Anonymous function
In computer science and mathematics, an anonymous function is a function with no name. Usually, a function is written like: . It can be written anonymously as . Anonymous functions exist in most functional programming languages and most other programming languages where functions are values.
Examples in some programming languages
Each of these examples show a nameless function that multiplies two numbers.
Python
Uncurried (not curried):
(lambda x, y: x * y)
Curried:
(lambda x: (lambda y: x * y))
</source>
When given two [[Number|numbers]]:
<syntaxhighlight lang="python">
>>>(lambda x: (lambda y: x * y)) (3) (4)
12
</source>
===Haskell===
Curried:<syntaxhighlight lang="haskell">
\x -> \y -> x * y
</source><syntaxhighlight lang="haskell">
\x y -> x * y
When given two numbers:
>>> (\x -> \y -> x * y) 3 4
12
</source>
The function can also be written in [[point-free|point-free (tacit)]] style:
<syntaxhighlight lang="haskell">
(*)
</source>
===Standard ML===
Uncurried:
<syntaxhighlight lang="sml">
fn (x, y) => x * y
</source>
Curried:
<syntaxhighlight lang="sml">
fn x => fn y => x * y
</source>Point-free:<syntaxhighlight lang="sml">
(op *)
JavaScript
Uncurried:
(x, y) => x * y
function (x, y) {
return x * y;
}
Curried:
x => y => x * y
function (x) {
return function (y) {
return x * y;
};
}
</source>
===Scheme===
Uncurried:<syntaxhighlight lang="scheme">
(lambda (x y) (* x y))
Curried:
(lambda (x) (lambda (y) (* x y)))
</source>Point-free:<syntaxhighlight>
*
C++ 11
Uncurried: <syntaxhighlight lang="cpp"> [](int x, int y)->int { return x * y; }; </source> Curried: <syntaxhighlight lang="cpp"> [](int x) { return [=](int y)->int { return x * y; }; }; </source>
C++ Boost
Uncurried:<syntaxhighlight lang="cpp"> _1 * _2 </source> Note: What you need to write boost lambda is to include <boost/lambda/lambda.hpp> header file, and using namespace boost::lambda, i.e. <syntaxhighlight lang="cpp">
- include <boost/lambda/lambda.hpp>
using namespace boost::lambda; </source>
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