character(len=:),allocatable :: s
character(len=1) :: c
s=c
a character is a single character string, not a distinct datataype. See the intrinsics CHAR and ICHAR for converting bytes to characters and characters to integer values
s = [c]
In Haskell, the String type is only an alias for [Char] which means List of chars. Therefore, we only need to construct a character list with a single element.
let s = c
Similarly to python: A character is a single character string, not a distinct datatype.
Strings= c + "";
This "lazy way" is quite common, but slow at runtime.