Questions tagged [type-systems]

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1answer
419 views

Language with extensible type system?

Is there a practical programming language that has an extensible type system? Or alternatively, an add-on type system that can be used with existing languages? With extensible I mean that the typing ...
5
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1answer
122 views

Extending simple types to allow `fix`

I'm reading some lecture notes saying that “fix cannot be defined in the simply typed lambda-calculus” and that “no expression that can lead to non-terminating ...
16
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2answers
2k views

What parts of homotopy type theory are not possible in Agda or Coq?

When we look at the book, Homotopy Type Theory - we see the following topics: ...
11
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2answers
2k views

Is compiler for dependent type much harder than an intepreter?

I have been learning something about implementing dependent types, like this tutorial, but most of them is implementing interpreters. My question is, it seems that implementing a compiler for ...
1
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1answer
111 views

Type, operation and function, and their limits

First of all, sorry for my English. I would like to know, when I want to define a new type (I'm currently developing a computer interpreted language), how can I determine which "functions" are ...
6
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1answer
191 views

Typing relations terminology – how do I read typing relations?

I am currently trying to read up on type theory and have some quick questions on terminology. In the following rule, $$ \frac{x:T_1 \vdash t_2 : T_2}{\vdash \lambda x:T_1.t_2:T_1\to T_2} $$ How ...
7
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1answer
748 views

Constraint types (IBM/X10) compared to dependent types

Constraint types have been proposed by IBM in their X10 programming language (it's a commercial programming language, not open source software). Nystrom, Nathaniel, et al. "Constrained types for ...
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0answers
85 views

Semantics of a programming language [duplicate]

A newbie question, if I may... Could you be so kind and explain to me in plain english meaning of 'denotational semantics' and 'operational semantics'? I'm familiar with the definitions and have read ...
4
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0answers
190 views

Type-and-effect systems, stochasticism and effect squelching: how about quicksort?

There's a feature of Haskell's type system which bugs me: you can't implement a randomized sorting algorithm without the use of randomness spilling out into all of its callers. That seems undesirable....
5
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0answers
256 views

Commonalities and differences between canonical structures and the implicit calculus

There is a paper on The Implicit Calculus as a generalization of type classes. Coq's canonical structures are also a generalization of type classes. The paper does not mention canonical structures ...
8
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2answers
676 views

Free theorems, where?

I've found this webapp which lets you generate a free theorem for a given type. The generated theorems quantify over types and relations on these types. These theorems (formulas) are theorems of ...
0
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1answer
131 views

How to generalize a map of type for many operators?

I am formalizing the type system for a small language, and thus writing inference rules. Taking unary - operator for example, its entry may be a number as well as ...
14
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1answer
984 views

A mathematical (categorical) description of type classes

A functional language can be viewed as a category where its objects are types and morphisms functions between them. How do type classes fit in this model? I assume we should only consider those ...
9
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1answer
443 views

What are possible implementations of Haskell's type classes and what are their (dis)advantages?

As far as I know, a Haskell function with type classes constraints is internally compiled to a function with additional arguments that receive dictionaries with the necessary implementations of each ...
4
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1answer
282 views

Classes and types in object-oriented languages

In typical object-oriented programming languages like Java, classes are used as types. On the other hand, type-theoretic approaches to object-oriented languages treat interfaces as types. Are there ...
10
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2answers
817 views

Ownership types and Separation Logic

Ownership types and Separation Logic seem to have similar goals, control over ownership and aliasing. Perhaps, I should also add: the ability to write modular specifications. What is known about the ...
8
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1answer
328 views

Proofs techniques related to Curry–Howard correspondence

I am looking for sources about formalized notion of programs. This seems to be closely related to Curry-Howard correspondence, but one could also track this back to Universal Turing Machines and its ...
15
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4answers
588 views

Unary parametricity vs. binary parametricity

I've recently become quite interested in parametricity after seeing Bernardy and Moulin's 2012 LICS paper ( https://dl.acm.org/citation.cfm?id=2359499). In this paper, they internalize unary ...
6
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1answer
269 views

Forms of types in the calculus of constructions

In the usual presentations of the calculus of constructions (CC) with two kinds Prop and Type such that Prop:Type and impredicative on Prop, it is easy to show the following result: every closed term ...
15
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1answer
3k views

How does inheritance differ from subtyping?

In programming language perspective, what is mean by subtyping? I heard that "Inheritance is not Subtyping". Then what are the differences between inheritance and subtyping?
11
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3answers
1k views

Type system based on naive set theory

As I understand, in computer science data types are not based on set theory because of things like Russell's paradox, but as in real world programming languages we can't express such complex data ...
33
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3answers
2k views

Type classes vs object interfaces

I don't think I understand type classes. I'd read somewhere that thinking of type classes as "interfaces" (from OO) that a type implements is wrong and misleading. The problem is, I'm having a problem ...
9
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2answers
326 views

Research on call-site based type inference?

I'm trying to learn more about whole-program type checking and type inferencing systems that use information from function call sites to compute type information (in addition to the standard approach ...
5
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2answers
392 views

the type system does not tell the whole story due to “exception”

I am wondering whether it is a bad style to use "exception". For example, in Ocaml, the exception does not appear as the .mli file. So it appears to me that "exception" is something that cannot be ...

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