Midnight Pub

Programming a PB&J

~mnbryant

The post that inspired this

The above post reminded me of an analogy I once heard to try to explain to non-programmers what programming is actually like.

Suppose you are teaching someone how to make a peanut butter and jelly sandwich. For most people, the instructions would look something like:

This would not work for a computer, though. If we look closer at just that first step, we would need to tell the computer to get the slices of bread from the pantry.

Error: could not find slices of bread. Found: loaf of bread, jar of peanut butter, [...]

There was a logical skip in our instructions: to get the loaf out and take slices from it. The computer doesn't know how to infer that step (ignoring machine learning/artificial intelligence), so it fails.

If we extrapolate this further and remove any assumptions about how to make a sandwich and what to do if the current state is not as we expect (e.g. a door is closed but instructions assume it is open), we get the following list of computer-friendly instructions:


errant

My English teacher once taught this lesson, although I can't remember why (grammar rules?). I felt pretty clever with my list of ~20 steps until she pointed out, rather dramatically, that I hadn't described _how_ to get bread out of the bag by wrenching it apart and scattering slices across the front row of students.

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bitdweller

To illustrate how "difficult" it is to program (finnicky may be a better word, if my understanding of English is correct), I will add some steps:

This is just for fun, not to actually "correct" you :)

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