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Single atom array

An array with a single atom is referred to as a singleton. All singletons with the same atom display the same way. However, the fact that they have different ranks affects how verbs act on them. This can be a pitfall for beginners. It is important to remember that if it displays like an atom, but does not behave like one, then check its rank.
   atom =. 5
   list =. 1 $ 5
   atom
5
   list	NB. list looks like atom
5
   atom + 23 23 23
28 28 28
   list + 23 23 23	NB. but does not behave like atom
|length error
|   list    +23 23 23
   # $ atom	NB. rank of atom is 0
0
   # $ list	NB. rank of list is 1
1
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