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## The Interactions Window

The interactions window lets you type an expression after the `>` prompt for immediate evaluation. You cannot modify any text before the last `>` prompt. To enter an expression, the flashing caret must appear after the last prompt, and also after the space following the prompt.

When you type a complete expression and hit Enter or Return, DrScheme evaluates the expression and prints the result. After printing the result, DrScheme creates a new prompt for another expression. Some expressions return a special ``void'' value; DrScheme never prints void, but instead produces a new prompt immediately.

If the expression following the current prompt is incomplete, then DrScheme will not try to evaluate it. In that case, hitting Enter or Return produces a new, auto-indented line.

To copy the previous expression to the current prompt, type ESC-p (i.e., type Escape and then type p). Type ESC-p multiple times to cycle back through old expressions. Type ESC-n to cycle forward through old expressions. Also, if you move the flashing caret after an old expression and hit Enter or Return, DrScheme copies the expression to the current prompt.

Clicking the Execute button evaluates the program in the definitions window and makes the program's definitions available in the interactions window. Clicking Execute also resets the interactions window, erasing all old interactions and removing old definitions from the interaction environment. Although Execute erases old `>` prompts, ESC-p and ESC-n can still retrieve old expressions.