1. Open terminal.
2. Go to the directory containing all files.
3. Run "sudo sml rational.sml".
4. Type your password and press enter key.

OR

3. Run "sudo sml".
4. Type your password and press enter key.
5. Run "CM.make "makefile.cm";".
6. Run "Calc.parse();".

1. Type your expression, add a semicolon at the end then press enter.
2. Your expression can include:
   • Binary operators: "+", "-", "*" and "/"
   • Negation: "~" (Warning: Not a operator, can only be used on values)
   • Integers: Use "~" instead of "-" to denote negative numbers.
   • Decimals: In the fractional-normal form.(Use "~" instead of "-" to denote negative numbers)

Rational ::= "~" rational | rational
rational ::= integer | decimal | fraction
integer ::= digit | digitinteger
decimal ::= integer "." integer "(" integer ")" | "." integer "(" integer ")" | integer "." "(" integer ")"
fraction ::= integer "/" nonzerointeger
nonzerointeger ::= integer positivedigits
positivedigits ::= "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
digit ::= positivedigits | "0"

NUM ::= integer | "" integer | decimal | "" decimal
integer::= digit | digit integer
decimal::= integer "." integer "(" integer ")" | "." integer "(" integer ")" | integer "." "(" integer ")"
digit ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

(fractions are not implemented in parser as their functionality is obtained through dividing)

Start ::= Expression ";"
Expression ::= Term | Term "+" Term | Term "-" Term
Term ::= Rat | Rat "*" Rat | Rat "/" Rat
Rat ::= RAT | variable
RAT ::= Rational | "(" Expression ")"
variable ::= alphabet | alphabet integer | alphabet integer variable
alphabet ::= “A” | “B” | “C” | “D” | “E” | “F” | “G” | “H” | “I” | “J” | “K” | “L” | “M” | “N” | “O” |
“P” | “Q” | “R” | “S” | “T” | “U” | “V” | “W” | “X” | “Y” | “Z” | “a” | “b” | “c” | “d” |
“e” | “f” | “g” | “h” | “i” | “j” | “k” | “l” | “m” | “n” | “o” | “p” | “q” | “r” | “s” |
“t” | “u” | “v” | “w” | “x” | “y” | “z”

START ::= EXP ";" EXP ::= NUM | EXP "+" EXP | EXP "-" EXP | EXP "*" EXP | EXP "/" EXP | "(" EXP ")"
(The rules for associativity and precedence are mentioned separately in the parser)

I have used the resources present in the SMLNJ Documentation of ML lex and ML yacc. Namely the base structure for the parser as present in the Rational_parser.lex, Rational_parser.grm, Rational_parser.sml files is taken from the above mentioned source.