C# switch in lambda expression

Question

Is it possible to have a switch in a lambda expression? If not, why? Resharper displays it as an error.

Answer 1

In a pure Expression (in .NET 3.5), the closest you can get is a compound conditional:

    Expression> func = x =>
        x == 1 ? "abc" : (
        x == 2 ? "def" : (
        x == 3 ? "ghi" :
                 "jkl")); /// yes, this is ugly as sin...

Not fun, especially when it gets complex. If you mean a lamda expression with a statement body (only for use with LINQ-to-Objects), then anything is legal inside the braces:

    Func func = x => {
        switch (x){
            case 1:  return "abc";
            case 2:  return "def";
            case 3:  return "ghi";
            default: return "jkl";
        }
    };

Of course, you might be able to outsource the work; for example, LINQ-to-SQL allows you to map a scalar UDF (at the database) to a method on the data-context (that isn't actually used) - for example:

var qry = from cust in ctx.Customers
          select new {cust.Name, CustomerType = ctx.MapType(cust.TypeFlag) };

where MapType is a UDF that does the work at the db server.