since the memory cell is suppost to hold a value from 0-255, you can assume an extended ascii-set.

As far as encoding goes, you have to handle the ascii -> utf-8 encoding yourself (It's easier than it might look like).

Hint: char

In Rust String is always valid UTF-8. &[u8] (slice of bytes) is called byte-string and ascii encoded. It can be created with b"Hello" instead of "Hello". Vec<u8> (vector of bytes) is the owned version of a byte-string, like String is the owned version of &str.

When using String as input, we would have to restrict ourselves to bytes in the range 0-127 or explain the user that they have to convert the input to an acsii-encoded byte-string before reading the bits. Same goes for the output, since the native approach to convert a byte-string to a string String::from_uft8(s).unwrap() breaks as soon as characters from the extended set (128-255) are present in the string. A correct conversion would have to first convert the bytes to chars (4-byte Unicode scalar values) and then to String (looks something like this s.into_iter().map(|b| b as char).collect()).

I'm not sure what's the best choice, but using String will definitly confuse some people and require additional explanation.
Let me know, what you think. (The brainfuck Kata also uses Vec<u8>for input/output )

@donaldsebleung,

random testing is now available in rust, so I went ahead and updated my translation.

Seeing forward to your feedback,
Blablubqq

The rust translation uses assert_eq! instead of assert_fuzzy_equals for the random tests.
That's why some solutions work for other languages but not for rust.

(I submitted a fork to fix that problem)

The current version of rust doesn't use assert_fuzzy_equals() in random_tests() and therefore only allows the answer x / ((1.0 + x).sqrt() + 1.0).

Other approximate solutions like using the Taylor series should be accepted, too.

@donaldsebleung,

no offense taken.

I will keep my eye on the issue and update my translation, once the problem has been resolved.

Thanks for the great Kata, I highly enjoyed the series.