cols←{⎕ML←1                         ⍝ Multi-column display.

    ⍺←1 ⎕PW                         ⍝ default inter-column-gap and max-width.

    split←{(+/∨\' '≠⌽⍵)↑¨↓⍵}        ⍝ without-trailing-blanks-split (idiom).

    1<⍴⍴⍵:⍺ ∇ split ⍵               ⍝ char matrix: use the split vector.

    maxcols←{                       ⍝ maximum number of cols.
        ⍵=0:0                       ⍝ one or more items too wide: stop.
        nr xs←|0 ⍵⊤-ni              ⍝ number of rows and excess.
        xs≥nr:∇ ⍵-1                 ⍝ one or more empty columns: ignore.
        ms←⍵ nr⍴lens                ⍝ matrix of sizes.
        wid←(gap×⍵-1)++/⌈/ms        ⍝ total width.
        wid≤max:⍵                   ⍝ it fits: hurrah!
        ∇ ⍵-1                       ⍝ otherwise, try one less column.
    }

    reshape←{                       ⍝ ⍺-col reshape of ⍵.
        ⍺=0:↑max↑¨↓col ⍵            ⍝ item too wide: truncated single col.
        nr←⌈ni÷⍺                    ⍝ number of rows.
        matr←⍺ nr⍴(⍺×nr)↑⍵,⍺/' '    ⍝ matrix blank-padded to whole no of cols.
        pads←↑nr/↓gap/' '           ⍝ inter-column padding.
        ↑{⍺,pads,⍵}/col¨↓matr       ⍝ gap-spaced cols.
    }

    col←⍕∘{1=≡⍵:⍪⍵ ⋄ ↑⍵}            ⍝ formatted numeric or char-vecs column.

    gap max←2↑⍺,⎕PW                 ⍝ inter-column-gap and max-width.
    ni←≢⍵                           ⍝ number of items.
    lens←(2×≢⍵)↑,↑⍴¨⍕¨⍵             ⍝ item-lengths.
    ulim←⌈max÷1⌈gap+⌊/ni↑lens       ⍝ cols: upper limit for search.

    (maxcols ulim)reshape ⍵         ⍝ multi-column display.
}

code_colours

test script

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