This has nothing to do with functools.partial, really. You are essentially calling your function like this: f(1, x=3) Python first fulfils the positional arguments, and your first argument is x. Then the keyword arguments are applied, and you again supplied x. functools.partial() has no means to detect that you already supplied the first positional argument … Read more
functools.partial returns a callable wrapping a function with some or all of the arguments frozen. import sys import functools print_hello = functools.partial(sys.stdout.write, “Hello world\n”) print_hello() Hello world The above usage is equivalent to the following lambda. print_hello = lambda *a, **kw: sys.stdout.write(“Hello world\n”, *a, **kw)
Java 8 (released March 18th 2014) does support currying. The example Java code posted in the answer by missingfaktor can be rewritten as: import java.util.function.*; import static java.lang.System.out; // Tested with JDK 1.8.0-ea-b75 public class CurryingAndPartialFunctionApplication { public static void main(String[] args) { IntBinaryOperator simpleAdd = (a, b) -> a + b; IntFunction<IntUnaryOperator> curriedAdd = … Read more
@Aadit, I’m posting this because you shared a comment on my answer to To “combine” functions in javascript in a functional way? I didn’t specifically cover currying in that post because it’s a very contentious topic and not really a can of worms I wanted to open there. I’d be wary using the phrasing “how … Read more
It makes you able to do e.g.: scala> def foo(as: Int*)(bs: Int*)(cs: Int*) = as.sum * bs.sum * cs.sum foo: (as: Int*)(bs: Int*)(cs: Int*)Int scala> foo(1, 2, 3)(4, 5, 6, 7, 9)(10, 11) res7: Int = 3906
For languages that support currying and partial-application easily, there is one compelling series of arguments, originally from Chris Okasaki: Put the data structure as the last argument Why? You can then compose operations on the data nicely. E.g. insert 1 $ insert 2 $ insert 3 $ s. This also helps for functions on state. … Read more
Simple rules to determine the scope of underscore: If the underscore is an argument to a method, then the scope will be outside that method, otherwise respective the rules below; If the underscore is inside an expression delimited by () or {}, the innermost such delimiter that contains the underscore will be used; All other … Read more
No According to the documentation, partial cannot do this (emphasis my own): partial.args The leftmost positional arguments that will be prepended to the positional arguments You could always just “fix” pow to have keyword args: _pow = pow pow = lambda x, y: _pow(x, y)
I would do it this way: Write a parameter-replacer expression-visitor that manipulates the original expression as follows: Gets rid of the parameter you don’t want entirely from the lambda signature. Replaces all uses of the parameter with the desired indexer expression. Here’s a quick and dirty sample I whipped up based on my earlier answer … Read more
Strictly speaking, this is not a curried function, but a method with multiple argument lists, although admittedly it looks like a function. As you said, the multiple arguments lists allow the method to be used in the place of a partially applied function. (Sorry for the generally silly examples I use) object NonCurr { def … Read more