⍝ Base64 en/decoding:

    base64 0 1 2 3 4 253 254 255 ⍝ encode some octets
AAECAwT9/v8=

    base64 'AAECAwT9/v8='
0 1 2 3 4 253 254 255

    base64 ⎕ucs 'If I were only dafter' ⍝ encode some ASCII text
SWYgSSB3ZXJlIG9ubHkgZGFmdGVy

    ⎕ucs base64 'SWYgSSB3ZXJlIG9ubHkgZGFmdGVy'
If I were only dafter

    base64 'UTF-8' ⎕ucs '+/⍵÷⍴⍵' ⍝ encode some UTF-8 text
Ky/ijbXDt+KNtOKNtQ==

    'UTF-8' ⎕ucs base64 'Ky/ijbXDt+KNtOKNtQ=='
+/⍵÷⍴⍵

    ⍝ Example from Wikipedia article:

    Hobbes ← 'Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.'

    80 wrap Hobbes
Man is distinguished, not only by his reason, but by this singular passion from 
other animals, which is a lust of the mind, that by a perseverance of delight in
the continued and indefatigable generation of knowledge, exceeds the short      
vehemence of any carnal pleasure.                                               

    80 wrap base64 ⎕ucs Hobbes
TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNp
bmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1p
bmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBp
bmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhl
bWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=                                        

    tails ← (0 to ¯4) ↓¨ ⊂¯20↑Hobbes

    ↑ tails
any carnal pleasure.
any carnal pleasure 
any carnal pleasur  
any carnal pleasu   
any carnal pleas    

    ↑ base64∘⎕ucs¨ tails
YW55IGNhcm5hbCBwbGVhc3VyZS4=
YW55IGNhcm5hbCBwbGVhc3VyZQ==
YW55IGNhcm5hbCBwbGVhc3Vy    
YW55IGNhcm5hbCBwbGVhc3U=    
YW55IGNhcm5hbCBwbGVhcw==    

    tails ≡ {⎕ucs base64 base64 ⎕ucs ⍵}¨ tails  ⍝ check round trip.
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