Questions tagged [programming-languages]

Questions related to design, implementation, and analysis of programming languages. NOT for questions about how to program, which are off-topic on this site.

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41 views

How does the undecidability of Extensional Martin-Löf Type Theory apply to real type-checking compilers?

It is claimed in many sources (for example, here) that adding a rule like "if Id(X,Y) then X really equals ...
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1answer
17 views

How would you model Rust procedural macros?

In Rust programming language one can write a compiler extension function that works on abstract syntax tree, effectively modifying source code before it gets converted into machine instructions. In ...
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key benefit of using container?

I'm not a guy who has computer science related background, just curious about the container technology and of course I did some googling to see what container is. hope this is the correct site for ...
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1answer
34 views

Java programming object terminology

Say there is a class called Person. Then in the following expression : Person human = new Person() Which is the "reference&...
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1answer
39 views

doubts on cin and scanf [closed]

i spent literally 5hrs trying to figure out, why the value of n is 1 for my second test case ( which begins at line 12 ) , but i am unable to, could you help me with that? ...
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1answer
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Can you use binary files to reverse engineer cpu architecture?

I wanted to know if it was possible to add code directly to a computer without an operating system or any programming language. To do that, I thought that maybe I could use the binary files to reverse ...
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1answer
68 views

Type-checking function calls with functional subtyping

I'm relatively new to the topic. Suppose that you want to type-check an expression of the form f(a), i.e. a function call. Assuming that all the declarations are ...
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0answers
20 views

How would I convert separate digits to an actual number?

In Dr. Racket, how would I combine the digits w, x, y, z to wxyz (for example 3, 7, 8, 9 to 3,789)? I haven't gotten very far on this: (define digits-to-numbers w x y z)
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1answer
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what are the weakest preconditions of these following statements

what is the meaning of postcondition and weakest postcondition in terms of programing and what are weakest postconditons of following statements. ...
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0answers
22 views

Regular expressions accepted by programming languages but are not regular [duplicate]

The below definition of Regular Language is given in Wikipedia. In theoretical computer science and formal language theory, a regular language (also called a rational language) is a formal language ...
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5answers
4k views

What is the formal, rigorous definition of a programming language?

In programming language theory, people study the theory behind programming languages. But I have never heard any formal definition of programming languages themselves. What is the formal definition, ...
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0answers
47 views

Semantics of “write-once” variables for complex data structures

Question My use case for what is described below is not a language or compiler implementation, but finding a reasonable semantics for this feature in a an abstract calculus. Ideally, you give me a ...
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2answers
56 views

Are C standard library functions considered part of C programming language

Do we consider functions like printf part of C language even if it's not a keyword in it.
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1answer
35 views

First-order mutual-recursive functions Turing-complete or incomplete?

Assume we have a C-like programming language with no pointer/heap semantics (i.e. there is no concept of memory; everything is on the stack). The only datatype supported is Integer, but suppose the ...
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1answer
42 views

Terms for different models of sum types

There seem to be at least a couple different possible ways of modeling sum types in a type system, but I haven't been able to find consistent terms for referring to them: A sum type is formed from a ...
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1answer
40 views

In the dataflow programming paradigm programs are modeled as directed graphs. Are the edges of the graph variables? And are the vertexes functions?

As I understand it in dataflow programming, programs are structured as directed graphs, an example of which is below Is it true to say that the arrows (or edges) represent the variables within a ...
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0answers
58 views

What's the meaning of linguistics?

In the programming language theory world, there are two important terminologies, i.e syntax, and semantics. I can understand these two terminologies: syntax is about sentence's structure (e.g. a valid ...
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2answers
40 views

What programming language should I use to run physics simulations of CO2 being absorbed by different materials?

I want to model the absorption of CO2 with multiple different materials such as cement, limestone, wood, etc? I know Matlab is capable of these types of physics simulation according to this research ...
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1answer
50 views

How to view Graph Reduction/Graph Representation for a Haskell program?

I know that under the hood, for a Haskell program, the GHC compiler uses graph reduction for optimization. Is there any way to view this graphical representation of the program? I haven't been able to ...
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0answers
58 views

What does it take to create a new programming language and its toolchain?

I am super novice to this topic, so my apologies if my question looks completely nonsense to you all! Imagine you want to create a new programing language that transpiles to a more common high/low-...
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Exceptions from exceptions, does such a thing exist?

I am intrigued: In many languages there are both normal control flow and exceptions. But I never saw "an exception from an exception" or "an exception from an exception from an ...
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5answers
7k views

Why do more powerful programming languages tend to have slower implementations?

I was reading this article. The author talks about "The Blub Paradox". He says programming languages vary in power. That makes sense to me. For example, Python is more powerful than C/C++. ...
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0answers
24 views

Question regarding definition of recursive function

According to Wikipedia, and also a very common definition of a recursive function found in several books, "functions that call themselves from within their own code". I agree that this solves the ...
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3answers
844 views

Where should I start to understand how computers work? [duplicate]

I am interested in how computers work but I have no idea how the concept of 0's and 1's converts to making possible for people to control a computer by programming. I would like to understand from ...
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2answers
101 views

Do there exist coding languages where the halting problem is solvable but not trivial

Does there exist a coding language where 1. It is always possible to determine whether a computer program will halt or run forever. And 2. The answer is not always yes. (or always no) So languages ...
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1answer
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How to prove that replacing a character in a string in both C and JavaScript is equivalent?

