main =doletx = [1..10] putStrLn"Our list is:"print(x) putStrLn"The first element of the list is:"print(headx) 它将产生以下输出 : Our list is: [1,2,3,4,5,6,7,8,9,10]The first element of the list is:1 尾部函数 Tail是补充head功能的功能.它需要一个列表作为输入,并产生没有...
-- file Spec.hsimportTest.HspecimportTest.QuickCheckimportControl.Exception (evaluate)main::IO()main= hspec $dodescribe"Prelude.head"$doit"returns the first element of a list"$dohead [23..] `shouldBe` (23::Int) it"returns the first element of an *arbitrary* list"$ property $ \x xs ...
https://hackage.haskell.org/package/base-4.17.0.0/docs/Data-List.html#v:tail ...
length head: returns the first element of a (non-empty) list tail: returnsall but the firstelement use function on List:map,filter,foldr foldr&&foldl folding is like replacing (:) with a particular function and ([]) with an initial element foldrassumes the function is right-associative: fo...
first; MyList<T> rest = ((ListNode)list).rest; return new ListNode(first, appendRight(rest, element)); } throw new RuntimeException(); } 我们对列表的右边加了一个新元素,但是旧的列表仍然没有改变,我们只是获得了一个被“改变”了的新列表,这就是用数据变换代替修改的思想。 惰性求值 数据的完全...
Conduit.ListasCLimportText.HTML.DOM(sinkDoc)importText.XML.Cursor(attributeIs,content,element,from...
EAN是标准条形码，目前商店里大多数商品上都打有此码，是世界通用的条形码。EAN13码是由前缀码、厂商...
Haskell中的Pascal三角这个定义生成了一个包含所有斐波那契数的无限列表，并且非常有效（从CPU的Angular 来看...
Click in a specific element of list of web elements in Java selenium I am automating a web page using cucumber and selenium in java, and I have this xpath and inside the ul[1] I have a bunch of li, in this case I have this portion of html: And I want to click in a spec.....
What do you think is the type of the head function? Because head takes a list of any type and returns the first element, so what could it be? Let's check! ghci> :t head head :: [a] -> a Hmmm! What is this a? Is it a type? Remember that we previously stated that types ...