Tagged Questions
132
votes
4answers
10k views
What is the difference between a 'closure' and a 'lambda'?
Could someone explain? I understand the basic concepts behind them but I often see them used interchangeably and I get confused.
And now that we're here, how do they differ from a regular function?
26
votes
14answers
3k views
What are some interesting uses of higher-order functions?
I'm currently doing a Functional Programming course and I'm quite amused by the concept of higher-order functions and functions as first class citizens. However, I can't yet think of many practically ...
24
votes
8answers
3k views
19
votes
4answers
2k views
Haskell: How to compose `not` with a function of arbitrary arity?
When I have some function of type like
f :: (Ord a) => a -> a -> Bool
f a b = a > b
I should like make function which wrap this function with not.
e.g. make function like this
g :: ...
18
votes
5answers
2k views
Why are “pure” functions called “pure”?
A pure function is one that has no side effects -- it cannot do any kind of I/O and it cannot modify the state of anything -- and it is referentially transparent -- when called multiple times with the ...
14
votes
4answers
515 views
In C, what is the difference between `&function` and `function` when passed as arguments?
For example:
#include <stdio.h>
typedef void (* proto_1)();
typedef void proto_2();
void my_function(int j){
printf("hello from function. I got %d.\n",j);
}
void call_arg_1(proto_1 arg){
...
12
votes
3answers
2k views
OCaml: What is the different between `fun` and `function` keywords?
Sometimes I see code like
let (alt : recognizer -> recognizer -> recognizer) =
fun a b p -> union (a p) (b p)
Or like:
let hd = function
Cons(x,xf) -> x
| Nil -> raise ...
11
votes
7answers
304 views
can if be a proper function rather than a special form
I finally started learning functional languages (emacs lisp) and it makes explicit distinction between functions and special forms such as flow control , for example if.
Is there a ...
10
votes
4answers
583 views
In Haskell, + is a function, (+ 2) is a function, (+ 2 3) is 5. What exactly is going on there?
How is this possible, what is going on there?
Is there a name for this?
What other languages have this same behavior?
Any without the strong typing system?
9
votes
6answers
2k views
Haskell function composition
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 ...
9
votes
6answers
385 views
Is there a name for a function that takes a piece of data and a list of functions and applies each function to the result of the last one?
Clojure has a macro, ->, which takes a piece of data and a bunch of functions, applies the data to the first function, and then applies the result of that to the next one, the result of that to the ...
9
votes
1answer
133 views
Is it good practice for a Clojure record to implement IFn?
Suppose I have a record that is "function-like", at least in the sense that it represents an operation that could be applied to some arguments.
I can make it work as a function by implementing ...
8
votes
2answers
816 views
When is a scala partial function not a partial function?
While creating a map of String to partial functions I ran into unexpected behavior. When I create a partial function as a map element it works fine. When I allocate to a val it invokes instead. ...
8
votes
1answer
1k views
compose function and functional module
Python 3.2 documentation refers to Collin Winter's functional module which contains function compose:
The compose() function implements function composition. In other
words, it returns a wrapper ...
7
votes
8answers
545 views
In which languages is function abstraction not primitive
In Haskell function type (->) is given, it's not an algebraic data type constructor and one cannot re-implement it to be identical to (->).
So I wonder, what languages will allow me to write my ...
