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STL has been both historically and recently slow in many ways. Many game devs are making their own engine, especially historically, so they just implement their

STL has been both historically and recently slow in many ways. Many game devs are making their own engine, especially historically, so they just implement their own version of STL in the way they want. Or they use another engine which has made its own replacement. Even Andreas of SerenityOS made his own entire STL (and also his own Objective-C like class system). The C++ STL is probably one of the most commonly avoided standard libraries of any language. I can’t think of another that is so often replaced by bespoke code

brabel 2y ago
When I was learning C++ in 2008, I remember people telling me STL was one of the greatest accomplishments in computer science.
- flohofwoe 2y ago
  It always depended on the specific C++ bubble you're in. The stdlib was also controversial back then (even in the late 90's when I started to use C++).
- bowsamic 2y ago
  Well, 2008 was a long time ago, but back then it was even worse.
- tialaramex 2y ago
  STL stands for Standard Template Library, which is an important piece of Generic Programming - it provides algorithms which are generic over the container types, so there's one library implementation of say sorting, and you can (but shouldn't) sort a linked list if you want to. When you see people asking why language X doesn't have "generics" this is the feature they're asking about - it's so fundamental now but in the 1990s it wasn't even obvious that you might want to write software this way. Generic Programming had been tried before, but the STL is an important idea and WG21 (the C++ Standards Committee) were persuaded to include it in the requirements for the new ISO standard. However, in C++ because the STL is a big part of their Standard Library, and because Microsoft insists on naming their entire implementation of the Standard Library STL, it's usual to say STL to mean the entire stdlib, even though many parts of it aren't about generic programming at all. So the STL is a crucial idea and inventing that was a tremendous accomplishment - but the C++ stdlib, which may be called "STL" and is in this article, is not a very good realisation of that idea. Indeed I'd argue the C++ programming language isn't a good realisation of that idea either - it was possible to write the STL for C++ and so that's what was done, but knowing this is a good idea you'd design the language differently. And people have.
  - lioeters 2y ago
    Thank you for an educational comment, the historical context was interesting to learn about. The last paragraph hints that there are more modern languages than C++ which implement generic programming in a better way, truer to its original conception?
    - samatman 2y ago
      I'm convinced, at this point, that Zig is that language, with comptime. Caveats: the system is not mature, Zig isn't 1.0 yet, there are some arbitrary limitations, the comptime type system is somewhat all-or-nothing, TL;DR it isn't done. All of this is immaturity, rather than an essential limitation of the design. The breakthrough with C++ templates, was to provide a macro system which creates an AST for a static language, at compile time, using (surprise!) a template of the desired code. Contrast with the C preprocessor, which works on the token stream (there's more to it if you're curious, but in a way that makes it worse, not better). Of course, a macro system operating on the AST is an older idea than C, this is one of the essential features of Lisp. But Lisps have always been dynamic languages. In some other timeline, there was an s-expression language for writing static programs, which used Lisp-style macros, and thereby avoided the problems with C++ templates. But we don't live in that timeline, it's a road not taken. This template system enabled C++ programmers to write code which was generic over not just types, but features of types, and much else, it's all rather complex. The problem, in essence, is that it was thought that template-expansion could be a decidable process implemented using a sub-Turing-complete language. So it was built using a second syntax, which was intended to be restrictive but flexible. Uh-oh! C++ templates are Turing complete, as it turns out. So what C++ has is a second language. You could write your entire program in that language, and execute it at compile time. For everything you can do in C++, there's a second way to do it in templates, with its own syntax and semantics. Invariably, this language is much more verbose, and just... weird, in big and small ways. The sum of this is a system which is difficult to understand, and which generates notoriously terrible errors. This isn't intended as a complete summary of C++ template's shortcomings and weird features. That would take longer. Zig just lets you run Zig at compile time. It's much, much better. Instead of trying and failing to make the problem decidable, Zig brute-forces the question by providing a branch quota: this is similar to gas in the EVM, or what Piccolo, a Rust implementation of Lua, calls "fuel". Comptime comes with a complexity limit, after which it quits, and which can be boosted for operations where the quota is insufficient. So there aren't two languages to learn, just the one: Zig. That glosses over some things, like loop and switch constructs have inline equivalents for comptime, but the general premise holds. There are other things which C++ makes easy which are less easy in Zig, like runtime polymorphism. But comptime is just a massive improvement over templates.
- kragen 2y ago
  they're right, but it's also almost 30 years old, and incorporates some unpleasant political compromises, as well as some failed experiments. you can do better, but unless you understand why the stl is one of the greatest accomplishments in computer science, you won't

brabel 2y ago

When I was learning C++ in 2008, I remember people telling me STL was one of the greatest accomplishments in computer science.