I would like to try some different proofs, specifically in proving equivalence of the implementation of some feature in two different programming languages (C and JS in this question). This is about ...
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1answer
61 views

Difference between assignment, binding, and substitution?

I am trying to understand the difference of assignment, binding, and substitution. I know the three things are related, but to me it's not exactly clear what word refers to what. Example, illustration,...
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1answer
42 views

How to write a custom editor for a new programming language? [closed]

Let's say I've finished my compiler for my new language. Next step is write a custom editor with syntax highlighting (type checking and semantic can wait), is there a cookbook or any kind of guidance ...
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3answers
89 views

Uncurrying and Polymorphism

How do we uncurry functions when they are polymorphic? For example, is it possible to uncurry the following types? If so what is the uncurried type? $\forall X. X \rightarrow int \rightarrow X$ ? $...
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0answers
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Lambda calculus and runtime inspection of the term

This is possibly related to reflection and quoting but I don't want to assume anything beforehand. Here is my requirement. My typed lambda calculus (Curry style) is a simpler variant of Calculus of ...
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4answers
4k views

Do you ever “download” a language?

When one "downloads" a language (say, downloading the python file, or doing apt-get ruby or something), is it always the ...
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0answers
16 views

Term for language that abstracts program location?

What is the technical term that describes a programming language that abstracts (or at least largely abstracts) the machine location of programs? I’m thinking here specifically of the evolution of ...
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6answers
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Halting problem theory vs. practice

It is often asserted that the halting problem is undecidable. And proving it is indeed trivial. But that only applies to an arbitrary program. Has there been any study regarding classes of programs ...
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0answers
36 views

What are symbols and symbol references in Scheme?

Practical Foundation of Programming Languages by Harper distinguishes concept "symbol" and concept "symbol reference" which refers to a symbol: Chapter 31 Symbols In this chapter, we consider ...
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0answers
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How is a symbol “given meaning by a family of operations indexed by symbols”?

Practical Foundation of Programming Languages by Harper says: Chapter 31 Symbols A symbol is an atomic datum with no internal structure. Whereas a variable is given meaning by substitution, ...
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What are the implementation strategies for multiple dispatch: class-based, or method-based organization, or either?

Regarding classes and methods, Practical Foundation of Programming Languages by Harper says: Dynamic dispatch is often described in terms of a particular implementation strategy, which we will ...
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2answers
58 views

What is the single type in a dynamic typing language?

Regarding static typing and dynamic typing, Practical Foundation of Programming Languages by Harper says: There have been many attempts by advocates of dynamic typing to distinguish dynamic from ...
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1answer
48 views

Do dynamic/static languages associate types or classes to values or variables?

In Practical Foundation of Programming Languages by Harper There have been many attempts by advocates of dynamic typing to distinguish dynamic from static languages. It is useful to consider ...
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1answer
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What is the time complexity of the following triple nested loop? Kindly solve in term of n

I want to ask that what is the time complexity of this function (triple nested loop) .Kindly analysis completely so that I can understand. ...
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1answer
33 views

More the number of for loops greater the problems solved

This is more a formal language theory question. Imagine a setting where you are given a very basic programming language where variable assignments etc are taken care of without any of the iteration ...
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1answer
27 views

Interactive programming language minimizing reevaluations

I'm looking for any programming language, DSL, library or pattern for live scripting but minimizing the expressions reevaluation. Topological sorting provides non-revaluation of expressions. ...
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2answers
27 views

Error handling in a size_t hashfunction

For school I have a big assignment on hashtables etc. One of the functions is a size_t function where we calculate the hash value. (Keep in mind the structure of every function is given so we are not ...
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0answers
32 views

Compiling an impure language into a pure stack-based language

For a personal learning and fun project, I build an abstract virtual machine based on a stack. The instructions are simple and act on the top of the stack only. There are also stack operators such as <...
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0answers
11 views

FOIL system for learning PROLOG rules from facts

I'm trying to use FOIL, a system from the 1990s developed by Ross Quinlan, to learn Prolog rules from facts. However, the input file syntax is tricky for me. Could someone provide me an example input ...
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1answer
32 views

Type inference with overloading

I am working on a type system supporting overloading. I have a rough idea of how type inference is usually implemented in such a scenario, but I am wondering how - after type inference is completed - ...
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2answers
23 views

Does hiding variables work in terms of blocks or line-by-line?

Let's assume I have the following code: declaration of a declaration of b ..a..b { ..a..b declaration of a declaration of b ..a } In this code {} ...
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0answers
23 views

≤ shown as £; ≥ shown as ³

I have a printed answer to a math problem which has weird symbols on it. I figured out that the symbols were just incorrect renderings of usual symbols. Do you know what might have caused this?
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1answer
11k views

What is the earliest use of the “this” keyword in any programming language?

I understand the this (or self or Me) is used to refer to the current object, and that it is ...
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0answers
28 views

Is Event Calculus applied for program verification?

Recently I've read wiki page about Robert Kowalski (Prolog author) and stumbled upon interesting concept of Event Calculus. The wiki article mentions only few applications of this logical language. I ...
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2answers
68 views

resource on translating imperative programs to functional programs

I'm not asking this question for the purpose of any particular project. Rather, I'm trying to understand how to translate non-trivial programs in imperative style to functional style. By functional ...

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