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It's funny, I know about stacks, call stacks, and call stack frames. And yet the analogy to a literal stack of papers with information written on each one still

It's funny, I know about stacks, call stacks, and call stack frames. And yet the analogy to a literal stack of papers with information written on each one still gave me something new to chew on. (For some reason, I never actually thought to visualize like... a physical stack of data before.)

DonHopkins 8y ago
I made a visual programming and debugging environment for PostScript, a stack based language, that let you perform "direct stack manipulation" by dragging object up and down and on and off of a "spike" stack that impaled the little tabs sticking out of objects. https://medium.com/@donhopkins/the-shape-of-psiber-space-october-1989-19e2dfa4d91e https://medium.com/@donhopkins/the-shape-of-psiber-space-oct...
- rhencke 8y ago
  As someone who spent a few years having to debug PostScript with pstack and GhostScript running in a fixed-size command-prompt window in the 2010-ish timeframe... this looks futuristic even today. Was the idea with the direct stack manipulation dragging you describe to provide visual analogues to PostScript commands like roll/pop/etc?
  - DonHopkins 8y ago
    That's right -- you could rearrange their vertical order to manipulate their place on the stack, or you could lift them off of the stack and let them float by themselves, just to have a visual reference you can click on, drag and drop into other objects, etc. It was very dangerous since you were editing the live data structures of the window system! The most complicated program I used it to debug was itself. It was integrated with NeWS's multithreaded debugger, so when some process hit a bug or a breakpoint, you could "enter" the process and see what was on its stack, peek and poke at the objects, rearrange the stack and edit the objects, then send it on its way. Since PostScript is homoiconic like Lisp, code and objects are made of arrays and dictionaries, which you could visually browse, edit, and execute. Very much inspired by Smalltalk, but with a twist of Lisp and FORTH!

DonHopkins 8y ago

I made a visual programming and debugging environment for PostScript, a stack based language, that let you perform "direct stack manipulation" by dragging object up and down and on and off of a "spike" stack that impaled the little tabs sticking out of objects. https://medium.com/@donhopkins/the-shape-of-psiber-space-october-1989-19e2dfa4d91e https://medium.com/@donhopkins/the-shape-of-psiber-space-oct...

rhencke 8y ago
As someone who spent a few years having to debug PostScript with pstack and GhostScript running in a fixed-size command-prompt window in the 2010-ish timeframe... this looks futuristic even today. Was the idea with the direct stack manipulation dragging you describe to provide visual analogues to PostScript commands like roll/pop/etc?
- DonHopkins 8y ago
  That's right -- you could rearrange their vertical order to manipulate their place on the stack, or you could lift them off of the stack and let them float by themselves, just to have a visual reference you can click on, drag and drop into other objects, etc. It was very dangerous since you were editing the live data structures of the window system! The most complicated program I used it to debug was itself. It was integrated with NeWS's multithreaded debugger, so when some process hit a bug or a breakpoint, you could "enter" the process and see what was on its stack, peek and poke at the objects, rearrange the stack and edit the objects, then send it on its way. Since PostScript is homoiconic like Lisp, code and objects are made of arrays and dictionaries, which you could visually browse, edit, and execute. Very much inspired by Smalltalk, but with a twist of Lisp and FORTH!