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There is a function which looks like f[x_][2]:= . What does 2 in square bracket mean?

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    $\begingroup$ It's a nested function where 2 is one of the arguments. One could also write a function like f[x_][y_] := {x, y}, for instance. $\endgroup$
    – J. M.'s torpor
    Jan 29 at 1:13
  • $\begingroup$ Array[f[x_], 5] $\endgroup$
    – cvgmt
    Jan 29 at 1:31
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    $\begingroup$ You may also find this and this sections of my book useful. There I have briefly discussed such functions. Technically such definitions are called SubValues, and you may search for this term on this site and elsewhere, to find more information on these. $\endgroup$ Jan 29 at 11:24