Prototype erasing variable

[Mr. Sunday]

GNU APL replaces a variable's contents when taking the prototype with 0⍴⊂.  Note also that a second variable assigned to the original variable is also affected.

                    ______ _   __ __  __    ___     ____   __

                   / ____// | / // / / /   /   |   / __ \ / /

                  / / __ /  |/ // / / /   / /| |  / /_/ // /

                 / /_/ // /|  // /_/ /   / ___ | / ____// /___

                 \____//_/ |_/ \____/   /_/  |_|/_/    /_____/

                  Welcome to GNU APL version 1.8 / SVN: 1646

                Copyright (C) 2008-2021  Dr. Jürgen Sauermann

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                This program comes with ABSOLUTELY NO WARRANTY;

            for details run: /usr/local/bin/apl --gpl.

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         according to the GNU Public License (GPL) version 3 or later.

      data←1 2 3 ('ABCDE' (10 20 30 40 50 60 70))

      save←data

      ⊃data save

1 2 3   ABCDE  10 20 30 40 50 60 70

1 2 3   ABCDE  10 20 30 40 50 60 70

      ⍴⊂data

      ⊃data save

1 2 3   ABCDE  10 20 30 40 50 60 70

1 2 3   ABCDE  10 20 30 40 50 60 70

      0⍴⊂data

      ⊃data save

0 0 0          0 0 0 0 0 0 0

0 0 0          0 0 0 0 0 0 0

Thank you for help.

-- To believe is to die.