Lexical Scope and Block Structure

DrScheme's Check Syntax button analyzes the program in the definitions window and highlights it with lexical binding information. After clicking Check Syntax, when you move the mouse pointer over a binding instance of a variable, DrScheme draws arrows to all of the bound uses of the variable. Similarly, when you move the mouse pointer over a bound variable, DrScheme draws an arrow to the binding instance.

When the mouse pointer is over a variable, the right mouse button pops up a special menu for pinning arrows, or for renaming a variable (including its binding instance and all uses).