Rant time? Rant time.

FeepingCreature feepingcreature at gmail.com
Mon Sep 21 10:55:22 UTC 2020

On Monday, 21 September 2020 at 09:29:21 UTC, Tomcruisesmart 
> Hi,
> I'm looking for healthy conversation.
> What are the prominent downsides of the D programming language?

Okay, real talk.

D is *incredibly* uneven.

When it works well, it works great. When it breaks, it can break 
in really horrible ways that I can't accurately describe except 
by referencing Mickens' seminal article on systems programming 
[1] - that is what it is like, except replace pointers with 

Parts of the language are outright broken, everyone knows they're 
broken, this is not documented *anywhere*.

Parts of the standard library are not meant to be used. There's 
replacements that got proposed years ago and are languishing. Key 
projects that replace Phobos are written by individuals who may 
or may not reachable for issues. And there *will* be issues - 
templates can't be unittested completely at the site of 
definition, because you don't know all the cases you will 
encounter, so you can't even predict the types of your own 
variables sensibly.

immutable is broken with a good fraction of language and runtime 
features. shared is broken with another fraction. Synchronized 
has a hole the size of a truck that is unfixable without pulling 
in all of shared for no benefit. Incredibly useful DIPs like 
formatting string literals or named parameters are decided not by 
any kind of vote system, but by "let's see if anyone says in the 
thread that they don't like it, and then we won't do it." This 
leads to horrible DIPs that try to placate those people, which 
then leads to other people complaining that the DIP doesn't go 
far enough. There is no winning there, which is why language 
improvements are either trivial or depend on Walter deciding to 
just go for it.

Dub is the official build manager. Dub is included with the D 
distro. Dub has an open bug where it simply ignores the selected 
version when you try to run a binary with dub. Look at the 
unit-threaded prebuild line. [2] Just ... look at it. Dub has 424 
open bugs. Let's not talk about how many open bugs DMD has.

You can learn the core of D in an afternoon. You can get a good 
understanding of D in a month. Coming from C, D really is an 
incredible logically-designed language, and it's a joy to use. 
That's not the bad part of learning D.

The bad part is the years of picking up the problematic parts, 
the features to avoid, and the parts that are just silently 
broken. The bad part is the hours spent exploring "maybe I can do 
X", getting incredibly close, then failing due to a bug reported 
in 2012.

There's a reason so many D devs run off to develop their own 
language. D shows you what is possible with C-like languages, 
then falls short. It ruins you for other languages, but it's too 
frustrating to really love.

Still the best language I know. At least for now, until my 
current compiler project is off the ground...

[1] https://www.usenix.org/system/files/1311_05-08_mickens.pdf

[2] https://github.com/atilaneves/unit-threaded search for 

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