In c# it's possible to create a list of functions like so: var myList = new List< Func<Foo> >(); This will allow functions (delegates) that take no arguments and return a value of type Foo to be added to the list. So something like: Foo myFunc1() { ... } would be a valid member of that list. My question is, how do I declare the typ...
Do functional languages bring anything in the resolution of everyday business problems? Are there any successful projects that have been implemented using a functional language (ideally with a published test case)? ...
I'm thinking about writing a Delphi implementation of the functional Zip routine, which takes two lists and outputs a list of pairs of elements. So, feeding it [1, 2, 3] and ['a', 'b', 'c'] would give [(1, 'a'), (2, 'b'), (3, 'c')] as the result. Which is great if both inputs are exactly the same length, like they are in every demo I'v...
I'm looking at OCaml's functors. It looks to me pretty identical to the so called generic objects in C++/C#/Java. If you ignore Java's type erasion for now, and ignore the implementation details for C++ templates (I'm interested with the language feature), functors are quite indentical to generics. If I understand it correctly, functor g...
I am reading this tutorial on Haskell. They define function composition as the following: (.) :: (b->c) -> (a->b) -> (a->c) f . g = \ x -> f (g x) No examples were provided, which I believe would enlighten me as to what is being defined here. Can someone provide a simple example (with explanation...
My answer for a recent question about GOTOs and tail recursion was phrased in terms of a call stack. I'm worried that it wasn't sufficiently general, so I ask you: how is the notion of a tail call (or equivalent) useful in architectures without a call stack? In continuation passing, all called functions replace the calling function, and...
Hello. I am attempting to build a rudimentary interpreter in Scheme, and I want to use an association list to map to arithmetic functions. This is what i have so far: ; A data type defining an abstract binary operation (define binoptable '(("+" . (+ x y))) ("-" . (- x y)) ("*" . (* x y)) ("/" . (/ x y))) ) The problem is...
Hi I am a newbie in the Erlang world. When I think of how we need to solve the following problem (and there are a long list of similar ones), I think it's really inefficient because we are speaking of a lot of recursion. Apprently, language like C/Java would not need the clumsy recursion to solve this problem, but with Erlang (I guess ot...
I am new to Scheme Macros. If I just have one pattern and I want to combine the define-syntax and syntax-rules, how do I do that? (define-syntax for (syntax-rules (from to) [(for i from x to y step body) ...] [(for i from x to y body) ...])) If I just have one for, how do I combine the syntax definition and the rule? Thanks...
I just wondered how it is possible to write a user-defined square root function (sqrt) in a way that it interacts properly with F#'s unit system. What it should be like: let sqrt (x : float<'u ^ 2>) = let x' = x / 1.0<'u ^ 2> // Delete unit (x ** 0.5) * 1.0<'u> // Reassign unit But this is disallowed due to nonzero const...
In the chapter about function in the Oz tutorial, it says that: similar to lazy functional languages Oz allows certain forms of tail-recursion optimizations that are not found in certain strict functional languages including Standard ML, Scheme, and the concurrent functional language Erlang. However, standard function d...
When learning about new programming subjects I usually follow a pattern: I read about it, I understand it, and then I code up a few examples to make sure I really get it. I've read a lot about monads, and I'm confident that I understand and get them. I'm now at a stage where I'd really like to code up a few monads to solidify my under...
What are your favourite short, mind-blowing snippets in functional languages? My two favourite ones are (Haskell): powerset = filterM (const [True, False]) foldl f v xs = foldr (\x g a -> g (f a x)) id xs v -- from Hutton's tutorial (I tagged the question as Haskell, but examples in all languages - including non-FP ones - are welco...
Hello, What are some other language independent ways of designing recursive functions other than the typical: if (counter < 1) return output; else callSelf(); Do other methods even exist? Whenever viewing examples I always see a version of the code above. Thanks! :) ...
Which functional programming languages have bioinformatics libraries easily available? (Don't include multi-paradigm languages such as Ruby) Update: Listing which major functional programming languages don't currently have easy access to bioinformatics libraries is also welcome. ...
I'm playing with scala's distributed actors. Very nice. I have a server which executes incoming function objects. For example, the client has object Tasks { def foo = {Console.println("I am Foo")}; def bar = {Console.println("I am Bar");} } // In client actor... ... server ! Tasks.foo _ ... And the server can pick these up an...
Even looking closely over documentation on Clojure, I do not see any direct confirmation as to whether or not Clojure supports operator overloading. If it does, could someone provide me with a quick snipplet of how to overload, let's say, the "+" operator to delegate to some predefined method that we can call myPlus. I am very new to C...
How good is 'pure' functional programming for basic routine implementations, e.g. list sorting, string matching etc.? It's common to implement such basic functions within the base interpreter of any functional language, which means that they will be written in an imperative language (c/c++). Although there are many exceptions.. At leas...
What would you name a function that takes a list and a function, and returns True if applying the function to all elements gives the same result? def identical_results(l, func): if len(l) <= 1: return True result = func(l[0]) for el in l[1:]: if func(el) != result: return False return True Is there ...
The workflow is simple: You click inside a textarea. The text is copied to the client's clipboard. Display notice to the user. How do you do it? ...