Since Python doesn't have a
char type, an element of
str is always
'@pythonetc' # '@'
This is an infinite type and you can't construct in a strictly typed language (and why would you?) because it's unclear how to construct the first instance (thing-in-itself?). For example, in Haskell:
Prelude> str = str str <interactive>:1:7: error: • Occurs check: cannot construct the infinite type: t1 ~ t -> t1