Statically type `string.join`
This previously used a contract annotation rather than a type, due to
issue however the annotation wasn't updated after that issue was
closed. This commit fixes that.
else
%blame% (%tag% "not a string" l),
- # using a contract instead of type for now because of https://github.com/tweag/nickel/issues/226
- join | Str -> Array Str -> Str
+ join : Str -> Array Str -> Str
| doc m%"
Joins a array of strings given a seperator.
