Design of new programming languages using bnf

A fascinating topic!

Designing a new programming language using Backus-Naur Form (BNF) is a challenging but rewarding task. Here's a step-by-step guide to help you get started:

Step 1: Define the language's goals and scope

Before designing the language, identify its purpose, target audience, and the problems it aims to solve. This will help you determine the language's features, syntax, and semantics.

Step 2: Choose a BNF notation

There are several BNF notations available. For this example, we'll use the ISO 14977:1996 standard, which is widely used and supported by most text editors and compilers.

Step 3: Define the language's syntax

Using BNF, define the language's syntax by specifying the production rules for each construct. A production rule consists of a non-terminal symbol (left-hand side) and one or more terminal symbols (right-hand side) separated by whitespace.

For example, let's define a simple arithmetic language called "Arith":

Arith ::= Expression
Expression ::= Term ((ADD | SUB) Term)*
Term ::= Factor ((MUL | DIV) Factor)*
Factor ::= NUMBER | VARIABLE | LPAREN Expression RPAREN
ADD ::= '+'
SUB ::= '-'
MUL ::= '*'
DIV ::= '/'
NUMBER ::= [0-9]+
VARIABLE ::= [a-zA-Z][a-zA-Z0-9]*
LPAREN ::= '('
RPAREN ::= ')'

In this example, Arith is the start symbol, and Expression is the first production rule. The Expression rule is defined as a sequence of Terms separated by ADD or SUB operators. The Term rule is defined as a sequence of Factors separated by MUL or DIV operators. And so on.

Step 4: Define the language's semantics

Once you have defined the syntax, you need to specify the semantics of each construct. This includes the meaning of each production rule, the evaluation order, and any side effects.

For example, in the Arith language, the ADD and SUB operators have the following semantics:

• ADD and SUB have the same precedence and are evaluated from left to right.
• The ADD operator returns the sum of its operands, and the SUB operator returns the difference of its operands.

Step 5: Implement the language

Using the BNF definition and the semantics, implement the language by writing a parser, an interpreter, or a compiler. You can use a parser generator tool like ANTLR, yacc, or lex to help you with the implementation.

Step 6: Test and refine the language

Test the language with a set of examples and edge cases to ensure it works as expected. Refine the language by fixing bugs, adding features, and improving performance.

Here's an example of a simple Arith interpreter written in Python:

import re

class Arith:
    def __init__(self, input_string):
        self.input_string = input_string
        self.tokens = self.tokenize()

    def tokenize(self):
        tokens = []
        for token in re.split(r'(\+|-|\*|/|\(|\))', self.input_string):
            if token:
                tokens.append(token)
        return tokens

    def evaluate(self):
        result = 0
        for token in self.tokens:
            if token in ['+', '-', '*', '/']:
                op = token
                operand1 = result
                result = 0
            elif token.isdigit():
                result = int(token)
            elif token.isalpha():
                result = float(token)
            else:
                raise ValueError(f"Invalid token: {token}")
        return result

# Example usage:
arith = Arith("2 + 3 * 4")
print(arith.evaluate())  # Output: 14.0

This is a basic example, and you can improve it by adding more features, error handling, and optimization.

Conclusion

Designing a new programming language using BNF is a challenging but rewarding task. By following these steps, you can create a language that is easy to use, efficient, and scalable. Remember to test and refine your language to ensure it meets the needs of its users. Happy coding!