You asked for all elements of a list of lists. That is, for [[1,2,3],[4]] this would be the list [1,2,3,4]. However, for [[[1],[3]]] this would be the list [[1],[3]] since [1] and [3] are elements. For this reason, flatten/2 is incorrect it gives you [1,3] as an answer. Also, for 1 it gives [1]… Here … Read more
Basically, because [10..1] is translated to enumFromTo 10 1 which itself has the semantics to create a list by taking all elements less-than 1 which result from counting upward (with step-size +1) from (including) 10. Whereas [10, 9..1] is translated to enumFromToThen 10 9 1 which explicitly states the counting step-size as 9-10, i.e. -1 … Read more
Here goes an implementation: subset([], []). subset([E|Tail], [E|NTail]):- subset(Tail, NTail). subset([_|Tail], NTail):- subset(Tail, NTail). It will generate all the subsets, though not in the order shown on your example. As per commenter request here goes an explanation: The first clause is the base case. It states that the empty list is a subset of the … Read more
You are getting multiple solutions due to Prolog’s backtracking. Technically, each solution provided is correct, which is why it is being generated. If you want just one solution to be generated, you are going to have to stop backtracking at some point. This is what the Prolog cut is used for. You might find that … Read more
You could use something like a set from Programming in Lua: function Set (list) local set = {} for _, l in ipairs(list) do set[l] = true end return set end Then you could put your list in the Set and test for membership: local items = Set { “apple”, “orange”, “pear”, “banana” } if … Read more
Use toSet and then toList var ids = [1, 4, 4, 4, 5, 6, 6]; var distinctIds = ids.toSet().toList(); Result: [1, 4, 5, 6] Or with spread operators: var distinctIds = […{…ids}];
I wouldn’t use checkboxes, i’d use the code you already have DEMO http://jsfiddle.net/6W7XD/1/ CSS body { display: block; } .span3:focus ~ .alert { display: none; } .span2:focus ~ .alert { display: block; } .alert{display:none;} HTML <span class=”span3″>Hide Me</span> <span class=”span2″>Show Me</span> <p class=”alert” >Some alarming information here</p> This way the text is only hidden on … Read more
Your first definition, kart xs ys = [(x,y) | x <- xs, y <- ys], is equivalent to kart xs ys = xs >>= (\x -> ys >>= (\y -> [(x,y)])) where (x:xs) >>= g = g x ++ (xs >>= g) (x:xs) ++ ys = x : (xs ++ ys) are sequential operations. Redefine … Read more
My KISS approach to skip some folders is chaining Get-ChildItem calls. This excludes root level folders but not deeper level folders if that is what you want. Get-ChildItem -Exclude folder1,folder2 | Get-ChildItem -Recurse | … Start excluding folders you don’t want Then do the recursive search with non desired folders excluded. What I like from … Read more
list.groupBy(_.property).map(_._2.head) Explanation: The groupBy method accepts a function that converts an element to a key for grouping. _.property is just shorthand for elem: Object => elem.property (the compiler generates a unique name, something like x$1). So now we have a map Map[Property, List[Object]]. A Map[K,V] extends Traversable[(K,V)]. So it can be traversed like a list, … Read more