let length: (s: string) => nat
Get the size of a string.
Michelson only supports ASCII strings so for now you can assume that each character takes one byte of storage.
let sub: (offset: nat, length: nat, s: string) => string
Extract a substring from a string based on the given offset and length. For example the string "abcd" given to the function below would return "bc".
let concat: (a: string, b: string) => string
Concatenate two strings and return the result.