2.4.11 Trees

(alphorder x y) → t

x : (atom x)

y : (atom y)

Determines if x is lexicographically less than y. Works on any atomic input.

Examples:

> (alphorder 6 4)

()

> (alphorder 4 6)

t

> (alphorder 4 4)

t

> (alphorder "abc" "bcd")

t

> (alphorder "bcd" "abc")

()

> (alphorder #\a "a")

t

> (alphorder "a" #\a)

()

> (alphorder '(1 2 3) '(4 5 6))

/Users/cce/plt/research/dracula/release/src/language/checkin

g-proc.scm:36:21: Dracula program broke the contract (->

atom? atom? any) on here; expected <atom?>, given: (1 2 3)

(atom x) → t

x : t

Returns true if x is not a cons pair.

Examples:

> (atom 4)

t

> (atom 'hello)

t

> (atom (cons 4 nil))

()

(eq x y) → t

x : t

y : (or (symbolp x) (symbolp y))

Tests two symbols for equality.

Examples:

> (eq 'yes 'yes)

t

> (eq 'yes 'no)

()

> (eq "yes" "yes")

/Users/cce/plt/research/dracula/release/src/language/checkin

g-proc.scm:36:21: Dracula program broke the contract (->r

((x ...) (y ...)) ...) on here; expected <symbolp>, given:

"yes"

(eql x y) → t

x : t

y : (or (eqlablep x) (eqlablep y))

Tests equality of two numbers, symbols, or characters.

Examples:

> (eql 'yes 'yes)

t

> (eql 'yes 'no)

()

> (eql 5 5)

t

> (eql #\a #\b)

()

> (eql #\5 5)

()

> (eql "yes" "yes")

/Users/cce/plt/research/dracula/release/src/language/checkin

g-proc.scm:36:21: Dracula program broke the contract (->r

((x ...) (y ...)) ...) on here; expected <eqlablep>, given:

"yes"

(eqlablep x) → t

x : t

Returns t if and only if x is either a number, a symbol, or a character.

Examples:

> (eqlablep nil)

t

> (eqlablep 4)

t

> (eqlablep #\a)

t

> (eqlablep 'symbol)

t

> (eqlablep "string")

()

(equal x y)

Tests x and y for equality. Returns t if and only if they are the same value.

Examples:

> (equal "yes" "yes")

t

> (equal 'yes "no")

()

> (equal 'yes "yes")

()

(identity x) → t

x : t

The identity function. Returns its argument unchanged.

Examples:

> (identity 'x)

x

(lexorder a b) → t

a : t

b : t

Determines if the two given items are in lexicographic order.

Examples:

> (lexorder 6 4)

()

> (lexorder 4 6)

t

> (lexorder #\a #\b)

t

> (lexorder #\b #\a)

()

> (lexorder 'a 'b)

t

> (lexorder 'b 'a)

()

> (lexorder "abc" "bcd")

t

> (lexorder "bcd" "abc")

()

> (lexorder (list 1 2) (list 3 4))

t

> (lexorder (list 3 4) (list 1 2))

()

(caar x)

(cdar x)

(cadr x)

(cddr x)

(caaar x)

(cdaar x)

(cadar x)

(cddar x)

(caadr x)

(cdadr x)

(caddr x)

(cdddr x)

(caaaar x)

(cdaaar x)

(cadaar x)

(cddaar x)

(caadar x)

(cdadar x)

(caddar x)

(cdddar x)

(caaadr x)

(cdaadr x)

(cadadr x)

(cddadr x)

(caaddr x)

(cdaddr x)

(cadddr x)

(cddddr x)

Shorthand macros for compositions of car and cdr. For instance, (caddr x) is equivalent to (car (cdr (cdr x))).

Examples:
> (defconst *tree*       (cons (cons (cons (cons 0 1) (cons 2 3))                   (cons (cons 4 5) (cons 6 7)))             (cons (cons (cons 8 9) (cons 10 11))                   (cons (cons 12 13) (cons 14 15)))))
> (caar *tree*)
((0 . 1) 2 . 3)
> (cdar *tree*)
((4 . 5) 6 . 7)
> (cadr *tree*)
((8 . 9) 10 . 11)
> (cddr *tree*)
((12 . 13) 14 . 15)
> (caaar *tree*)
(0 . 1)
> (cdaar *tree*)
(2 . 3)
> (cadar *tree*)
(4 . 5)
> (cddar *tree*)
(6 . 7)
> (caadr *tree*)
(8 . 9)
> (cdadr *tree*)
(10 . 11)
> (caddr *tree*)
(12 . 13)
> (cdddr *tree*)
(14 . 15)
> (caaaar *tree*)
0
> (cdaaar *tree*)
1
> (cadaar *tree*)
2
> (cddaar *tree*)
3
> (caadar *tree*)
4
> (cdadar *tree*)
5
> (caddar *tree*)
6
> (cdddar *tree*)
7
> (caaadr *tree*)
8
> (cdaadr *tree*)
9
> (cadadr *tree*)
10
> (cddadr *tree*)
11
> (caaddr *tree*)
12
> (cdaddr *tree*)
13
> (cadddr *tree*)
14
> (cddddr *tree*)
15

(quote ...)

Examples:

> 'a

a

> '(1 2 3 4)

(1 2 3 4)

(quasiquote ...)

Examples:

> `a

a

> `(1 2 3 4)

(1 2 3 4)

(unquote ...)

Examples:

> '(list ,a  b c d)

(list ,a b c d)

(subst new old tree) → t

new : t

old : (eqlablep old)

tree : t

Substitutes every occurrence of old with new in the given tree. Uses eql as the test.

Examples:

> (subst 2 1 (list 1 1 1 3 1 1 1))

(2 2 2 3 2 2 2)

> (subst 'z 'a (list 'a 'b (list 'd 'a (list 'a 'e)) 'a))

(z b (d z (z e)) z)