You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
25 lines
601 B
Markdown
25 lines
601 B
Markdown
6 years ago
|
# Booleans
|
||
|
|
|
||
|
|
Racket has two distinguished constants to represent boolean values: `#t`
|
||
|
|
for true and `#f` for false. Uppercase `#T` and `#F` are parsed as the
|
||
|
|
same values, but the lowercase forms are preferred.
|
||
|
|
|
||
|
|
The `boolean?` procedure recognizes the two boolean constants. In the
|
||
|
|
result of a test expression for `if`, `cond`, `and`, `or`, etc.,
|
||
|
|
however, any value other than `#f` counts as true.
|
||
|
|
|
||
|
|
Examples:
|
||
|
|
|
||
|
|
```racket
|
||
|
|
> (= 2 (+ 1 1))
|
||
|
|
#t
|
||
|
|
> (boolean? #t)
|
||
|
|
#t
|
||
|
|
> (boolean? #f)
|
||
|
|
#t
|
||
|
|
> (boolean? "no")
|
||
|
|
#f
|
||
|
|
> (if "no" 1 0)
|
||
|
|
1
|
||
|
|
```
|