[Ur] C type for Ur/Web list type

[Artyom Shalkhakov]

Hello all,

I'd like to implement a function having the following type:

> val join : list string -> option string -> string

which would work as follows:

- if second argument is Some, then it's taken as a separator
- otherwise, it's assumed that no separator is necessary
- the list of strings is concatenated into one contiguous string, with
the separator inserted between the consecutive list elements

For instance:

> join [] _(*anything*) ==> ""
> join ["a","b"] None ==> "ab"
> join ["1","2"] (Some ",") ==> "1,2"

I'd like to use C for implementation, and there is this question: what
C types do [list string] and [option string] map to? I think that
[option string] probably maps to a nullable pointer to
uw_Basis_string. What about the list constructor?

-- 
Cheers,
Artyom Shalkhakov