Randal said...

<<With classic smalltalk 80 and Squeak:

a := (1 to: 10) do: [:n | [n]]. b := a collect: [:each | each value]. b will have something like #(10 10 10 10 ...).

The problem is that the :n in each block ([n]) is shared as one variable. In a true closure, which modern Squeak and Pharo provide, we get the proper #(1 2 3 4 ... 10). That's because each apperance of "n" is "closed" with respect to the newly created block.>>

Thanks for explaining the difference between blocks and closures. I think I new understand that. And, your example raised a new question for me.

What does the inner 'block' in [:n | [n]] actually do?

Out of curiosity I tried changing it to [:n | [n*10]], expecting the numbers to be ten times bigger, but they were stil 1, 2, 3... I also tried removing the whole block, and b still evaluated to the same values.

Cheers Andy