f#

问题 I am fairly new to F#, but have spent the last few weeks reading reference materials. I wish to process a user-supplied input string, identifying and separating the constituent elements. For example, for this input: XYZ Hotel: 6 nights at 220EUR / night plus 17.5% tax the output should resemble something like a list of tuples: [ ("XYZ", Word); ("Hotel:", Word); ("6", Number); ("nights", Word); ("at", Operator); ("220", Number); ("EUR", CurrencyCode); ("/", Operator); ("night", Word); ("plus",

问题 I am trying Infer.Net (An F# Library for Probabilistic Programming) And running the examples in VS11 Beta lead to the error : Could not load file or assembly 'FSharp.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. If I open the dlls used the infer.net samples in Reflector, one, probcomp.dll, says it can not find automatically "FSharp.Core, Version=4.0.0.0"and that I need to select the location by

问题 I'm getting stymied by the way "dot notation" works with objects and records when trying to program in a point-free functional style (which I think is a great, concise way to use a functional language that curries by default). Is there an operator or function I'm missing that lets me do something like: (.) object method instead of object.method ? (From what I was reading about the new ? operator, I think it works like this. Except it requires definition and gets into the whole dynamic binding

问题 Summary of my objective: Figure out how to use continuation-passing style to avoid a stack overflow when using an algorithm I believe cannot be made tail-recursive. Alternatively, find a way to make the function tail-recursive. Details: I am new to F# (and functional programming in general) and I am attempting to implement the minimax algorithm with alpha-beta pruning. This is an algorithm used to determine the best possible move for a two-player game. The pseudocode for the algorithm can be

问题 In goofing around with some F# (via MonoDevelop), I have written a routine which lists files in a directory with one thread: let rec loop (path:string) = Array.append ( path |> Directory.GetFiles ) ( path |> Directory.GetDirectories |> Array.map loop |> Array.concat ) And then an asynchronous version of it: let rec loopPar (path:string) = Array.append ( path |> Directory.GetFiles ) ( let paths = path |> Directory.GetDirectories if paths <> [||] then [| for p in paths -> async { return

问题 I'm trying to build a web app (ASP.NET MVC3) that uses Entity Framework, and I've once again hit a wall. It throws following exception when trying to run a foreach loop over the collection in the view: System.InvalidOperationException: The class 'GvG.Entities.News' has no parameterless constructor. Now is my question, is it possible to somehow define a parameterless constructor on my record type? My record type at the moment looks like: type News = { mutable ID:int; mutable Author:string;

问题 I am currently implementing a Spec framework in F# and I want to hide the Equals, GetHashCode etc. methods on my should type, so that the API is not cluttered with these. I know in C# it is done by making the class implement an interface like this: using System; using System.ComponentModel; public interface IFluentInterface { [EditorBrowsable(EditorBrowsableState.Never)] bool Equals(object other); [EditorBrowsable(EditorBrowsableState.Never)] string ToString(); [EditorBrowsable

问题 I am currently implementing a Spec framework in F# and I want to hide the Equals, GetHashCode etc. methods on my should type, so that the API is not cluttered with these. I know in C# it is done by making the class implement an interface like this: using System; using System.ComponentModel; public interface IFluentInterface { [EditorBrowsable(EditorBrowsableState.Never)] bool Equals(object other); [EditorBrowsable(EditorBrowsableState.Never)] string ToString(); [EditorBrowsable

问题 I am having a hard time trying to unit test F# code with external dependencies. In C# (my background) you would typically have a class with a dependency passed in, which is then re-used. Apologies for my sample code, it's dumb but I'm just trying to illustrate my point. public class Foo { IDependency d; public Foo(IDependency d) { this.d = d; } public int DoStuff(string bar) { return d.DoSomethingToStuff(bar); } public int DoMoreStuff(string bar) { int i = d.DoSomethingToStuff(bar); return d

问题 I'm trying to write a parser for the Mathematica language in F# using FParsec. I have written one for a MiniML that supports the syntax f x y = (f(x))(y) with high precedence for function application. Now I need to use the same syntax to mean f*x*y and, therefore, have the same precedence as multiply. In particular, x y + 2 = x*y + 2 whereas x y ^ 2 = x * y^2 . How can this be accomplished? 回答1: As Stephan pointed out in a comment you can split the operator parser into two separate parsers