This syntax gives Kotlin great DSL capabilities, it makes functions look like language constructions. For example: with(car) { startUp() goToDestination() } Here with looks like it is language construction, whereas it is a simple function, receiving lambda as the last parameter. And this leads to such elegant things like Kotlin HTML DSL
A function f :: a -> b can be “disguised” inside double continuations as a function f’ :: ((a -> r1) -> r2) -> ((b -> r1) -> r2). obfuscate :: (a -> b) -> ((a -> r1) -> r2) -> (b -> r1) -> r2 obfuscate f k2 k1 = k2 (k1 . f) … Read more
I personally find methods like cata that take two closures as arguments are often overdoing it. Do you really gain in readability over map + getOrElse? Think of a newcomer to your code: What will they make of opt cata { x => x + 1, 0 } Do you really think this is clearer … Read more
Let’s do a little trace in our heads of how Haskell will evaluate your expression. Substituting equals for equals on each line, the expression pretty quickly evaluates to True: myAny even [1..] foldr step False [1..] step 1 (foldr step False [2..]) even 1 || (foldr step False [2..]) False || (foldr step False [2..]) … Read more
Let’s have a look at def foldLeftViaFoldRight[A,B](l: List[A], z: B)(f: (B,A) => B): B = foldRight(l, (b:B) => b)((a,g) => b => g(f(b,a)))(z) (the other fold is similar). The trick is that during the right fold operation, we don’t build the final value of type B. Instead, we build a function from B to B. … Read more
This will exit after the first element that is out of order. It should thus perform well, but I haven’t tested that. It’s also a lot more elegant in my opinion. 🙂 def sorted(l:List[Int]) = l.view.zip(l.tail).forall(x => x._1 <= x._2)
First of all I’m happy that what I wrote works in clang (I see your update implements 3 out of the 4 steps I mention). I have to give credit to Nick Athanasiou for this technique that discussed this with me way before writing this. The reason I mention this now is because I was … Read more
Try: <details> <summary>Your header here! (Click to expand)</summary> Your content here… > markup like blockquote’s should even work on github! more content here… </details> You can try this sort of thing here: <details> <summary>Your header here! (Click to expand)</summary> Your content here…</br> (markup only where supported)</br> more content here…</br> </details> This works for me with … Read more
The Haskell definition is not uniform. In Racket, the function to both folds have the same order of inputs, and therefore you can just replace foldl by foldr and get the same result. If you do that with the Haskell version you’d get a different result (usually) — and you can see this in the … Read more
The method fold (originally added for parallel computation) is less powerful than foldLeft in terms of types it can be applied to. Its signature is: def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1 This means that the type over which the folding is done has to be a supertype of the collection element … Read more