Version: 4.2
1.4.1 Booleans
| t : booleanp |
The boolean truth value.
| nil : booleanp |
The boolean falsehood value.
| (and bool ) |
Returns nil if and only if one or more of its arguments is nil. Otherwise, returns the last argument given. If given no arguments, returns t.
Examples: |
| > (and) |
t |
| > (and t t t) |
t |
| > (and t nil t) |
() |
| > (and 1 2 3 4 5) |
5 |
| (booleanp x) → t |
| x : t |
Determines if x is either t or nil.
Examples: |
| > (booleanp t) |
t |
| > (booleanp nil) |
t |
| > (booleanp 'yes) |
() |
| (iff p q) → t |
| p : t |
| q : t |
Returns t if and only if p and q are either both nil or both non-nil.
Examples: |
| > (iff t t) |
t |
| > (iff nil nil) |
t |
| > (iff t nil) |
() |
| > (iff nil t) |
() |
| > (iff 5 6) |
t |
| > (iff 5 nil) |
() |
| (implies p q) → t |
| p : t |
| q : t |
Returns nil if and only if q is nil and p is non-nil. Otherwise, returns t.
Examples: |
| > (implies t t) |
t |
| > (implies t nil) |
() |
| > (implies nil t) |
t |
| > (implies nil nil) |
t |
| (not x) → t |
| x : t |
If x is nil, then returns t. Otherwise, returns nil.
Examples: |
| > (not t) |
() |
| > (not nil) |
t |
| > (not 5) |
() |
| > (not 0) |
() |
| (or x ) |
Returns t if and only if one or more of its arguments is t. Otherwise, returns the last argument given. If given no arguments, returns nil.
Examples: |
| > (or) |
() |
| > (or nil nil t) |
t |
| > (or nil nil 5 6) |
5 |