On a mutable associative it is valid to execute the following ( where x is associative )
x = Dict() y = x[:a] = 1.23 y has the value 1.23 on an immutable collection what does the following mean ? x = @NT( ) y = x[:a] = 1.23 Do I get a new version of x with the key :a and the value 1.23 ? On Wednesday, May 13, 2015 at 5:31:27 PM UTC-4, David Gold wrote: > > It also brings up an asymmetry between the overloaded [] operator for > immutable collections, where y = x[:a] is valid but x' = x[:b] = 1.23 is > not. I'm ok with this, but it does lead to some confusion. > > Would you please elaborate on this? I'm not sure I understand (I'm > confident the issue is on my end). > > On Wednesday, May 13, 2015 at 3:03:11 PM UTC-4, Michael Francis wrote: >> >> A little bit of both, I have defined what I would consider common verbs, >> they happen to not exist in Base today. So either they get added to >> Base, which in this instance may be the right thing or at some point in >> the future they will conflict and breakage will ensue. >> >> It also brings up an asymmetry between the overloaded [] operator for >> immutable collections, where y = x[:a] is valid but x' = x[:b] = 1.23 is >> not. I'm ok with this, but it does lead to some confusion. >> >> Most languages sidestep this by not having the ! annotation for mutation >> and rely on the type/number of arguments to define the behavior. I'm not >> necessarily advocating for this, but I would like some input from others on >> this. >> >> >> On Wednesday, May 13, 2015 at 2:51:47 PM UTC-4, Josh Langsfeld wrote: >>> >>> Is your concern that some other package might also export non-mutating >>> setindex and delete, thereby conflicting with yours? Or just that they >>> should exist in Base? >>> >>> On Wednesday, May 13, 2015 at 2:35:44 PM UTC-4, Michael Francis wrote: >>>> >>>> I added methods to NamedTuples.jl to support merge, set and delete. >>>> Since NamedTuples are essentially immutable dictionaries it seems >>>> incorrect >>>> to use the ! forms of setindex and delete. I now have an issue that these >>>> are not defined in base. How best to solve this? This is indirectly >>>> related >>>> to the thread on function name collapse, but any suggestions ? >>>> >>>> nt = @NT( a=>1, b=>2, c=>3 ) >>>> x = NamedTuples.setindex( nt, :x, 123 ) >>>> NamedTuples.delete( x, :a) # (b=>2,c=>3,x=>123) >>>> merge( nt, @NT( d => "hello", e => "world")) # ( >>>> a=>1,b=>2,c=>3,d=>"hello",e=>"world") >>>> >>>> >>>> >>>>
