For #3, you can avoid using an object argument and casting by typing the
argument as the the non-generic IList and IDictionary.
I think you're correct with #2 as F# doesn't support Nullable<T> syntactically,
but it doesn't mean F# can't consume code using Nullable.
~Jimmy
On Apr 4, 2011, at 11:24 AM, Doug Blank <doug.bl...@gmail.com> wrote:
> I'm working on writing C# libraries which can be imported by a variety
> of .NET languages, DLR and otherwise, which appear native to the
> language importing them.
>
> For example, writing a C# function that can be used naturally in
> IronPython as if it were written in Python, IronRuby as if it were
> written in Ruby, and F# as if it were written in F#, etc.
>
> I've encountered some gotchas that I thought I'd share, and looking
> for any other points of advice in writing cross-language libraries.
>
> 1. IronRuby strings aren't really strings, so you need to pass them in
> as an object, and call .ToString().
>
> public static string expects_string(object val) {
> return val.ToString();
> }
>
> 2. F# 2.0 doesn't seem to automatically convert a type to the
> associated nullable type, so avoid nullable types as parameters.
>
> // AVOID:
> public static double? expects_nullable(double? var1=null) {
> return var1;
> }
>
> // BETTER:
> public static double? expects_nullable() {
> return null;
> }
> public static double expects_nullable(double var1) {
> return var1;
> }
>
> 3. IronPython and IronRuby lists and dictionaries implement IList and
> IDictionary, so no problem with those.
>
> public static IDictionary<object,object> make_dict(object val) {
> if (val as IDictionary<object,object> != null) {
> return ((IDictionary<object,object>)val);
> } else
> throw new System.ArgumentException("object is not a dictionary");
> }
>
> public static IList<object> make_list(object val) {
> if (val as IList<object> != null) {
> return ((IList<object>)val);
> } else
> throw new System.ArgumentException("object is not a list");
> }
>
> Any other suggestions?
>
> -Doug
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