Display command

[gwa000]

used APL for a college class years ago and was always intrigued by the language so i have not played around with the language in quite a while.
looked for free APLs until i saw Dyalog APL was free for home users to play around with (not sure when it became free as i do not recall this generosity when i was on my quest for a free version in 2016).

came across this YouTube video and have a few questions related to the presenter's APL output.

https://www.youtube.com/watch?v=PlM9BXfu7UY&t=534s

at 8:50 in the presentation he displays some output and there are boxes around the output.

finally came across how to do this by using the "display" command.

i had to do a )COPY DISPLAY then i could issue DISPLAY 1 2 3.4 'string' and the result was boxed.

i then came across that i could do the same thing with the ]display command (without needing to do the prerequisite COPY).

so a few questions:

1. what is the difference between the two, which is better, is ]display a newer one to use with DISPLAY being left for legacy purposees, etc.?
2. how did the presenter get the boxed output without prefacing the command with "display"?

and as a side question:

3. is there a way to recall previously entered commands? if i type 1 2 + 3 4 and hit enter i get the result. but suppose i meant to multiply. it looks like i can over-type the previous command and hit enter but is there some keystroke to recycle through the previous commands.

thanks!!

gary

[Veli-Matti]

Hi, and welcome!
two quick answers:
typing the user command

      ]box on

should decorate the output with the depth information, and pressing
Ctrl+Shift+Backspace
should bring you back your previous input lines

-Veli-Matti

[gwa000]

exactly what i was looking for.

thanks!!