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1
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1answer
165 views

What is the evidence that an API has exceeded its orthogonality in the context of types?

Wikipedia defines software orthogonality as: orthogonality in a programming language means that a relatively small set of primitive constructs can be combined in a relatively small number of ways ...
0
votes
1answer
57 views

Is there any practical use for the empty type in Common Lisp?

The Common Lisp spec states that nil is the name of the empty type, but I've never found any situation in Common Lisp where I felt like the empty type was useful/necessary. Is it there just for ...
2
votes
1answer
91 views

Interface hierarchy design for separate domains

There are businesses and people. People could be liked and businesses could be commented on: class Like class Comment class Person implements iLikeTarget class Business implements iCommentTarget ...
48
votes
5answers
4k views

How do languages with Maybe types instead of nulls handle edge conditions?

Eric Lippert made a very interesting point in his discussion of why C# uses a null rather than a Maybe<T> type: Consistency of the type system is important; can we always know that a ...
4
votes
1answer
365 views

Is there an imperative language with a Haskell-like type system? [closed]

I've tried to learn Haskell a few times over the last few years, and, maybe because I know mainly scripting languages, the functional-ness of it has always bothered me (monads seem like a huge mess ...
2
votes
3answers
256 views

If Scheme is untyped, how can it have numbers and lists?

Scheme is said to be just an extension of the Untyped Lambda Calculus (correct me if I am wrong). If that is the case, how can it have Lists and Numbers? Those, to me, look like 2 base types. So I'd ...
10
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4answers
760 views

Type systems: nominal vs. structural, explicit vs. implicit

I'm a bit confused about the difference between nominal and structural type systems. Can someone please explain how they differ? From what I understand: Nominal: Type compatibility is based on type ...
6
votes
0answers
141 views

Using uniqueness types to implement safe parallelism

I've been interested in uniqueness types as an alternative to monads in pure functional languages for some time; unfortunately, this is kind of an esoteric area of CS research and online resources ...
15
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9answers
17k views

Type Casting variables in PHP: Is there a practical example?

PHP, as most of us know, has weak typing. For those who don't, PHP.net says: PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined ...
17
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4answers
3k views

Why does Java not do type inference?

I have always wondered why Java does not do type inference given that the language is what it is, and its VM is very mature. Google's Go is an example of a language with excellent type inference and ...
2
votes
1answer
349 views

static languages or dynamic languages? [closed]

What is the exact border between the static and dynamic languages? I mean I am told the following parameters are the deciding factors: Compilation or interpretation Typing Runtime generation Dynamic ...
0
votes
1answer
54 views

Would it make sense to add parameters of an inferred type to inheritance?

I'll write this in PHP (where this thought originated), but this is generic to any object-orientated language. Basically, this is an addition to abstract classes that defines the implementation of its ...
4
votes
2answers
297 views

Nulls in every type and checked exceptions in Java?

I know that null being added to every type in Java is a source of much frustration regarding the language's type system. At the same time I generally hear complaining about checked exceptions - that ...
6
votes
3answers
360 views

Are there programming languages that allow you to do set arithmetic on types?

Out of curiosity, are there languages that allow you to do set arithmetic on types to create new types? Something like: interface A { void a(); void b(); } interface B { void b(); void ...
0
votes
1answer
186 views

Can we say that Java or C# have unified inheritance trees?

Can we say that Java or C# are OO languages with a unified inheritance tree/unified type system? By unified inheritance tree/unified type system I mean that every class derives implicitly or ...
42
votes
6answers
3k views

Dynamically vs Statically typed languages studies

Do there exist studies done on the effectiveness of statically vs dynamically typed languages? In particular: Measurements of programmer productivity Defect Rate Also including the effects of ...
39
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8answers
3k views

What are the safety benefits of a type system?

In JavaScript: The Good Parts by Douglas Crockford, he mentions in his inheritance chapter, The other benefit of classical inheritance is that it includes the specification of a system of types. ...
10
votes
2answers
394 views

Are types erased in Haskell?

