heterogeneous

问题 When using the Scala standard lib, I can do somthing like this: scala> val scalaList = List(1,2,3) scalaList: List[Int] = List(1, 2, 3) scala> scalaList.foldLeft(0)((acc,n)=>acc+n) res0: Int = 6 Making one Int out of many Ints. And I can do something like this: scala> scalaList.foldLeft("")((acc,n)=>acc+n.toString) res1: String = 123 Making one String out of many Ints. So, foldLeft could be either homogeneous or heterogeneous, whichever we want, it's in one API. While in Spark, if I want one

问题 Let a module to abstract Area operations (bad definition) class Area someShapeType where area :: someShapeType -> Float -- module utilities sumAreas :: Area someShapeType => [someShapeType] sumAreas = sum . map area Let a posteriori explicit shape type modules (good or acceptable definition) data Point = Point Float Float data Circle = Circle Point Float instance Surface Circle where surface (Circle _ r) = 2 * pi * r data Rectangle = Rectangle Point Point instance Surface Rectangle where

问题 I'm trying to encode a list of items which have types restricted to be instances of some type class: {-# LANGUAGE RankNTypes, TypeSynonymInstances, LiberalTypeSynonyms #-} module Test where class Someable a where some :: a -> String data Some = Some String type SomeGroup = forall a. Someable a => [a] instance Someable Some where some (Some v) = v instance Someable SomeGroup where some (x:xs) = (some x) ++ ", " ++ (some xs) main = do putStrLn $ show.some [Some "A", [Some "B", Some "C"]] But

问题 With ANTLR2, you could define something like this in grammar definition file: options { language = "CSharp"; namespace = "Extended.Tokens"; } tokens { TOKEN<AST=Extended.Tokens.TokenNode>; } And then, you could create a class: public class TokenNode: antlr.BaseAST { ... } Any ideea if something like this can be used (delegate class creation to AST factory instead of me doing the tree replication manually)? It's not working just by simple grammar definition copy from old to new format, and I

问题 I am trying to create heterogeneous arrays that contain variables of different types, for example, [ 1.0, 7, "hi" ] . I tried to include class(*) or type(*) in the array constructor (please see the end of the following code), but gfortran5.2 simply regards it as syntax error. Is there any way to make such an array with array constructor, or is it necessary to use a different approach (e.g., define a type that contains each element separately)? More details: The following code is an example

问题 I'm using nvprof to get the number of global memory accesses for the following CUDA code. The number of loads in the kernel is 36 (accessing d_In array) and the number of stores in the kernel is 36+36 (for accessing d_Out array and d_rows array). So, the total number of global memory loads is 36 and the number of global memory stores is 72. However, when I profile the code with nvprof CUDA profiler, it reports the following: (Basically I want to compute the Compute to Global Memory Access

问题 I have a variadic class template that is used to create a top-level class for a variable number of classes. Each class that is to go in the top-level class is derived from a base class, as there is common functionality for them. I don't know the best way to store the derived classes in the parent class, but still be able to access the full functionality of the derived class. If I store the variadic args in a vector, they'll all be stored as a base class and I can't access the derived

问题 I have checked over the whole web and couldn't find a solution that seems to work for me.. I have recreated my stored procedure, making sure to have these lines as first lines: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_WARNINGS ON GO CREATE PROCEDURE test_insert AS .... BEGIN ... END I only get this error when i call my stored procedure from php. it works fine in sql server.. i really don't know what else i can do..please help me ;_; 回答1: Added this BEFORE your statement

问题 It seems to me that adding the property svn:ignore on files like .classpath would be a good idea. I use both Windows (work, ugh) and Linux development environments and every time I sync with the repository it overwrites my .classpath from whichever machine I'm working on. I tried right-clicking the .classpath file in the Team Sync perspective, but the svn:ignore option is greyed out. Any ideas how I might: 1. get this item out of source control, 2. add it to an ignore list? Any other files a

问题 I need an heterogeneous, typesafe container to store unrelated type A, B, C. Here is a kind of type-level specification : trait Container { putA(a: A) putB(b: B) putC(c: C) put(o: Any) = { o match { case a: A => putA(a) case b: B => putB(b) case c: C => putC(c) } getAllAs : Seq[A] getAllBs : Seq[B] getAllCs : Seq[C] } Which type is best suites to backed this container ? Is it worth creating a Containerable[T] typeclass for types A, B, C ? thks. 回答1: As other have suggested, you can leverage