Questions tagged [language-design]
Questions involving the design and structure of programming languages.
493 questions
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Why does C allow escaping apostrophes / single quotation marks in string literals
As far as I can tell, the strings "It's me" and "It\'s me" are always identical. There seems to be no reason when a programmer needs to escape '. Yet, I could not find and ...
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A [[byvalue]] attribute for C++?
Background
C++ attributes are a useful way to document assumptions and intent within code, and to prevent warnings. (e.g. [[fallthrough]])
Now, the Core Guidelines recommend to For “in” parameters, ...
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Is there precedent for a language that allows the "early return" pattern to go between function call boundaries?
Here's some C# that should illustrate what I'm asking.
Thing FindThing(string key)
{
// Search for the thing with the right key.
foreach (Thing th in things)
{
// Found it?
if (...
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Go, Error Handling, and Big Text Files - express error semantics in types
The title Go, Error Handling, and Big Text Files is a blog post from Wesley Aptekar-Cassels from 2021. In this blog post he reports about a problem he faced parsing long text files. He tried
scanner :=...
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Swift: What is the rationale behind forbidding named parameters for closures?
In Swift, functions can be defined with named parameters, for example:
func greet(person: String) -> String {
...
}
which need to be used when the function is called :
greet(person: "Anna&...
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Why did Python designers decide not to declare vars? [closed]
In Python when you want a local variable, you just assign to it x = 10.
In most modern languages you declare local vars (regardless of type):
JavaScript: let/const/var
Swift: let/var
Kotlin: val/var
...
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Why don't many languages implement an everything-before-is-a-comment symbol?
Python and PowerShell use # to denote to the parser that everything after them until the line break is a comment. They even provide block comments for multiline situations. However, there is no ...
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Is it possible to build a semantically unambigous grammar / language / graph?
It's been a long time that I had an idea of a semantic constraint as compiler optimizations which allows for sophisticated high level optimization allowing you to transform the AST/CFG based on a SFG (...
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Could there be a <flex> tag?
<div> tags are display: block per default. <span> tags are display: inline per default. Could there be a tag that is display: flex per default? I don't mean a class, like bootstrap has. I ...
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Bytecode format and loading in language VMs
I am thinking about how to build a language VM. I have been able to get some of the basic constructs right, including jumps to functions within the chunk of bytecode that is currently loaded.
But now ...
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Advantage of implicit/explicit declaration of global symbols (like functions)
In C and C++ we need to declare a function before its usage, if its definition comes after where it is called. (Well, there is also the "implicit declaration" rule in C, but it is rarely ...
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Does a programming language with ML-style modules need packages?
This is a clarification of a closed question. I've limited the scope as requested.
First, a few definitions, following e.g. A modular module system. Consider any programming language with a selected ...
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How to model opcodes effectively for a language VM?
I am learning about building a language VM with the long-term goal of writing an own language.
For guidance, I am looking at this LC3 tutorial by Justin Meiners and Building a Language VM by Fletcher ...
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Why don't languages auto import everything?
Why is there a such thing as import in programming languages? If a package does not exist, then trying to import it would cause an error anyway. So why don't languages just auto import ALL available ...
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Is it a good idea to let keywords have different lexical rules from names of types, variables, functions, etc? [closed]
For example, keywords have a special prefix. Objective-C has @interface, @implementation, but that's for compatibility with C. It inherits all the C keywords of course, with no @.
How about a language ...
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Why does Rust allow a leading `|` in or patterns?
In the code snippet found in this tweet, pattern matching is used like this:
let (|x| x) = |_| Some(1); // same as `let (x | x) = |_| Some(1);`
Which threw me off. Rust's pattern syntax is defined as:...
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Why do heavily object-oriented languages avoid having functions as a primitive type?
As has been covered to the point of parody, heavily object-oriented languages, such as C# or Java, tend to lack the feature of having functions as a primitive type. You can argue about whether or not ...
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Can we reliably use unaligned scalars on contemporary hardware?
Processors have come a long way in their handling of unaligned data - from crashing at the very notion of it, through suffering severe penalties, all the way to having almost no impact.
I suppose it ...
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What are the trade-offs between garbage collection and Automatic Reference Counting?
By "Automatic Reference Counting", I am refering to the specific feature of the Clang compiler. By "Garbage Collection", I am refering to Tracing Garbage Collection, not to "...
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Why does HTML collapse whitespace?
I've been trying to better understand (at least at a high level) why the early versions of HTML were designed the way they were. Most of the decisions make sense; I can deduce (at least at a high ...
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What is the purpose of a delegate type variable?
In C#, we have delegates, which are essentially variables (holders) for methods that follow a signature. So, I could write
delegate void MyDelegate(int num);
MyDelegate myMethodHolder;
Now, ...
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Is there any performance hit associated by the definition of a static constructor or due to availability of it?
This question is mostly related to the way language implementer do implements static class initalization (pretty specialized question). It is for curiosity and also to potentially improve my code to ...
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Is there a language implemented as a neuron network?
Does there exist some language whose execution model is implemented as a neuron network, or maybe as some other type of a network/grid (e.g. network of finite automata)? That is, specifically, without ...
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How can Python, a language that supports Object Oriented Programming, be implemented in C, which is not an Object Oriented Programming language?
To my understanding, C does not have the concept of objects, then how can Python be implemented in C to support something that C can not? How is the concept of "Object" modeled in C? What is ...
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Hot reloading anonymous functions in a custom scripting language
I am implementing anonymous functions (lambdas) in a scripting language that supports hot reloading. The language currently supports passing user defined functions (pointers) to plugin functions which ...
