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Using PLY, write an interpreter for the language of "LISP expressions". ALISP expression is defined as follows: 1. A number (integer as well as fractional) is a LISP expression. 2. if E1 and E2 are LISP expressions then so are (+ E1 E2), (- E1 E2). (*E1 E2), and (/ E1 E2). 3. if L is a LIST expression (defined below) then (car L) is a LISP expression. 4. if B is a BOOLEAN expression and E1 and E2 are LISP expressions then (if B E1 E2) is a LISP expression. ALIST Expression is defined as follows: 1. if E1, E2, ., En are LISP expressions where n>=0 then (E1 E2 . En) is a LIST expression. 2. if L is a LIST expression then (cdr L) is a LIST expression. 3. if E is a LISP expression and L is a LIST expression then (cons E L) is a LIST expression.

Using PLY, write an interpreter for the language of "LISP expressions". ALISP expression is defined as follows: 1. A number (integer as well as fractional) is a LISP expression. 2. if E1 and E2 are LISP expressions then so are (+ E1 E2), (- E1 E2). (*E1 E2), and (/ E1 E2). 3. if L is a LIST expression (defined below) then (car L) is a LISP expression. 4. if B is a BOOLEAN expression and E1 and E2 are LISP expressions then (if B E1 E2) is a LISP expression. ALIST Expression is defined as follows: 1. if E1, E2, ., En are LISP expressions where n>=0 then (E1 E2 . En) is a LIST expression. 2. if L is a LIST expression then (cdr L) is a LIST expression. 3. if E is a LISP expression and L is a LIST expression then (cons E L) is a LIST expression.

Database System Concepts
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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PLEASE how do I write the Evaluation Fonction tree in PLY (Python) for this? (to evaluate the number, the boolean,car, cons, and cdr expressions)

I already have built the lexer and Parser.

Thanks

Using PLY, write an interpreter for the language of "LISP expressions". ALISP expression is defined as follows: 1. A number (integer as well as fractional) is a LISP expression. 2. if E1 and E2 are LISP expressions then so are (+ E1 E2), (- E1 E2), (*E1 E2), and (/ E1 E2). 3. if L is a LIST expression (defined below) then (car L) is a LISP expression. 4. if B is a BOOLEAN expression and E1 and E2 are LISP expressions then (if B E1 E2) is a LISP expression. ALIST Expression is defined as follows: 1. if E1, E2, ., En are LISP expressions where n>=0 then (E1 E2 . En) is a LIST expression. 2. if L is a LIST expression then (cdr L) is a LIST expression. 3. if E is a LISP expression and L is a LIST expression then (cons E L) is a LIST expression. A BOOLEAN expression is defined as follows: 1. True and False are BOOLEAN expressions. 2. if E1 and E2 are LISP expressions then (> E1 E2), (>= E1 E2), (<E1 E2), (<= E1 E2), (= E1 E2), and (<> E1 E2) are BOOLEAN expressions. 3. if B1 and B2 are BOOLEAN expressions then so are (not B1), (and B1 B2), and (or B1 B2). Here are examples of valid LISP expressions: 34 True (20 30 40) (+ 20 30) (* (+ 1 2) (/ 8 4)) (* (car (2 4 (+ 2 4) 8)) (/ 27 9)) (+ (car (2 3 4)) (car (cdr (cdr (9 8 7 6))))) (if (> 2 3) 40 50) (and (> 2 3) (> 3 2)) (cdr (cons (+ 2 3) (4 5 6)))
Transcribed Image Text:Using PLY, write an interpreter for the language of "LISP expressions". ALISP expression is defined as follows: 1. A number (integer as well as fractional) is a LISP expression. 2. if E1 and E2 are LISP expressions then so are (+ E1 E2), (- E1 E2), (*E1 E2), and (/ E1 E2). 3. if L is a LIST expression (defined below) then (car L) is a LISP expression. 4. if B is a BOOLEAN expression and E1 and E2 are LISP expressions then (if B E1 E2) is a LISP expression. ALIST Expression is defined as follows: 1. if E1, E2, ., En are LISP expressions where n>=0 then (E1 E2 . En) is a LIST expression. 2. if L is a LIST expression then (cdr L) is a LIST expression. 3. if E is a LISP expression and L is a LIST expression then (cons E L) is a LIST expression. A BOOLEAN expression is defined as follows: 1. True and False are BOOLEAN expressions. 2. if E1 and E2 are LISP expressions then (> E1 E2), (>= E1 E2), (<E1 E2), (<= E1 E2), (= E1 E2), and (<> E1 E2) are BOOLEAN expressions. 3. if B1 and B2 are BOOLEAN expressions then so are (not B1), (and B1 B2), and (or B1 B2). Here are examples of valid LISP expressions: 34 True (20 30 40) (+ 20 30) (* (+ 1 2) (/ 8 4)) (* (car (2 4 (+ 2 4) 8)) (/ 27 9)) (+ (car (2 3 4)) (car (cdr (cdr (9 8 7 6))))) (if (> 2 3) 40 50) (and (> 2 3) (> 3 2)) (cdr (cons (+ 2 3) (4 5 6)))
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