Haskell has a notion of “generic functions” that has some apparent similarity with common lisp—having neither experience with Haskell nor with common lisp, I might be very approximative here. This ...
7
votes
3answers
350 views

Is changing the type of a variable partway through a procedure in a dynamically typed language bad style?

In Python (and occasionally PHP) where variables do not have fixed types, I'll frequently perform 'type transformations' on a variable part-way through my code's logic. I'm not (necessarily) talking ...
7
votes
2answers
190 views

Definition of a type

Conceptually, I used to think of types as sets. However, I think I've seen people wishing to distinguish types A, B even if they represent identical collections of values. So I figured a better ...
18
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2answers
872 views

Type checking and recursive types (Writing the Y combinator in Haskell/Ocaml)

When explaining the Y combinator in the context of Haskell, it's usually noted that the straight-forward implementation won't type-check in Haskell because of its recursive type. For example, from ...
5
votes
1answer
516 views

Maths needed to understand theory behind Haskell's type system?

Recently, I've become deeply interested in Haskell. While attempting to learn new concepts (e.g. the forall keyword and ST monad) and Haskell's type system in general, I continually run into ...
47
votes
5answers
6k views

What can Haskell's type system do that Java's can't and vice versa?

I was talking to a friend about the differences between the type systems of Haskell and Java. He asked me what Haskell's could do that Java's couldn't, and I realized that I didn't know. After ...
2
votes
3answers
299 views

Can compilers check whether certain axioms hold for a user defined type?

Suppose the following type is defined (C++ syntax, can be conceptually applied to any statically typed language.) class T { int val; friend bool operator<(const T& lhs, const T& rhs) ...
7
votes
3answers
963 views

Generics and Type-erasure

Generics in Java are implemented using type erasure. The JLS says that the inspiration was backward compatibility. Where as on the other hand C# generics are reifiable. Theoretically what are the ...
9
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0answers
169 views

Why does OCaml's (and F#'s) type inference algorithm need tagging functions as recursive? [duplicate]

From Real World OCaml (beta): OCaml distinguishes between non-recursive definitions (using let) and recursive definitions (using let rec) largely for technical reasons: the type-inference ...
3
votes
1answer
202 views

When writing an interpreter, how should the type inference algorithm change the parsed AST? Should it?

When writing an interpreter, how should the type inference algorithm chance the parsed AST? Should it? Or parsing and inference are done necessarily simultaneously? I have implemented a strongly ...
0
votes
1answer
135 views

Formal definition of “concepts / type system” for parametric types - Where to start?

I would be interested in formally defining (and consequently demonstrating) a "type system" for, well, a type system. More specifically, I would like to explore the idea of what C++ calls concepts for ...
15
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5answers
1k views

Would it make sense to use objects (instead of primitive types) for everything in C++?

During a recent project I've been working on, I've had to use a lot of functions that kind of look like this: static bool getGPS(double plane_latitude, double plane_longitude, double plane_altitude, ...
25
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9answers
3k views

Do dynamic typed languages deserve all the criticism? [closed]

I have read a few articles on Internet about programming language choice in the enterprise. Recently many dynamic typed languages have been popular, i.e. Ruby, Python, PHP and Erlang. But many ...
13
votes
1answer
571 views

Why doesn't Haskell have type-level lambda abstractions?

Are there some theoretical reasons for that (like that the type checking or type inference would become undecidable), or practical reasons (too difficult to implement properly)? Currently, we can ...
18
votes
2answers
4k views

Type inference in Java 8

Is the introduction of the new lambda notation (see e.g. this article) in Java 8 going to require some kind of type inference? If so, how will the new type system impact the Java language as a whole? ...
16
votes
1answer
2k views

Motivation and pitfalls (?) of the auto keyword in C++11

I was recently wondering why the keyword auto was chosen in C++11 to mark a variable whose type must be inferred by the compiler, like in auto x = 1; Since var seems more common in other ...
1
vote
1answer
303 views

What does “polyadic” mean in the context of functional programming and type systems?

