The following is a description for “JH-Lisp2”, which is a modified version of the language previously described in homework 3, problem 6:
(a) The alphabet of JH-Lisp2 consists of the open ’[’ and close ’]’ square brackets,
the digits 0-9, the underscore character ’ ’, and the letters {a, b,d, i,l, m,o, s,u, v}
(b) An operator is a substring in JH-Lisp2 containing one of the following strings:
{add, sub, mul, div, mod}.
(c) A number is a substring in JH-Lisp2 containing one or more of the digits 0-9
(d) An expression is defined as either a number or a list expression
(e) A list expression is defined by the following, in order:
i. An open bracket: ’[’
ii. An operator
iii. An underscore: ’ ’
iv. An expression
v. An underscore: ’ ’
vi. An expression
vii. A close bracket: ’]’
(f) A string in the JH-Lisp2 language is a single list expression.
An example string in this language might be [add [mod 4 3] 21]
Give a context-free grammar for JH-Lisp2.