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PeterBartholomew1's avatar
PeterBartholomew1
Silver Contributor
Sep 06, 2026

I decided to look at the possibility of extending my conversion to Braille to cover multiline phrases.

The thing I like about using Lambda solutions is that such changes can sometimes be made based upon very localised edits.

WRITEλ = LAMBDA(message, 
//  This function reads a text message and return the corresponding Braille letters
    LET(
        chars,   MAPλ(message, LAMBDA(line, REGEXEXTRACT(line,".",1))),
        charLst, TILECHARλ(BrailleTable, 4, 2),
        Braileϑ, TILEλ(BrailleTable, 4, 2),
        return,  XLOOKUP(chars,charLst,Braileϑ, THUNK("")),
        EVALTHUNKARRλ(return)
    )
);

The changes required were to use MAPλ to allow REGEXEXTRACT to return multiple rows of characters and to allow for a null thunk to be returned for a missing matches.

djclements's avatar
djclements
Silver Contributor
Sep 09, 2026

PeterBartholomew1​ 

Very slick! I'm beginning to appreciate the method to your madness. ;)

My Lambda wasn't quite as easy to edit as yours, but it wasn't too bad either. I just had to broaden the Kronecker product explosion when writing, and MAP over 'slices' when reading.

// Part 1:

= BRA2TXT(SLICEROWS(braille,4,3), TOCOL(SLICEROWS(alphabet,4,1),1), BRA2BIN(SLICEROWS(alphabet,4,-3)))

// Part 2:

= BRA2TXT(words, TOCOL(SLICEROWS(alphabet,4,1),1), BRA2BIN(SLICEROWS(alphabet,4,-3)), 1)

// Where:

BRA2BIN = LAMBDA(ref,
    BYROW(WRAPROWS(LEN(TOCOL(ref, , 1)), 6), CONCAT)
);

BRA2TXT = LAMBDA(phrase,chr_array,bin_array,[text_to_braille],
    IF(
        text_to_braille,
        LET(
            i, SEQUENCE(ROWS(phrase)),
            j, SEQUENCE(MAX(LEN(phrase))),
            DROP(IF(MID(
                INDEX(XLOOKUP(MID(phrase, TOROW(j), 1), chr_array, bin_array, "000000"), TOCOL(i * EXPAND(1, , 4, 1)), TOROW(j * EXPAND(1, , 2, 1))),
                TOCOL(i ^ 0 * EXPAND(SEQUENCE(1, 3), , 4, 9)) + TOROW(j ^ 0 * EXPAND(0, , 2, 3)), 1) = "1", "●", ""
            ), -1)
        ),
        MAP(SEQUENCE(AREAS(phrase)), LAMBDA(area_num, TRIM(CONCAT(XLOOKUP(BRA2BIN(INDEX(phrase, , , area_num)), bin_array, chr_array)))))
    )
);

SLICEROWS = LAMBDA(range,size,[keep],
    IF(
        ROWS(range) > size,
        REDUCE(
            TAKE(TAKE(range, size), keep),
            SEQUENCE(ROUNDUP(ROWS(range) / size, 0) - 1, , size, size),
            LAMBDA(ref,num,
                (ref, TAKE(TAKE(DROP(range, num), size), keep))
            )
        ),
        TAKE(range, keep)
    )
);

Not a winner in ingenuity by any means, but it was a fun experiment. :)