Make.Char
Character operations.
Return the character with the given ASCII code. Raise Invalid_argument "Char.chr"
if the argument is outside the range 0--255.
Return a string representing the given character, with special characters escaped following the lexical conventions of OCaml. All characters outside the ASCII printable range (32..126) are escaped, as well as backslash, double-quote, and single-quote.
Convert the given character to its equivalent lowercase character, using the US-ASCII character set.
Convert the given character to its equivalent uppercase character, using the US-ASCII character set.