Over the past few months, I've had to spend a lot of time in Visual Studio (no comments from the peanut gallery, please!). It has a feature that might be useful in DrRacket. When you enter a class or class instance name followed by a dot, you get a popup of valid methods. Yes, DrRacket has the name completion feature. But after you enter one of the VS method names and an open paren, you get a signature (or often, many signatures due to a maddening number of overloads). As you type in arguments, the relevant part of the signature becomes bold-faced.
You really get addicted to this setup -- see the article "Does Visual Studio Rot the Mind?" by Charles Petzold. Currently, DrRacket offers name completion and the ability to lookup names in Help Desk. That works, but it's a bit ungainly. It would be ne plus ultra cool if when you entered (some-fun you got a popup with the arguments to be entered. If `some-fun' is in Help Desk, their arguments could have their names and types. If `some-fun' is defined in the current file or require'd, you'd just have the argument names. Ambitiously, if the argument had a corresponding predicate in a contract, you could show that. -- Paul
