Multi-line inputs in RIDE (APL)?

Question

I wish to type in a multi-line array as follows:

ast ← ('∘'
           ('a' ('p'))
           ('b' 
             ('q' ('v'))
             ('r'))
           ('c' 
             ('s' ('w' 'x'))
             ('t' ('y' 'z'))))

This is correctly paranthesized, but I am unable to copy-paste it into the Dyalog APL RIDE interface. I searched around, and found two answers both of which do not help me:

A github issue: Unable to paste any DFN from dfns website asks about pasting DFNS, which explains that one can use ∇. When I type the ∇, the UI of the text-box changes and becomes dark gray, which is encouraging, but on typing ast ← { <ENTER> or ast ← ( <ENTER> it errors out.
This SO question on multi-line text values in APL asks how to input text. I tried to use the { } method, but when I type ast ← { <ENTER> it already errors out.

So, how does one type multiline data in APL?

score 2 · Accepted Answer · answered Mar 06 '20 at 08:03

The session doesn't currently support multi line arrays.

For now, you still have to create multi dimensional arrays programmatically for the most part (although you can, for example, create an editable text matrix, fill it with "numbers" and then use ⍎¨)

cmat←⍪''
)ed cmat

paste this

0123
2314
1244

then fix it (press Esc) and use

      ⍎¨cmat

For me, I find Shift-Enter and Ctrl-Enter are my best friends most of the time

It looks like you're trying to represent a tree as a nested array (look at dfns tview and tnest and other tree stuff for more on that). As such, it doesn't look like you really need multiline (all arrays in APL are hyperrectangular)?

ast←('∘'('a' ('p'))('b'('q'('v'))('r'))('c'('s' ('w' 'x'))('t' ('y' 'z'))))

Traditional functions (tradfns) can be copy and pasted readily, if they use the session input format:

     ∇ r ← larg Fun rarg
     r ← larg, rarg
     ∇

Multi-line dfns can be pasted. First use the ]dinput user command.

      ]dinput

then paste

      dfn ← {
   ⍺, ⍵
}

(btw, regarding ∇ from the previous comment, you can paste the multiline dfn and prepend with ∇, but you have to put ∇ on the last line [n] and press enter for it to fix the function. The ]dinput user command is a bit simpler)

Thanks! I wanted the multi-line view to think about the it when I input my data into APL — Siddharth Bhat, Mar 06 '20 at 11:25

score 2 · Answer 2 · answered Mar 06 '20 at 09:08

In addition to Richard Park's excellent answer, it should be noted that Dyalog is working on multi-line arrays on two fronts:

Designing a new multi-line array notation

The newest edition was presented in 2018
⎕SE.Link.Serialise can create multi-line notation from most any array
⎕SE.Link.Deserialise will return the array specified by its argument notation array

Multi-line session input

Version 18.0 (due summer 2020) includes experimental multi-line session support. It has to be enabled with a configuration parameter.
It will detect unfinished dfns (e.g. MyFn←{ and 4{) and control structures (e.g. :If myVar>5 and :Class MyCl) but not array notation.
18.0 will also contain a tool, ⎕SE.Link.Array which allows wrapping multi-line array notation in a dfn:

{
 [1 2 3
  4 5 6]
}⎕SE.Link.Array⍬

Multi-line inputs in RIDE (APL)?

2 Answers2

Designing a new multi-line array notation

Multi-line session input