A functional programming language

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5
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1answer
783 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 ...
31
votes
2answers
2k views

Why did the Haskell committee choose monads to represent I/O?

The Clean language uses uniqueness types to handle I/O in a purely functional setting. Why did the Haskell committee go with monads instead? Were there other proposals for handling state that the ...
2
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2answers
304 views

Why isn't Haskell able to optimize infinite lists?

Lets say you've got a list l = [0, 2..] and you want to get the nth number when n is pretty large, say n=123456789. So you call l !! 123456789. On my machine, this results in out of memory. So why ...
22
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2answers
3k views

Why does Haskell have built-in “if/then/else” instead of defining it as a simple library function?

Why does Haskell have a built-in if/then/else, which is dependent on the Bool type, instead of having a simple library function? Such as if :: Bool -> a -> a -> a if True x _ = x if False _ ...
6
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2answers
157 views

Guidelines for returning collections from public functions

The Problem Imagine you have a function in a public API that needs to return some kind of collection. Its type is something like foo :: a -> b where b is some kind of collection. As far as I ...
2
votes
1answer
162 views

To which level Haskell's HDBC is lazy?

The HDBC documentation states: fetchAllRows :: Statement -> IO [[SqlValue]]Source Lazily fetch all rows from an executed Statement. You can think of this as hGetContents applied to a ...
1
vote
1answer
309 views

Picking a card from a shuffled deck

I'm pretty new to Haskell although I did some ML many moons ago. I'm trying to set up a deck of playing cards, shuffle them and then deal them. I have the deck and shuffle sorted (of a fashion) but ...
1
vote
1answer
246 views

What is this programming style? “Monoid-ic”?

In a moderately old blog post, Conal Elliot makes an interesting (if less than serious) argument that C is a purely functional language, by drawing a parallel between the combination of the C ...
7
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2answers
1k views

Implement Haskell typeclass with C# interface

I'm trying to compare Haskell's type classes and C#'s interfaces. Suppose there is a Functor. Haskell: class Functor f where fmap :: (a -> b) -> f a -> f b How to implement this type ...
17
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4answers
2k views

How does persistence fit into a purely functional language?

How does the pattern of using command handlers to deal with persistence fit into a purely functional language, where we want to make IO-related code as thin as possible? When implementing ...
1
vote
2answers
627 views

Why does a monad use “return” or “unit” rather than “lift”?

This is partly genuine curiosity, and partly a check on my understanding. I'm probably missing the point. In Haskell, why does a monad use operations called return or unit to describe putting a type ...
15
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6answers
711 views

Introducing functional programming into your development environment [closed]

This is a long story but I will try to summarize it as best I can. We are a .NET shop that writes software for a variety of different types of funds. For example, we write health claims management ...
35
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2answers
4k views

Misconceptions about purely functional languages?

I often encounter the following statements / arguments: Pure functional programming languages do not allow side effects (and are therefore of little use in practice because any useful program does ...
2
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2answers
512 views

Mapping a list of optional values to an optional list of values

I have encountered the following pattern while programming in Haskell (but the pattern could occur in any language supporting lists, option types, and mapping of a function over a list). I have types ...
26
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3answers
3k views

Different ways to see a monad

While learning Haskell I have faced a lot of tutorials trying to explain what are monads and why monads are important in Haskell. Each of them used analogies so it would be easier to catch the ...
4
votes
2answers
474 views

Is there any particular reason for the use of lists over queues in functional programming languages?

Most functional programming languages such as Scheme and Haskell use lists as their main data structure. Queues are identical to lists, except for the fact appending to the end - not to the begin - ...
2
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1answer
197 views

Building proprietary software over haskell compiler [closed]

Is it perfectly legal to use GHC as base and build some commercial application over its top ? Are there such examples I can can interact with ?
8
votes
2answers
1k views

Can someone explain the concept behind Haskell's memoization?

(note I'm putting the question here because it's about the conceptual mechanics of it, rather than a coding problem) I was working on a small program, that was using a sequence of fibonacci numbers ...
13
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2answers
537 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 ...
15
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2answers
441 views

Side effect-free interface on top of a stateful library

In an interview with John Hughes where he talks about Erlang and Haskell, he has the following to say about using stateful libraries in Erlang: If I want to use a stateful library, I usually build ...
1
vote
1answer
328 views

Haskell: Best tools to validate textual input?

In Haskell, there are a few different options to "parsing text". I know of Alex & Happy, Parsec and Attoparsec. Probably some others. I'd like to put together a library where the user can input ...
19
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2answers
2k 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 ...
11
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2answers
1k views

Functional programming and stateful algorithms

I'm learning functional programming with Haskell. In the meantime I'm studying Automata theory and as the two seem to fit well together I'm writing a small library to play with automata. Here's the ...
8
votes
1answer
900 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 ...
37
votes
4answers
11k views

Are there any downsides or problems with Haskell?

I'm looking at diving into Haskell for my next (relatively trivial) personal project. The reasons that I'm tackling Haskell are: Get my head into a purely functional language Speed. While I'm sure ...
23
votes
3answers
12k views

What are the advantages of using LISP and Haskell? Will they make me a better programmer? [closed]

I know Lisp and Haskell are functional and logic programming languages respectively, but what exactly does this mean? How do they differ from other languages? I've heard that learning these will make ...
1
vote
2answers
955 views

Why don't we have a non-turing complete general purpose language yet? [duplicate]

Non-turing complete languages can solve every practical problem that a turing-complete language can. Also, they are much more analyzable than turing complete languages. The compiler can comprehend the ...
11
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2answers
2k views

Haskell memory efficiency - which is the better approach?

