.net – Why are many ports of languages to .net prefixed with ‘Iron’

In general, methods that end in ! indicate that the method will modify the object it's called on. Ruby calls these as "dangerous methods" because they change state that someone else might have a reference to. Here's a simple example for strings:

foo = "A STRING"  # a string called foo
foo.downcase!     # modifies foo itself
puts foo          # prints modified foo

This will output:

a string

In the standard libraries, there are a lot of places you'll see pairs of similarly named methods, one with the ! and one without. The ones without are called "safe methods", and they return a copy of the original with changes applied to the copy, with the callee unchanged. Here's the same example without the !:

foo = "A STRING"    # a string called foo
bar = foo.downcase  # doesn't modify foo; returns a modified string
puts foo            # prints unchanged foo
puts bar            # prints newly created bar

This outputs:

A STRING
a string

Keep in mind this is just a convention, but a lot of Ruby classes follow it. It also helps you keep track of what's getting modified in your code.

In .NET 4.0 the DLR consists of what you can consider "DLR v1.0". This includes the call site caching mechanism, the cross-language interop featuers, and the improvements to the existing LINQ expression trees. These are all features which are very useful for implementing a langauge but not hosting a language.

And that's the missing piece in DLR 1.0 - a shared hosting story for all languages. But we do have a start on that in the form of the hosting APIs we ship on CodePlex w/ DLR and IronPython projects and also w/ IronRuby over on github. Unfortunately we didn't think that we could drive these APIs to being ship quality in the .NET 4.0 timeframe so we didn't include them. In particular we want to get more feedback from other languages like Powershell and even VB and C# to make sure we have the right APIs.

Therefore every language more or less has it's own hosting story except for IronPython and IronRuby right now. But we'd love to see all of this get unified in the future so your users can choose what language to use. But right now there's just not something in the box for Powershell to target.