missing HexString documentation

[Mike Franklin]

On Wednesday, 7 February 2018 at 16:03:36 UTC, Steven 
Schveighoffer wrote:
>> 
>> They are deprecated:
>> 
>> https://dlang.org/changelog/pending.html#hexstrings
>> https://dlang.org/deprecate.html#Hexstring%20literals
>
> Wow, that's... a little superfluous.

I agree with the notion that the language should be an aggregate 
of primitives, and anything that can be composed of those 
primitives should be implemented in a library (unless a 
compelling reason is found to justify otherwise).  The 
deprecation of hex string literals has exposed flaws in the 
library implementation and the compiler's template 
implementation.  That doesn't mean deprecation was the wrong 
thing to do; it just brings the aforementioned flaws to the 
forefront, so let's not shoot the messenger.

Here's a few fundamental flaws I see in our library 
implementations.
* Some library implementations are not very cohesive, and have 
too many interdependencies.  This is what seems to prevent 
`HexString` from being used in -betterC.
* Some Phobos implementations would be quite useful in Druntime 
and in code that doesn't want to employ the runtime (e.g. 
libraries consumed by other languages, resource-constrained 
systems, and bare-metal programming), but alas, Druntime can't 
have a circular dependency on Phobos (nor should it).

This is a difficult problem, and I don't have any solutions; just 
ideas.  Maybe Phobos and Druntime should be divided into 3 
libraries:

1.  A library with no dependencies whatsoever, not even druntime, 
c runtime, or the C standard library.  Some stuff in 
`std.traits`, `std.conv`, and even `HexString` could go here.  
Let's call this library DLib.
2.  Druntime would only depend on DLib, but never publicly expose 
it.
3.  Phobos could depend on DLib or Druntime, but again, never 
publicly expose it.
4.  Phobos could be refactored by identifying packages that have 
too much coupling, and factoring out the dependencies into a 3rd, 
more cohesive library, imported by the previous two.

For extra credit:
2a. Move C/C++ standard library bindings to Deimos, and have the 
desktop OS ports import it privately.  There's no reason to 
impose this interface on bare-metal ports, and it's a superficial 
dependency anyway.
3a. Phobos shouldn't have any dependency on C/C++ language 
bindings.  DRuntime should expose an idiomatic D (and preferably 
@safe) interface for Phobos to use.

DLib could then be used in -betterC and other use cases where 
Druntime is more of a liability than an asset.

Mike