transpose templates
  a is $;
  $a(1; .. as j; -> $a(..; $j)) !
end transpose

printMatrix templates
  formatN templates
    @ set [];
    $ -> !#
    '$@ -> $::length~..2 -> ' ';$@(..:-1)...;' !
    when <|1..> do ..|@ set $ mod 10; $ ~/ 10 -> !#
  end formatN
  $... -> '|$($::first) -> formatN;$(~..)... -> ', $ -> formatN;';|
' !
end printMatrix

m is [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]];
'before:
' !
$m -> printMatrix !

mT is $m -> transpose;
'
transposed:
' !
$mT -> printMatrix !