head takes a list and returns its head. The head of a list is basically its first element.(提取第一个元素) ghci> head [5,4,3,2,1] 5 tail takes a list and returns its tail. In other words, it chops off a list's head.(
是世界通用的条形码。EAN13码是由前缀码、厂商识别码、商品项目代码和校验码组成，总共13位数字。他的编...
Haskell thinks of Strings as a list of characters, which is what[Char]means. We'll get to that later. True and False correspond to theBooltype, just like we'd expect. The'a'character is a singleChar. Our numbers are a little more complicated. Ignore theNumandFractionalwords for now. ...
K = random:uniform(N) - 1, Ek = array:get(K, Array), En = array:get(N, Array), shuffle(array:set(K, En, array:set(N, Ek, Array)), N-1). jpalecek 的area of a polygon例子: def area(figure : List[Point]) : Float = { if(figure.empty) return 0 val last = figure(0)...
在线运⾏ main=do let x=[1..10] putStrLn Our list is: print (x) putStrLn The last element of our list is: print (last x) 它将产⽣以下输出- Our list is: [1,2,3,4,5,6,7,8,9,10] The last element of our list is: 10 初始函数 吾⽣也有涯,⽽知⽆涯 - ⽆涯教程...
Current element: 1 Enter Return, q or the replacement value:Current element: 2 Enter Return, q or the replacement value:Current element: 6 Enter Return, q or the replacement value: 42 Current element: 24 Enter Return, q or the replacement value: q Done: fromList [(1,1),(2,2),(3,...
Get submatch indices-- match of __entire__ regex is first element, not first capture -- can also return Data.Array instead of List getAllSubmatches (a =~ b) :: [(Int, Int)] -- (index, length) λ> getAllSubmatches ("div[attr=1234]" =~ "div\\[([a-z]+)=([^]]+)\\]"...
-- Having code split up into several modules has quite a lot of advantages. If a module is generic enough, the functions it exports can be used in a multitude of different programs. -- which is by default import Data.List numUniques :: (Eq a)=> [a] -> Int ...
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 ...
Here is a diagram of how Gaussian Elimination works. On each iteration, the element circled in green is considered thepivotelement, while the elements enclosed in the red square are the ones we intend to remove (zero) in each iteration. ...