As the other poster said, the fact that we do not have 1:1 parity has never been a problem.
Some other technologies that are subsets and are wildly successful:
* Android's Java is not a 1:1 mapping to Java either, and that has not prevented it from being successful.
* iPhoneOS is not MacOS 1:1, and yet, it is incredibly successful.
* Chrome the browser, does not have every feature of Firefox, that did not stop it either.
* JBoss is a subset of the full J2EE stack, and for years it has been wildly successful.
* Linux for years was not even POSIX compliant, and yet, many of us jumped on it, and it became wildly successful.
In Mono we implement what makes sense, and what people are actually using in day to day applications, we do this using metrics that we obtain from our Mono Migration Analysis that helps us identify which APIs are used, by how many applications and we have collected this data from some 10,000 applications:
http://go-mono.com/momareports/
Call this the data-driven prioritization of development.
Mono was born as a technology to bring the best that .NET had to offer to Linux, this was initially the c# language and the core libraries. As time went by, Mono evolved in two directions:
(a) Organica growth: as the Mono community grew, we identify missing features, we envisioned better ways of doing something and created tools, APIs, languages and extensions that mattered to us. In this category you can find things like Gtk#, Taglib#, Cairo#, Cecil, Mono.Options, Mono.Security, Mono.Data, Mono.Math, Mono.Management, Mono's C# REPL, Mono's SIMD extensions, Mono's large array support. Mono's dynamic JIT extensions, Mono's static compiler and much more.
For instance, today, more than 350 applications on the AppStore and 10 of the top 100 apps in there are built using Mono.
(b) Better compatibility with .NET: this is a simpler process than coming up with our own APIs. The .NET APIs are documented, there are thousands of applications to test the implementation against, the community is fed directly from the largest middleware stack in the world, so it made sense for us to implement these pieces.
Is it correct that we do not have a full implementation of .NET, there are a few reasons for this, now with numerals:
(i) Some APIs are Windows specific, and makes no sense to bring to Linux, in particular things like System.Management which is a thin wrapper around WMI. Our advise: replace that code with Linux and MacOS specific code and use one or the other at runtime.
(ii) Some APIs are too larger for us to take with our current community. This includes things like WPF and Workflow. If someone steps up, we will embrace them, but until that happens, we are focused on improving the other areas that have more users and that we have more requests to implement. Additionally, the WPF "lite" is a killer stack (also known as Silverlight).
(iii) Focus, we do not want to spread ourselves too thin.
As for .NET 4.0: we are not too far from having the core be 4.0 compliant, it is a nice upgrade to the solid 3.5 release. For instance, our C# compiler is already a full C# 4.0 compiler, and we already provide features that Microsoft wont offer until 5.0 (embeddable, reusable compiler, see C# REPL).
Moonlight is behind Silverlight, but I am not driven by despair, I am driven by the world of possibility. If I were driven by despair, I would not have written a single line of code.
If Silverlight never succeeds, then who cares how behind Moonlight is. But if Silverlight succeeds, and Linux users want to access that content, but the feature is either broken, not implemented or missing in Moonlight, those users will be in a position to contribute the code, and everyone wins.
