swift 1期day21 25函数式编程

letletarr=[1,2,letresult=arr.lazy.map{(i:Int)->Intinprint("mapping\(i)")returni*2} print("mapped",result[0])print("mapped",result[1])print("mapped",result[2])print("endmapping1mappedmappingmappedmappingmappedvarnum1:Int?=//varnum2=num1.map{$0*2varfmt=DateFormatter()fmt.dateFormat="yyyy-MM-dd"varstr:String?="2011-09-10"//varnum3:Int?=//varnum4=num3.map{$0*2vardate1=str!=nil?fmt.date(from:str!)://vardate2=varnum1:varnum1:Int?=//varnum2=num1.map{Optional.some($0*2)//varnum3=num1.flatMap{Optional.some($0*}varscore:Int?=//varstr1=score!=nil?"socreis\(score!)":"No//varstr2=score.map{"scoreis\($0)"}??"Novarnum1:Int?=varnum2=(num1!=nil)?(num1!+10):nilvarnum3=num1.map{$0+10}structstructPersonvarname:Stringvarage:Intinit?(_json:[String:Any])guardletname=json["name"]as?String,letage=json["age"]as?Intelse{return}=nameself.age=age}}varjson:Dictionary?=["name":"Jack","age"://varp1=json!=nil?Person(json!)://varp2=函数式编程（FuntionalpnpHigher-OrderFunction、FunctionpFunctor、ApplicativeFunctor、nphttp://adit.io/posts/2013-04-17-functors,applicatives,andmonadsinFP假设要实现以下功能：[(numvarnum=1+*5-%/add(_v1:_v2:->Int+}sub(_v1:_v2:->Int-}multiple(_Int,_Int)->{*v2divide(_v1:Int,_v2:Int)->Intv1v2mod(_v1:Int,_v2:Int)->Int{%}dividedivide(mod(sub(multiple(add(num,3),5),1),10),FPadd(_v:->(Int)->Int{{+v}sub(_v:multiple(_->(Int)->Int{{Int)->(Int)->Int-{v}$0*}divide(_v:Int)->(Int)->Int{mod(_v:Int)->(Int)->Int{{$0/v%v}}infixoperator>>>:func>>><A,B,_f1:@escaping(A)->f2:@escaping(B)->C)->C{{f2(f1($0))}varvarfn=add(3)>>>multiple(5)>>>sub(1)>>>mod(10)>>>divide(2)np接受一个或多个函数作为输入（map、filter、reduce等pnFPfuncfuncadd(_v:Int)->(Int)->Int{{$0+v}npfuncadd(_v1:Int,_v2:Int)->Int{v1+v2}add(10,20)funcfuncadd(_v:Int)->(Int)->Int{{$0+v}}nArray、Optional的mapadd1(_v1:Int,_v2:Int)->Int{v1v2add2(_v1:Int,_v2:Int,_v3:Int)-Int++}funccurrying<A,B,C>(_fn:@escaping(A,->(B)->(A)->C{bin{ainfn(a,b)}}funccurrying<A,B,C,D>(_fn:@escapingC)->->(C)->(B)->(A)->D{cin{bin{ainfn(a,b,c)}}}letcurriedAdd1=letcurriedAdd2=currying(add2)add(_v1:_v2:->Int{+}sub(_v1:_v2:->Int{-}multiple(_Int,_Int)->{*v2divide(_v1:Int,_v2:Int)->Intv1v2mod(_v1:Int,_v2:Int)->Int{%}prefixfuncprefixfunc~<A,B,C>(_fn:@escaping(A,B)->->(B)->(A)->C{{bin{ainfn(a,b)}}infixoperator>>>:func>>><A,B,C>(_f1:@escaping(A)->_f2:@escaping(B)->C)->(A)->C{{f2(f1($0))}varnum=varfn=(~add)(3)>>>(~multiple)(5)>>>(~sub)(1)>>>(~mod)(10)>>>n像Array、Optional这样支持map运算的类型，称为函子////publicfuncmap<T>(_transform:(Element)->T)->//publicfuncmap<U>(_transform:(Wrapped)->U)-> n对任意一个函子Ffuncfuncpure<A>(_value:A)->func<*><A,B>(fn:F<(A)->B>,value:F<A>)->nOptionalfuncpurefuncpure<A>(_value:A)->A?{value}infixoperator<*>:AdditionPrecedencefunc<*><A,B>(fn:((A)->B)?,value:A?)->B?{guardletf=fn,letv=valueelse{returnnil}returnf(v)}varvalue:Int?=varfn:((Int)->Int)?={$0*//print(fn<*>valueasnArrayfuncfuncpure<A>(_value:A)->[A]{[value]func<*><A,B>(fn:[(A)->B],value:[A])->[B]vararr:[B]=iffn.count==value.countforiin{}}return}//[10]varar