JNTU B.Tech II PRINCIPLES OF PROGRAMMING LANGUAGES Previous Question Paper (February - 2024 - R15)

An attribute grammar for simple assignment statements, such as x = y + 1, can be defined as follows:

Let assign be the non-terminal for an assignment statement.

Let id be a non-terminal representing an identifier.

Let expr be a non-terminal representing an expression.

The grammar rules are:

Attributes:

• id.lval: boolean, true if the identifier is on the left-hand side of an assignment.
• expr.val: the value of the expression.

Semantic rules:

• For the rule assign ::= id = expr:
• id.lval must be true.
• expr.val is computed.
• The value of expr.val is assigned to the location represented by id.

The factors influencing the writability of a programming language, which refers to how easily a language can be used to construct programs, include:

• Simplicity: A language with a smaller set of fundamental concepts and constructs is generally easier to learn and use.
• Expressiveness: The ability to express a wide range of computations and algorithms concisely and clearly.
• Readability: A language that is easy to read and understand often leads to better writability, as code written by one programmer can be easily understood by others.
• Orthogonality: A set of primitive constructs that can be combined in a small number of ways to achieve all other constructs. This reduces the number of exceptions and special cases.
• Support for Abstraction: The ability to define and use abstract data types and control structures helps in managing complexity.
• Standardization and Tool Support: Well-defined standards and good tool support (compilers, debuggers, IDEs) improve the development experience.