In Go, arrays are inflexible (because their length is encoded in their type) and costly to pass to functions (because a function operates on copies of its array arguments). I’m assuming you’d like to operate on slices rather than on arrays. Because methods cannot take additional type arguments, you cannot simply declare a generic Map … Read more
It appears I cannot use an if statement. Arrow functions either allow to use an expression or a block as their body. Passing an expression foo => bar is equivalent to the following block foo => { return bar; } However, if (person.age > 18) person is not an expression, if is a statement. Hence … Read more
Yes, this is possible. myfunc can call the passed-in function like: def myfunc(anotherfunc, extraArgs): anotherfunc(*extraArgs) Here is a fully worked example: >>> def x(a, b): … print(‘a:’, a, ‘b:’, b) … >>> def y(z, t): … z(*t) … >>> y(x, (‘hello’, ‘manuel’)) a: hello b: manuel
A wonderful opportunity to learn about mutual recursion. The input can be in any order – function makeIndex (items, indexer) { const append = (r, k, v) => r.set(k, (r.get(k) || []).concat([ v ])) return items.reduce ( (r, i) => append(r, indexer(i), i) , new Map ) } function makeTree (index, root = null) { … Read more
You can do the following using array_map: $new_arr = array_map(‘trim’, explode(‘,’, $str));
There is some structure to this problem, and here it comes. I’ll be using this stuff: import Control.Applicative import Data.Traversable import Data.List First up, lists-with-padding are a useful concept, so let’s have a type for them. data Padme m = (:-) {padded :: [m], padder :: m} deriving (Show, Eq) Next, I remember that the … Read more
This can’t be done generically over all MonadIO instances because of the IO type in a negative position. There are some libraries on hackage that do this for specific instances (monad-control, monad-peel), but there’s been some debate over whether they are semantically sound, especially with regards to how they handle exceptions and similar weird IOy … Read more
That should do it: def repeated(f, n): def rfun(p): return reduce(lambda x, _: f(x), xrange(n), p) return rfun def square(x): print “square(%d)” % x return x * x print repeated(square, 5)(3) output: square(3) square(9) square(81) square(6561) square(43046721) 1853020188851841 or lambda-less? def repeated(f, n): def rfun(p): acc = p for _ in xrange(n): acc = f(acc) … Read more
Yes, that’s para. Compare with catamorphism, or foldr: para :: (a -> [a] -> b -> b) -> b -> [a] -> b foldr :: (a -> b -> b) -> b -> [a] -> b para c n (x : xs) = c x xs (para c n xs) foldr c n (x : … Read more
Can a Python function be an argument of another function? Yes. def myfunc(anotherfunc, extraArgs): anotherfunc(*extraArgs) To be more specific … with various arguments … >>> def x(a,b): … print “param 1 %s param 2 %s” % (a,b) … >>> def y(z,t): … z(*t) … >>> y(x, (“hello”,”manuel”)) param 1 hello param 2 manuel