from collections import Counter a = [1,4,2,3,2,3,4,2] b = Counter(a) #求数组中每个数...
我们用 fold 实现一个搜索子 List 的函数:search :: (Eq a) => [a] -> [a] -> Bool search needle haystack = let nlen = length needle in foldl (\acc x -> if take nlen x == needle then True else acc) False (tails haystack) ...
find取一个 List 和限制条件作参数,并返回首个符合该条件的元素,而这个元素是个Maybe值。在下章,我们将深入地探讨相关的算法和数据结构,但在这里你只需了解Maybe值是Just something或Nothing就够了。与一个 List 可以为空也可以包含多个元素相似,一个Maybe可以为空,也可以是单一元素。同样与 List 类似,一个 Int...
我总是可以把这些场“放在彼此的上面”，这样每个片断在接收到的场中的位置就和它在给定场中的位置一...
Find all unique quadruplets in the array which gives the sum of target. Note: Elements in a quadruplet (a,b,c,d) must be in non-descending order. (ie, a≤ b≤ c≤ d) The solution set must not contain duplicate quadruplets. For example, given array S = {1 0 -1 0 -2 2},...
惰性:Data.ByteString.Lazy,同样具有惰性,但比List稍微勤快一些,不是逐元素的thunk,...-> IO () 实际上,ByteString与String类型在大多数场景可以很容易地互相转换,所以可以先用String实现,在性能不好的场景再改成ByteString P.S.更多ByteString...参考资料 How to catch a divide by zero error in Haskell?
issueInstruction::Instruction->Int->Int->StateCPUBoolissueInstructioninstrtagresult=docpu<-getletfreeRS=V.findIndex(==Nothing)(rscpu)casefreeRSofJustrsIdx->do-- Allocate instruction to the reservation stationletnewRS=V.update(rscpu)[(rsIdx,Just...
如果不记得,回去温习一下这个章节。它们的形式是let bindings in expression,其中bindings是 expression 中的名字、expression则是被运用到这些名字的算式。我们也提到了 list comprehensions 中,in的部份不是必需的。你能够在 do blocks 中使用 let bindings 如同在 list comprehensions 中使用它们一样,像这样:...
What has the [[Scope]] internal property been replaced with in ES6? I can find it in ES5, but no mention of it in ES6. It appears that [[Scope]] has been replaced by [[Environment]] in ES2015. Section... How to reshape a (r, c, 1) matrix to (r, c) ...
Error handling - in Haskell, you will find two major types of error handling employed: "pure" error handling and exceptions Systems programming - attempts a Perl-like "language" that is valid Haskell, implemented in pure Haskell, that makes shell scripting easy ...