'Path' implementation

[Brian T. Rice]

Brian T. Rice wrote:

> Hi Pavel,

>> ***********************************************************************
>> I tried to use ({#a -> #b} as: Dictionary) idiom, but it did not work 
>> - silently creating bogus dictionaries.  I believe I can fix this (by 
>> implementing special case of Dictionary WriteStream, I think), but I'm 
>> not sure if this should work at all (conceptually).
> 
> I think it's relevant idea, but there's obviously a missing method and 
> whatever method is getting applied needs to be overridden at the very 
> least. Silent failures (without even a comment on the method) like that 
> should just not happen. I'll take a look.

On further consideration, the problem is that sequences are mappings, so 
the keys are the indices and just get copied over like that, with the 
association as a value. A way around this is to do:

addSlot: #x valued: Dictionary newEmpty.
x add: #a -> #b.

which is hardly convenient. addAll: has the same problem as as: there, 
looking for keys and values automatically and using the sequence indices 
for it.

HOWEVER, I note that Streams are effectively index-less sequences, so I 
tried:

addSlot: #x valued: Dictionary newEmpty.
{#a -> #b. #c -> #d} reader >> x writer.

Which does what we obviously want. A single idiom for "a reader >> b 
writer" should probably be made, but it might conflate too much if it 
reused the >> selector. I'll think more on it.

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