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Is there a cancel after certain amount of time try catch type of block?
I'm going through a beginner programming learning guides and the teacher brings up the try catch block paradigm.
The code you put in the try block is run and if an error happens the code in the catch ...
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What type of syntax notation is this?
SQL Server documentation uses this notation, which is very easy to understand and consume. Is this a BNF Syntax Diagram? Or is this a different type of notation?
Source: SQL server documentation page ...
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Do any programming languages use types as values? Would there be any point?
The standard way that types are handled in programming languages that have such a concept, is that they are:
removed entirely at compile time and are just used to determine memory layout, function ...
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Appropriate base type for simply typed lambda calculus
Given the following hypothetical programming language:
Intended for practical programming
A simply typed lambda calculus (STLC)
All objects are functions, based on Church encodings
I am aware that ...
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Why don't languages like C have NAND operators?
I know that some languages like APL have a dedicated NAND operator, but I'm thinking about languages like C, C++, Java, Rust, Go, Swift, Kotlin, even instruction sets, etc. since these are the ...
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Why are constants declared with `let`?
A few weeks ago, I went on Udemy course on Swift, the instructor mentioned that constants are called let in Swift because it's standard in OOP (JavaScript uses it for example).
I know this may seem ...
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Why do "checked exceptions", i.e., "value-or-error return values", work well in Rust and Go but not in Java?
Java has "checked exceptions", which force the caller of the method to either handle an exception or to rethrow it, e.g.
// requires ParseException to be handled or rethrown
int i = ...
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What advantage is gained by continuing to not provide an UPSERT statement in T-SQL (or any given major SQL dialect)?
This question is asking about a generally applicable engineering principle. It is using T-SQL as a specific example, but the question is about the engineering principles behind major SQL dialects in ...
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Choosing the design of a scientific DSL: purely or impurely functional?
My aim is to create a language specific to the scientific field (which would be used mainly in the field of machine learning and physics) which would be based on the functional paradigm, a paradigm ...
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Reasons to use (and not to use) a repeated delimiter to escape that delimiter?
For the designer of a language syntax, what are some reasons to choose a repeated delimiter to escape that delimiter, instead of having a separate escape character to escape that delimiter. A common ...
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How do covariant parameterized types nested inside invariant parameterized types act?
Here is a concrete example of what I'm asking about:
MutableList[ImmutableList[Object]]
Where ImmutableList is covariant wrt its first parameter, but MutableList is invariant wrt its first parameter. ...
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Why have separate keywords for 'extends' and 'implements' in Java? [closed]
Short answer that I've come to accept:
Firstly, it helps with readability, being able to see which is the superclass apart from interfaces. Secondly, though 'extends' and 'implements' do the same ...
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Real-world scenarios for protected inheritance
C++ supports protected inheritance: A class can derive from a base class B in a way that the "outside" world doesn't see that class "as a B" but the class itself and it's derived ...
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Is there a statically typed programming language that implements Polymorphism without using a superclass or an interface?
Is there a statically typed programming language that implements Polymorphism without using a superclass or an interface (if such implementation is even possible)?
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How to deal with metaclasses in strong-typed language : is it ok to mix classes and metaclasses?
I'm working on a programming language design ans I'm struggling with how I should type the concept of Class.
Let me show you some code to illustrate my problem :
class MyClass
{
}
function ...
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A language design with variable qualifier
I am planning to design a programming language. One challenge I face with is whether it is a good idea to have const as a variable qualifier instead of a type qualifier.
For example in C++:
const int ...
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Why does C++ have classes?
The title is deceptive; the question is really "why does C++ have classes and not only structs?"
Often, people ask why C++ has structs if they are functionally equivalent to classes. The answer is (...
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Can syntactic `await` always be elided?
(This question isn't a duplicate of Why do we need the async keyword? - it's more of the opposite: I'm not questioning the async keyword - I'm asking if compilers could elide the use of await ...
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Why F#, Rust and others use Option type instead of nullable types like C# 8 or TypeScript?
AFAIK, Option type will have runtime overhead, while nullable types won't, because Option time is an enum (consuming memory).
Why not just mark optional references as optional, then the compiler can ...
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In C++, Why do bitwise operators convert 8 or 16 bit integers to 32 bit?
Is there a logical reason why the integer is upgraded to 32+ bits?
I was trying to make an 8bit mask, and found myself a bit disappointed that the upgrade will corrupt my equations.
sizeof( quint8(0)...
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Design decisions behind access modifiers in C#
I'm currently writing a small language of my own, and have been considering the difference between the C++ style, where the access modifier applies to a block of members, and the C#/Java style, where ...
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Why did C++11 add find_if() instead of overloading find()?
Why did c++11 add a separate find_if() instead of simply overloading the existing find()?
Wouldn't overloading the function be sufficient?
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Language design : use equals symbol = both for affectation and comparison, like in MySQL
I'm currently designing a database query language and I came to wonder what should be the best syntax for the comparison operator.
Most modern languages use ==, but amongst the database languages ...
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What makes a scripting language "embeddable"?
According to my experience, Wikipedia and prior answers, a scripting language is vague category of languages which are high-level (no manual memory management) and interpreted. Popular examples are ...
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Is it a good idea to use a Parser Combinator to parse unstructured input?
I'm writing a parser that needs to accept unstructured input. By that I mean it needs to take in a raw signal (text, in this case) and look for significant character sequences while accumulating the ...
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