And how does it (or does not) correspond to "polymorphic"? Occasionally I see this notion like in: Implement and represent polyadic operations. I checked Wiktionary but it only gives a general ...
5
votes
1answer
339 views

Why do generics in Scala have erased types, and are not reifiable?

Why do generics in Scala have erased types, and are not reifiable? Is it due to lack of support from the JVM or for compatibility with Java libraries? What are the advantages in general of having ...
28
votes
12answers
3k views

Is Haskell's type system an obstacle to understanding functional programming?

I'm studying Haskell for the purpose of understanding functional programming, with the expectation that I'll apply the insight that I gain in other languages (Groovy, Python, JavaScript mainly.) I ...
10
votes
7answers
973 views

Which statically typed languages support intersection types for function return values?

Initial note: This question got closed after several edits because I lacked the proper terminology to state accurately what I was looking for. Sam Tobin-Hochstadt then posted a comment which ...
14
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5answers
4k views

What arguments are there in favor of weak typing?

This came up in a discussion with a friend, and I found myself hard-pressed to think up an any good arguments. What benefits do weak typing confer?
11
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9answers
3k views

Why are inheritance and polymorphism so widely used?

The more I learn about different programming paradigms, such as functional programming, the more I begin to question the wisdom of OOP concepts like inheritance and polymorphism. I first learned ...
6
votes
2answers
2k views

Duck checker in Python: does one exist?

Python uses duck-typing, rather than static type checking. But many of the same concerns ultimately apply: does an object have the desired methods and attributes? Do those attributes have valid, ...
8
votes
10answers
1k views

Mission critical embedded language

Maybe the question sounds a bit strange, so I'll explain a the background a little bit. Currently I'm working on a project at y university, which will be a complete on-board software for an ...
7
votes
3answers
2k views

Is there a difference between casting and converting types in imperative programming languages?

The question came up in a discussion at StackOverflow. Is there a clean distinction between the two concepts cast and convert (concerning the type of an object), or are these two words describing ...
17
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24answers
1k views

Interesting or unique types in programming languages? [closed]

We have all seen integer, floating point, string, and the occasional decimal type. What are some of the most strange or unique or useful types you have encountered, useful or not?
10
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3answers
715 views

How do existential types differ from interfaces?

Given the existential type T = ∃X.{op₁:X, op₂:X→boolean} and this generic Java interface: interface T<X> { X op₁(); boolean op₂(X something); } What are the fundamental differences ...
6
votes
2answers
360 views

Values, types, kinds, and…?

We all know what a value is. A type is the type of a value. A kind is (loosely) the type of a type. A type constructs a value; a kind constructs a type. So what is the type of a kind, a thing that ...
11
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1answer
660 views

(Dis-)advantages of structural typing

I’ve just watched this talk by Daniel Spiewak where he talks about the advantages of structural typing as compared to Scala’s ans Java’s nominal typing. One example for this difference would be the ...
16
votes
6answers
6k views

Is hungarian notation a workaround for languages with insufficiently-expressive (i.e. Haskell-style) static typing?

Edit To be clear, I'm not talking about annotation variable names with the data type, but rather with information about the meaning of the variable in the context of the program. For example, a ...
0
votes
4answers
574 views

About languages strongly typed with late binding, do they make sense?

I never learnt anything about VB6 (and I dont want to) but I wanted to search for bad things in computer software, so my first though was VB6. So for example, VB6 was strongly typed with late ...
1
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4answers
395 views

Teaching programmer looking for a simple statically and weakly typed language

I'm trying to illustrate the differences between the four different type systems -- static vs. dynamic typing and weak vs. strong typing. Dynamic + weak = JavaScript Dynaimc + strong = Python ...
3
votes
1answer
519 views

C# type system and dynamic type

I'm writing a paper about the C# (and Go) type system with focus on the dynamic aspect. Does anybody have suggestions for papers/literature? The things I found don't go much into detail. I would ...