We are implementing a matrix compression library based on a modified two dimensional grammar syntax. Now we have two approaches for our data types -which one will be better in case of memory usage? ...
0
votes
1answer
212 views

Why does this article state that graduate education liberate one from concerns like the efficiency of hardware-based integers? [closed]

Quoting The Evolution of Haskell Programmer, graduate education tends to liberate one from petty concerns about, e.g., the efficiency of hardware-based integers What exactly does this ...
8
votes
2answers
428 views

Choosing the language to build an app in based on hiring market vs performance and maintainability [closed]

I'm facing a choice of whether to start building Haskell components for a certain production app that is all done in Ruby. I'm leaning toward Haskell for several reasons, primarily speed (compiled ...
8
votes
3answers
655 views

When is it a good time to reason about performance in Haskell?

Simon Peyton Jones himself recognizes that reasoning about performance in Haskell is hard due to the non strict semantics. I have yet to write a significant project in haskell so I wonder: can I ...
8
votes
2answers
520 views

Is Haskell function composition an instance of pipe & filter architectural pattern

The pipe & filter architectural pattern is defined as a chain of processing elements, arranged so that the output of each element is the input of the next. Every example seems to consider ...
2
votes
5answers
748 views

The rationale behind Falsy values [closed]

I'm wondering what the arguments for/against Falsy values are. On what principles would you decide to add or exclude them from a language? Are there any problems you could see them causing off-hand? ...
12
votes
2answers
962 views

Functional reactive programming — is Fay expressive enough?

So I'm doing a fairly involved javascript/html client with lots of ajax calls and other involvements of callback-ism. I'm entertaining the thought of using Fay for this purpose. I'm aware of Elm. ...
8
votes
2answers
2k views

Could we build a functional computer?

As mush as FP has done, in the end, all our programs are structured. That is, it doesn't matter how pure or functional we make a them - they are always translated to assembly, so what actually runs ...
1
vote
1answer
798 views

Modern REPL for Haskell - is anybody working on it? [closed]

It's time Haskell had a modern REPL like Mathematica's (or better). Make each calculation run in a separate thread, so user has control over each computation box's resources (ability to pause, play, ...
-1
votes
1answer
127 views

Exclude the zero in the given data in Haskell [closed]

I have a list of integers. Also, I have a function which returns True when the element is non-zero, and returns False when the element is zero (let's call it FUNCTION1). So, how to define another ...
9
votes
1answer
462 views

Necessity to learn haskell language extension for production

Haskell core language is really simple. Coming from an OO background, the main difficulty is to adapt to the pure functional paradigm. While learning "basic" Haskell, I have always considered ...
7
votes
2answers
1k views

Is Haskell/Clojure actually unsuited for dynamic systems such as particle simulation?

I've been told in previous questions that functional programming languages are unsuited for dynamic systems such as a physics engine, mainly because it's costly to mutate objects. How realistic is ...
10
votes
9answers
2k views

Resources for improving your comprehension of recursion? [closed]

I know what recursion is (when a patten reoccurs within itself, typically a function that calls itself on one of its lines, after a breakout conditional... right?), and I can understand recursive ...
17
votes
1answer
824 views

What's the progress on Haskell records?

Recently I stumbled once again on the issues of Haskells records, in particular the uniqueness of field names (it's a pain ...) I already read A proposal for records in Haskell from SPJ and Greg ...
7
votes
2answers
363 views

Why have a wrapper constructor when storing a function in a data type?

I can never do too many Haskell tutorials. There is always something to refine and learn. So, I am working through chapter 10 of Real World Haskell, and everything makes sense. but Why do newtype ...
8
votes
2answers
1k views

Inspirational software for end-users written in Haskell? [closed]

I think great technology is invisible. Besides the usual suspects (GHC, Xmonad, proprietary trading software) what great examples are there of end-user software written in Haskell? I think good ...
3
votes
1answer
309 views

Erlang/Haskell web service to server files [closed]

I have across a thread mentioning that Erlang would not be suited for a web application serving files. I was curious whether anyone had any experience building such webservice with erlang? Would ...
2
votes
1answer
281 views

Good serialization solution for communication between Python AND Haskell programs? [closed]

I found this: http://msgpack.org/ But.. I've never used it, so I don't know what whether it is much good. Anybody has proposals? Basic requirements: serialize as many data structures used ...
8
votes
2answers
373 views

Who first coined the term Higher Order Function and/or First Class Citizen?

I've come to understand that long before Haskell, O'Caml or LISP, higher order functions were an academic research subject and in mathematics, Schönfinkel (in 1967) and Haskell Curry (in 1968) already ...
7
votes
2answers
473 views

What's a good math textbook to have on my desk while studying Haskell? [closed]

I just started learning Haskell and it seems like you can't get too far in the language without being comfortable ( or at least exposed ) to certain branches of mathematics. Unfortunately I have major ...
12
votes
6answers
7k views

Which self balancing binary tree would you recommend?

I'm learning Haskell and as an exercise I'm making binary trees. Having made a regular binary tree, I want to adapt it to be self balancing. So: Which is most efficient? Which is easiest to ...
16
votes
1answer
1k 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 ...