我試圖使該組合本身功能的擴展功能 -缺少的參數類型以下劃線
def genericComposition[T](f: T => T, g: T => T) = {
def call(x: T) = g(f(x))
call _
}
def testComposition[T](g: T=>T, n: Int) = {
val call = genericComposition[T](g,g)
def helper(res: T, m: Int) : T = {
if(m == 0) res
else helper(call(res), dec(m))
}
helper(_,n)
}
這應該叫F的組成與F(F(F(X))n次,非通用版本,所有T的是int或double等工作正常,但是當我試圖讓仿製藥我用下劃線來傳遞x作爲參數傳遞給輔助函數,但有錯誤:
Error:(26, 11) missing parameter type for expanded function ((x$1: ) => helper(x$1, n)) helper(_,n)
^