There’s no way I know of within the expression of the anonymous function to have it select which output to return from a function with multiple possible output arguments. However, you can return multiple outputs when you evaluate the anonymous function. Here’s an example using the function MAX: >> data = [1 3 2 5 … Read more
You can use the use keyword to inherit variables from the parent scope. In your example, you could do the following: $callback = function($val) use ($avg) { return $val < $avg; }; For more information, see the manual page on anonymous functions. If you’re running PHP 7.4 or later, arrow functions can be used. Arrow … Read more
Fortran doesn’t support anonymous functions. The simple work around is to write a function that has a name. There are then two possible approaches in modern Fortran for capturing the value of any additional parameters required for the function beyond the variable being minimised: The procedure to be minimised is expressed as a deferred binding … Read more
#(println “Hello, world!”) -> no arguments #(println (str “Hello, ” % “!”)) -> 1 argument (% is a synonym for %1) #(println (str %1 “, ” %2 “!”)) -> 2 arguments and so on. Note that you do not have to use all %ns, the number of arguments expected is defined by the highest n. … Read more
What you are after is called partial function application. Don’t be fooled by those that don’t understand the subtle difference between that and currying, they are different. Partial function application can be used to implement, but is not currying. Here is a quote from a blog post on the difference: Where partial application takes a … Read more
Nope, sorry. That would require generic fields or generic properties, which are not features that C# supports. The best you can do is make a generic method that introduces T: public Func<IList<T>, T> SelectionMethod<T>() { return list => list.First(); } And now you can say: Func<IList<int>, int> selectInts = SelectionMethod<int>();
The use of “use” is correct in this case too. With closures, to access variables that are outside of the context of the function you need to explicitly grant permission to the function using the use function. What it means in this case is that you’re granting the function access to the $tax and $total … Read more
For the record, a.map(_) does not work because it stands for x => a.map(x), and not a.map(x => x). This happens because a single _ in place of a parameter stands for a partially applied function. In the case of 2*_, that stands for an anonymous function. These two uses are so close that is … Read more
In PHP, methods and properties are in a separate namespace (you can have a method and a property with the same name), and whether you are accessing a property or a method depends of the syntax you are using to do so. $expr->something() is a method call, so PHP will search something in the class’ … Read more
In order for it to work, you need to pass $factorial as a reference $factorial = function( $n ) use ( &$factorial ) { if( $n == 1 ) return 1; return $factorial( $n – 1 ) * $n; }; print $factorial( 5 );