flohofwoe 2y ago
It always depended on the specific C++ bubble you're in. The stdlib was also controversial back then (even in the late 90's when I started to use C++).
bowsamic 2y ago
Well, 2008 was a long time ago, but back then it was even worse.
tialaramex 2y ago
STL stands for Standard Template Library, which is an important piece of Generic Programming - it provides algorithms which are generic over the container types, so there's one library implementation of say sorting, and you can (but shouldn't) sort a linked list if you want to. When you see people asking why language X doesn't have "generics" this is the feature they're asking about - it's so fundamental now but in the 1990s it wasn't even obvious that you might want to write software this way. Generic Programming had been tried before, but the STL is an important idea and WG21 (the C++ Standards Committee) were persuaded to include it in the requirements for the new ISO standard. However, in C++ because the STL is a big part of their Standard Library, and because Microsoft insists on naming their entire implementation of the Standard Library STL, it's usual to say STL to mean the entire stdlib, even though many parts of it aren't about generic programming at all. So the STL is a crucial idea and inventing that was a tremendous accomplishment - but the C++ stdlib, which may be called "STL" and is in this article, is not a very good realisation of that idea. Indeed I'd argue the C++ programming language isn't a good realisation of that idea either - it was possible to write the STL for C++ and so that's what was done, but knowing this is a good idea you'd design the language differently. And people have.
- lioeters 2y ago
  Thank you for an educational comment, the historical context was interesting to learn about. The last paragraph hints that there are more modern languages than C++ which implement generic programming in a better way, truer to its original conception?
  - samatman 2y ago
    I'm convinced, at this point, that Zig is that language, with comptime. Caveats: the system is not mature, Zig isn't 1.0 yet, there are some arbitrary limitations, the comptime type system is somewhat all-or-nothing, TL;DR it isn't done. All of this is immaturity, rather than an essential limitation of the design. The breakthrough with C++ templates, was to provide a macro system which creates an AST for a static language, at compile time, using (surprise!) a template of the desired code. Contrast with the C preprocessor, which works on the token stream (there's more to it if you're curious, but in a way that makes it worse, not better). Of course, a macro system operating on the AST is an older idea than C, this is one of the essential features of Lisp. But Lisps have always been dynamic languages. In some other timeline, there was an s-expression language for writing static programs, which used Lisp-style macros, and thereby avoided the problems with C++ templates. But we don't live in that timeline, it's a road not taken. This template system enabled C++ programmers to write code which was generic over not just types, but features of types, and much else, it's all rather complex. The problem, in essence, is that it was thought that template-expansion could be a decidable process implemented using a sub-Turing-complete language. So it was built using a second syntax, which was intended to be restrictive but flexible. Uh-oh! C++ templates are Turing complete, as it turns out. So what C++ has is a second language. You could write your entire program in that language, and execute it at compile time. For everything you can do in C++, there's a second way to do it in templates, with its own syntax and semantics. Invariably, this language is much more verbose, and just... weird, in big and small ways. The sum of this is a system which is difficult to understand, and which generates notoriously terrible errors. This isn't intended as a complete summary of C++ template's shortcomings and weird features. That would take longer. Zig just lets you run Zig at compile time. It's much, much better. Instead of trying and failing to make the problem decidable, Zig brute-forces the question by providing a branch quota: this is similar to gas in the EVM, or what Piccolo, a Rust implementation of Lua, calls "fuel". Comptime comes with a complexity limit, after which it quits, and which can be boosted for operations where the quota is insufficient. So there aren't two languages to learn, just the one: Zig. That glosses over some things, like loop and switch constructs have inline equivalents for comptime, but the general premise holds. There are other things which C++ makes easy which are less easy in Zig, like runtime polymorphism. But comptime is just a massive improvement over templates.
kragen 2y ago
they're right, but it's also almost 30 years old, and incorporates some unpleasant political compromises, as well as some failed experiments. you can do better, but unless you understand why the stl is one of the greatest accomplishments in computer science, you won't