While you build

Learn within seconds whether the last change broke something.

  1. Stop 1, next

    Prove it works verification

    Think of it when anyone, you or an agent, says "done".

    StartAbout 3 minutes. The word for it comes at the end.

  2. Stop 2, next

    One red command feedback loop

    Think of it when something is broken, or you are about to change code you cannot check by eye.

    StartAbout 3 minutes. The word for it comes at the end.

  3. Stop 3, next

    Test what, not how behavior tests

    Think of it when you write a test, or a small change inside the code breaks many tests.

    StartAbout 3 minutes. The word for it comes at the end.

  4. Stop 4, next

    Impossible to write types

    Think of it when a mistake could be caught by the shape of the data, such as two ids that are easy to swap or a case nobody handled.

    StartAbout 3 minutes. The word for it comes at the end.