable objects by
address in memory, and compares immutable objects (such as numbers)
by contents at the bit level. This function is sometimes called
"egal". The "===" operator is an alias for this function.
julia> d = Dict{Int64, Int32}()
Dict{Int64,Int32}()
julia> d[convert(Int64, 3)] = 5
5
julia> get(d, 3, 0) # Calling with the Int32 key:
0
julia> get(d, convert(Int64, 3), 0) # Needs to be the same Int64 type:
5
