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Comment by benhurmarcel | Hacker News Reader

What happens if you reassign a variable below? Like:

  a = 1
  println(a)
  a = 2

Does it show 1 or 2?

Edit: tested it, it throws an error "Multiple definitions for a: Combine all definitions into a single reactive cell using a `begin ... end` block."

Not sure I like that way of working.

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In a more complex example where you actually take a variable, do some operations to it, then reassign it, Pluto.jl encourages you to separate that into multiple cells. The reason is each cell marks a distinct node in the dependency graph. If you prefer to use cells, then the notebook can be smarter about what lines actually need to get re-run and what don't.

A downside to using multiple cells is vertical spacing/visual noise. This is something that the package authors are currently thinking about addressing.

Think of it as working with immutable data, because that's essentially what it is. Which has all the pros and cons of that approach (in my opinion a lot more pros, but YMMV).

Yes, that's the best explanation in the end I think. Maybe I'm too used to reuse variables and that's a bad habit I should work on. For example most of my counters are called i.

You just update the `a=1` cell, changing it to `a=2`. That's the whole point.

Every other cell that depends upon `a` will then automatically update.

Exactly. It requires a change in mindset wrt Jupyter, but it is totally worth it!

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