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Comment by adregan | Hacker News Reader

> Or less drastically, an IDE for APL beginners: symbols have human language helpers or UI overlays

Dyalog, which maintains a commercial APL, provides a free development environment which does exactly what you want[0]. You can hover over all of the available glyphs for documentation.

It’s a really fun development environment in that it does something that I’ve never really experienced in any another: you can modify prior inputs to experiment with new ideas.

Playing with APL (it often does feel like play, or even sculpting with clay) is really fun. Be careful, you might get attached!

0: https://www.dyalog.com/

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> you can modify prior inputs to experiment with new ideas

having trouble understanding what is meant. like, changing things like in excel?

Try that experience at https://tryapl.org

Enter 1+2 where the cursor is below the copyright notice.

Now click or use arrow keys to navigate up and change the 2 to a 4 and hit Enter again.

i mean that's cool, but from my background i would say since the input is "variable", assign it to a named variable and run the function with the variable assigned to 2, then again with it assigned to 4. that's doable in most any REPL.

or even take the function, and map a range of values to the function, to get a range of outputs. again, doable in most REPLs where the language supports some sort of mapping syntax.

can you help me understand what makes this unique? i'm not an APL user, so maybe it's just a different mindset altogether that i'm missing.

APL was one of the first interactive environments along with Lisp. They've had this back when you had a typewriter with a rotating ball with the symbols connected to the time share computer. So you'd type an expression on the typewriter, computer would run it, and it would be printed on actual paper lol.

With APL you can also do the stuff you're referring to by creating a function and mapping it to a list of numbers. If you're familiar with REPLs, the experience is similar.

This thing of having a screen editor where you could move the cursor and execute any command instead of a linear terminal was a staple of 1970's and 1980's computers. Oberon also is notable for letting you execute code written anywhere (and so allowing code to be used as command palettes or menus)

You know how in a typical REPL, you’ll make use of the up arrow to repeat a previously executed expression?

Dyalog allows you to click on the previously printed expression, modify it in place and when you hit enter, it’ll evaluate as if entered on the read line.

It’s a simple little feature but it makes everything feel so malleable.

You beat me to saying the same thing lol. Their IDE is pretty helpful.

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