Persistent list

[Steven Schveighoffer via Digitalmars-d]

On 11/16/15 11:03 AM, Steven Schveighoffer wrote:
> On 11/14/15 10:44 AM, Andrei Alexandrescu wrote:
>
>> That doesn't work for me with my unittests, I get:
>
>
> I'm such an idiot, I depended on dpaste to run the unit test, but forgot
> to check the unit test button.
>
> So technically, my updated version *parses* correctly :)
>
> Looking in more depth...
>

I can't get your original code to work, so it's hard for me to figure 
out what is wrong. Using 2.069.1, I have the following error (after 
factoring out `either`, which I'm assuming is a new function):

Stevens-MacBook-Pro:testd steves$ dmd -unittest persistent_list.d
/Users/steves/.dvm/compilers/dmd-2.069.1/osx/bin/../../src/phobos/std/conv.d(4161): 
Error: template std.conv.emplaceImpl!(const(Node)).emplaceImpl cannot 
deduce function from argument types !()(const(Node), immutable(int), 
const(Node)*, int), candidates are:
/Users/steves/.dvm/compilers/dmd-2.069.1/osx/bin/../../src/phobos/std/conv.d(3932): 
        std.conv.emplaceImpl!(const(Node)).emplaceImpl()(ref UT chunk)
/Users/steves/.dvm/compilers/dmd-2.069.1/osx/bin/../../src/phobos/std/conv.d(4037): 
        std.conv.emplaceImpl!(const(Node)).emplaceImpl(Args...)(ref UT 
chunk, auto ref Args args)
/Users/steves/.dvm/compilers/dmd-2.069.1/osx/bin/../../src/phobos/std/conv.d(5087): 
Error: template instance std.conv.emplace!(const(Node), immutable(int), 
const(Node)*, int) error instantiating
persistent_list.d(169):        instantiated from here: 
emplace!(const(Node), immutable(int), const(Node)*, int)
persistent_list.d(195):        instantiated from here: opBinaryRight!"~"
persistent_list.d(266):        instantiated from here: List!(immutable(int))

However, examining the code, I think you don't even need inout here, 
just a const function will do fine, since nothing on the original is 
changing, and all your nodes are flavored as pointing to const nodes.

I see you have updated the code, and that doesn't work for me either.

I'm afraid without a working example, I can't figure out what's 
*supposed* to work with inout/const.

-Steve