Carli at 14:32, 17 May 2024

2024-05-17T14:32:04Z

← Older revision		Revision as of 16:32, 17 May 2024
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	= 6		= 6
	As you see in <code>set_assoc</code>, we have a pure functional approach here. Objects are not modified in-place like in languages like Java, JavaScript, Python, C++ or such, but rather we have to construct a modified copy of that value and overwrite it to the original value. The Scheme optimizer will detect if an in-place operation would be safe, too and can optimize this corner case but the language itself prioritizes safety.		As you see in <code>set_assoc</code>, we have a pure functional approach here. Objects are not modified in-place like in languages like Java, JavaScript, Python, C++ or such, but rather we have to construct a modified copy of that value and overwrite it to the original value. The Scheme optimizer will detect if an in-place operation would be safe, too and can optimize this corner case but the language itself prioritizes safety.

			== Code JITing with List Literals ==
			One can construct lists that themselves represent code. You need basically three primitives:

			* List Literals
			* Symbol Literals
			* <code>(cons list [LIST])</code> to insert a list literal into the code

			All other primitive values like strings, numbers etc. will just be passed through without interpretation.
			> (set my_program '('print "Hello World"))
			= (print "Hello World")

			> (eval my_program)
			Hello World

Carli: Created page with "Lists are a powerful feature in Scheme. Lists can express both: Data and Programs. ==List handling== The following list functions can be used: > '(1 2 3) "list literal" = (1 2 3) > (cons 0 '(1 2 3)) "prepend item to list" = (0 1 2 3) > (append '(1 2 3) 4 5) "append items to list" = (1 2 3 4 5) > (has? '(1 2 3) 2) "check if item is in list" = true > (filter '(1 2 3) (lambda (x) (< x 2))) "filter items that are smaller than 2" = (1) > (map '(1 2 3) (l..."

2024-05-17T14:27:01Z

Created page with "Lists are a powerful feature in Scheme. Lists can express both: Data and Programs. ==List handling== The following list functions can be used: > '(1 2 3) "list literal" = (1 2 3) > (cons 0 '(1 2 3)) "prepend item to list" = (0 1 2 3) > (append '(1 2 3) 4 5) "append items to list" = (1 2 3 4 5) > (has? '(1 2 3) 2) "check if item is in list" = true > (filter '(1 2 3) (lambda (x) (< x 2))) "filter items that are smaller than 2" = (1) > (map '(1 2 3) (l..."

New page

Lists are a powerful feature in Scheme. Lists can express both: Data and Programs.

==List handling==
The following list functions can be used:
> '(1 2 3) "list literal"
= (1 2 3)

> (cons 0 '(1 2 3)) "prepend item to list"
= (0 1 2 3)

> (append '(1 2 3) 4 5) "append items to list"
= (1 2 3 4 5)

> (has? '(1 2 3) 2) "check if item is in list"
= true

> (filter '(1 2 3) (lambda (x) (< x 2))) "filter items that are smaller than 2"
= (1)

> (map '(1 2 3) (lambda (x) (* x 2))) "double all numbers"
= (2 4 6)

> (reduce '(1 2 3) + 0) "build sum by starting with 0 and reducing them over (+ 0 value)"
= 6
==Associative Lists (Objects)==
The following functions can be used:
> (set obj '("a" 1 "b" 2 "c" 3)) /* construct object from a list with alternating key-value */
= ("a" 1 "b" 2 "c" 3)

> (obj "a") /* extract a value */
= 1

> (set_assoc obj "a" "5") /* construct a new object with another value */
= ("a" "5" "b" 2 "c" 3)

> (set obj (set_assoc obj "a" "5")) /* modify obj */
= ("a" "5" "b" 2 "c" 3)

> (filter_assoc obj (lambda (key value) (not (equal? key "c")))) /* filter an object by a condition */
= ("a" 1 "b" 2)

> (map_assoc obj (lambda (key value) (* value 2))) /* double all values */
= ("a" 2 "b" 4 "c" 6)

> (reduce_assoc obj (lambda (accumulator key value) (+ accumulator value)) 0) /* sum up all values */
= 6
As you see in <code>set_assoc</code>, we have a pure functional approach here. Objects are not modified in-place like in languages like Java, JavaScript, Python, C++ or such, but rather we have to construct a modified copy of that value and overwrite it to the original value. The Scheme optimizer will detect if an in-place operation would be safe, too and can optimize this corner case but the language itself prioritizes safety.

Lists and Objects - Revision history

Carli at 14:32, 17 May 2024