C# REPL - execute one-off C# code on the fly from within VS
I'd like to see a full read/eval/print loop for C# built into Visual Studio - much like F# Interactive, or Ruby's "irb".
When debugging, this would let you interact with the current state of the debugged application - like the Immediate Window does now, but more powerful (e.g. with support for lambdas).
When in design/editing mode, this would work a lot like LinqPad, but integrated into the IDE. It would let you evaluate expressions and execute multi-statement code blocks. This would let developers interactively experiment with their application classes ,.NET framework classes, and third-party APIs while writing code in Visual Studio.
A read-eval-print loop (REPL), also known as an interactive toplevel, is a simple, interactive computer programming environment. The term is most usually used to refer to a Lisp interactive environment, but can be applied to command line shells and similar environments for Smalltalk, Standard ML, Perl, Prolog, Scala, Python, Ruby, Haskell, APL, BASIC, J, Tcl, and other languages as well.
In a REPL, the user may enter expressions, which are then evaluated, and the results displayed. (c) Wiki
Karen Ng commented
We've also just released a preview of the C# Interactive feature for design-time in the Roslyn CTP release. You can download it today (it's a tiny install on top of Visual Studio 2010 SP1) and try it out!
Wow, you guys are in for a treat. If you haven't seen it already you simply must watch this talk on the Future directions for C# and Visual Basic given by Anders Hejlsberg at the Microsoft BUILD conference. All of it is exciting but I suggest you pay special attention to the part about 40 minutes in!:
Anthony D. Green | Program Manager | Visual Basic & C# Languages Team