Interpreter in Haskell

An interpreter written in Haskell for a Python like language.

Examples of Valid Expressions

    1.  
        { 
            num = 5; 
            str = "First Program"; 
            print(str);

            if (num > 3)  
                { 
                    num = 6; 
                } 
                else 
                { 
                    print(num); 
                } 
        }

    Output : print "First Program"
             num 6


    2.  
        { 
            i = 5;
            a = (4 < 3) || 6 != 7;
            print(a);

            # First While! #
            while(i != 0 && a) 
            { 
                print(i); 
                i = i - 1; 
            }

        }

    Output : a True
             i 0
             print True 5 4 3 2 1 

---

Grammar used for Interpreter

Block 
    : { Part }

Part 
    : Statement Part
    | IfStatement Part
    | WhileLoop Part
    | Comment String Part
    | epsilon

Statement 
    : var = AllExpr;
    | print( AllExpr );

AllExpr 
    : Sentences ++ AllExpr
    | Sentences

Sentenes
    : string
    | LogicExpr

IfStatement
    : if ( LogicExpr ) Block else Block

WhileLoop
    : while ( LogicExpr ) Block 

LogicExpr
    : BoolExpr && LogicExpr
    | BoolExpr || LogicExpr
    | BoolExpr

BoolExpr 
    : True
    | False
    | ArithBoolExpr

ArithBoolExpr
    : Expr > Expr
    | Expr < Expr
    | Expr == Expr
    | Expr != Expr
    | Expr

Expr 
    : HiExpr + Expr
    | HiExpr - Expr
    | HiExpr

HiExpr 
    : SignExpr * HiExpr
    | SignExpr / HiExpr
    | SignExpr % HiExpr
    | SignExpr 

SignExpr
    : int
    | ( AllExpr )
    | var

---

How to Run

$ ghc -o a interpreter.hs
$ ./a