Introduction to the REPL and Interrupting a Running Program

The Sheerpower REPL — Read–Eval–Print Loop

You can open the Sheerpower console in several ways: by starting SPDEV, using Visual Studio Code, or typing sp4gl at the Windows command prompt. This launches the Sheerpower console, which functions like a REPL (Read–Eval–Print Loop) found in many other programming languages. A REPL is an interactive programming environment where you enter code, have it evaluated immediately, and see the results printed right away. In Sheerpower, you can also enter multiple statements on a single line by separating them with a backslash (\).

Interrupting a Running Program

When a Sheerpower program is running in its console window, you might encounter a situation where the program is taking too long to complete, or you suspect it's stuck in an infinite loop. For these moments, Sheerpower provides a powerful built-in debugging feature.

By clicking anywhere in the console window to give it focus and then pressing ALT+B, you can immediately halt the program's execution.

This action does more than just stop the program—it drops you directly into the Sheerpower REPL (Read–Eval–Print Loop) at the exact point where the program was interrupted. The console will display the source file and line number where the halt occurred, giving you immediate context.

From within this interactive state, you can:

• Inspect Variables: Type print variable_name to see the current value of any variable.
• Evaluate Expressions: Test conditions or perform calculations with live data.
• Resume Execution: Type go to allow the program to proceed from where it left off.
• Stop Execution: Type stop to terminate the program completely or simply close the window.