函数,如果expr是racket中的有效布尔表达式,则返回#t
expr=变量| bool literal | not expr |和expr |或expr函数,如果expr是racket中的有效布尔表达式,则返回#t,racket,Racket,expr=变量| bool literal | not expr |和expr |或expr variable = a symbol v for which (is-vble? v) returns #t . bool-literal = "t" | "f" . not-expr = "(" "not" expr ")" . and-expr = "(" expr "and" expr ")" . or-expr = "(" expr "or" e
variable = a symbol v for which (is-vble? v) returns #t .
bool-literal = "t" | "f" .
not-expr = "(" "not" expr ")" .
and-expr = "(" expr "and" expr ")" .
or-expr = "(" expr "or" expr ")" .
implication-expr = "(" expr "-->" expr ")" .
实现函数(is bool expr?expr),如果expr是有效的布尔表达式(如上定义),则返回#t,否则返回#f。例如:
(是布尔表达式吗?'t)
T
(布尔表达式是?’(t或(不是f)))
T
(布尔表达式是?'((p和(p-->f))-->q))
T
(布尔表达式是?'((p和(p-->f))-->q))
T
(这是奶酪鞋串吗?)
F
到目前为止你试过什么?请发布您的代码。您需要“布尔”函数