Hello, your issue may be how you process the dots in the string. Instead of empty characters, you should see them as breaks or spaces.

An arrow's tail must be entirely made up of either - or =. You cannot mix.

In this case you get for >>><.=<=<..=<> :

>   1
>   1
>   1
<   -1
[.=]
<=  -4
<   -1
[..=]
<>  0

Total = -3

You're welcome to provide Rust translation. :)