CODEWITHSUNDEEP
linqf#linq-expressionsquotations
bp123
bp123

Reputation: 195

Converting C# Expression Parsing to F#

As a newbie to F#, I routinely try to convert bits of C# over as a learning exercise. In this case, I am trying to convert the following C# expression parsing code. It's simple, the idea is to pass a lambda into this function to get the string representation of a property name, rather than using standard reflection techniques. I have omitted the other GetMemberName function as I think I can figure it out once I get some guidance on what approach to take.

public static string GetMemberName<T>(Expression<Func<T, object>> expression)
{
    if (expression == null)
    {
        throw new ArgumentException("The expression cannot be null.");
    }
    return GetMemberName(expression.Body);
}

I know that F# has quotations. I also know I could use Linq Expressions in F#. I would like to try it the F# way first using quotations, but I am stumbling. Could someone give me a kickstart?

Upvotes: 1

Views: 182

Answers (1)

Daniel
Daniel

Reputation: 47904

I'm not sure if an exact translation of this is possible using quotations because quotations have a different shape than C# expressions. However, here's something along the same lines:

open Microsoft.FSharp.Quotations.Patterns

let GetMemberName = function
    | Call (_,methodInfo,_) -> methodInfo.Name
    | PropertyGet (_,propertyInfo,_) -> propertyInfo.Name
    | _ -> failwith "Not a member expression"

GetMemberName <@ [].IsEmpty @>
// val it : string = "IsEmpty"

Upvotes: 3

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