seqlings 3.0.7

Interactive exercises for learning Seq, a stack-based programming language
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: safe-base64-decode ( String -- String )
    encoding.base64-decode
    if
        # Success - string is on stack
    else
        drop "ERROR"
    then
;

: safe-hex-decode ( String -- String )
    encoding.hex-decode
    if
        # Success - string is on stack
    else
        drop "ERROR"
    then
;

: test-errors ( -- )
    "SGVsbG8=" safe-base64-decode
    "Hello" test.assert-eq

    "Not!!!Valid" safe-base64-decode
    "ERROR" test.assert-eq

    "48656c6c6f" safe-hex-decode
    "Hello" test.assert-eq

    "xyz123" safe-hex-decode
    "ERROR" test.assert-eq

    "123" safe-hex-decode
    "ERROR" test.assert-eq
;