Elementary List Operations

refresh print

Elementary List Operations

Creating and Accessing Lists

Creating an integer sequence: <int1>..<int2>

Description: The expression <int1>..<int2> creates a list of consecutive integers starting with <int1> and ending with <int2>. If <int1> is larger than <int2>, then the empty list is returned.

4..9[4, 5, 6, 7, 8, 9]
-2..2[-2, -1, 0, 1, 2]

The length of a list: length(<list>)

Description: This operator returns an integer that is equal to the number of elements in the <list>.

length([2 ,5 ,7 ,3])4
length([2 ,[5, 4, 5] ,7 ,3]_2)3

Combining the length and the repeat operator allows one to list all elements of a list easily.


One word of caution here: CindyScript is designed in such a way that it is seldom useful to traverse all the elements of a list using the repeat operator. There are more elegant ways.

Testing for containment: contains(<list>,<expr>)

Description: This operator returns either true or false depending on whether <list> contains the element <expr>.


List Manipulation

Concatenation of lists: concat(<list1>,<list2>)

Description: This operator creates a list by concatenation of two other lists. This operator can equivalently be written as <list1>++<list2>.

concat(["a", "b"], ["c", "d"])["a", "b", "c", "d"]

Removing elements from lists: remove(<list1>,<list2>)

Description: This operator creates a list by removing all elements that occur in <list2> from <list1>. This operator can equivalently be written as <list1> -- <list2>.

remove([1,3,4,5,1,5,6], [1,3,7])[4,5,5,6]

Intersection of lists: common(<list1>,<list2>)

Description: This operator creates a list collecting all elements that are in both <list1> and <list1>. In the returned list the elements are sorted and each element occurs at most once. This operator can equivalently be written as <list1>~~<list2>.

common([1,3,4,5,1,5,6], [1,3,7])[1,3]

Appending an element: append(<list>,<expr>)

Description: This operator returns a list that is created by appending <expr> to the list <list> as its last element.
This operator can equivalently be written as <list>:><expr>.

append(["a", "b", "c"], "d")["a", "b", "c","d"]
["a", "b", "c"]:>"d"["a", "b", "c","d"]

Prepending an element: prepend(<expr>,<list>)

Description: This operator returns a list that is created by prepending <expr> to the list <list> as its first element.
This operator can equivalently be written as <expr><:<list>.

prepend("d",["a", "b", "c"])["d","a", "b", "c"]
"d"<:["a", "b", "c"]["d","a", "b", "c"]

Traversing Lists

The forall loop: forall(<list>,<expr>)

Description: This operator is useful for applying an operation to all elements of a list. It takes a <list> as first argument. It produces a loop in which <expr> is evaluated for each entry of the list. For each run, the run variable # takes the value of the corresponding list entry.



This code fragment produces the output


The forall loop: forall(<list>,<var>,<expr>)

Description: Similar to forall(<list>,<expr>), but the run variable is now named <var>.

Applying an expression: apply(<list>,<expr>)

Description: This operator generates a new list by applying the operation <expr> to all elements of a list and collecting the results. As usual, # is the run variable, which successively takes the value of each element in the list.

apply([1, 2, 3, 4, 5],#^2)[1, 4, 9, 16, 25]
apply([1, 2, 3, 4, 5],#+5)[6, 7, 8, 9, 10]
apply(1..5, [#,#^2])[[1, 1], [2, 4], [3, 9], [4, 16], [5, 25]]

Applying an expression: apply(<list>,<var>,<expr>)

Description: Similar to apply(<list>,<expr>), but the run variable is now named <var>.

Selecting elements of a list: select(<list>,<boolexpr>)

Description: This operator selects all elements of a list for which a certain condition is satisfied. The condition is supposed to be encoded by <boolexpr>. This expression is assumed to return a <bool> value. As usual, # is the run variable, which successively take the value of all elements in the list.

select(1..10, isodd(#))[1, 3, 5, 7, 9]
select(0..10, #+# == #^2)[0,2]

A high-level application of the select operator is given by the following example:


It produces the output


In this example, first a function divisors(x) is defined by selecting those numbers that divide x without any remainder. Then a function primes(n) is defined that selects all numbers between 1 and n that have exactly two divisors. These numbers are the primes.

Selecting elements of a list: select(<list>,<var>,<boolexpr>)

Description: Similar to select(<list>,<boolexpr>), but the run variable is now named <var>.

Contributors to this page: von Gagern , Kortenkamp and Richter .
Page last modified on Thursday 26 of March, 2015 [21:13:36 UTC] by von Gagern.

The content on this page is licensed under the terms of the License.

free viagra samplehentai girlsmature pussymilfseeker cialis samplescam clip movie nude webcammother incest order viagra online cialis ukanime rapeparis hilton phone numbers viagra alternatives cialis forum cialis free samplehot girls in pantiesmonster of cocks discount cialis cilias free viagra samplesfree chat rooms cilia structurefree cartoon sex comics buy cialis order viagrafree adult videosplump girl gallerypantyhose gallerycum on her face cheapest cialisbisexual moviestampa bukakehuge black cock thumbnails buy cialis onlineporn star cialis drugwomen having sex cheap generic viagra alternative to viagra natural viagra cheap viagraoral sexteen webcam strip videosnude spanish girlserotic sex cams movies viagra side effectscartoon adultdisney sex animenude blonde hairygang bang swinger cialis viagrabisexual free moviesgay twinkswebcam chat live xxxyoung teens order cialislatina girls thongscum loversjapanese girl viagra cheapyoung japanese girlsmr chews asian beavergangbang squadshoshone indiansmature wiveslive webcam chat girlsfree ebony viagra on lineasian ladyboysteen boys viagra pillsself bondage techniques cailisincest familyfree ebony cheap cialisgay amateur cialis genericbusty asian viagra onlinemature breasts viagra for women free viagrabig boobies cialis generic viagragloryhole gaylatinas in thongs female viagraindian tits viagra 6 free samplesamateur upskirt viagra alternativefree xxx video cialis online discountgalleries of teen girls cialis dosage cheap generic cialisparis hilton pornopussy cat dollsbrutal sexgay peopleblack milfsno tits discount viagrablonde hairy pussyshemale animefree hardcore moviesmom strips for sonfat titscelebrity legsdouble anal levitra vs cialis cialis tadalafil cialis cheapgay bdsmcelebrities exposed viagra generic alternatives to viagra viagra canadabestialitypink porn stars viagra jokesclips of teen sexchicks suck horse cock online viagrasex with horsespainful analglory holes floridafree american bukkake cialis online buy viagrabig cock cum free cialisteen gay porn cialis side effects herbal viagra best price viagra purchase cialis cialis soft tabs cialis vs viagrafree fat girl webcamfree porn movie clipsoral penis suckingebony hardcore viagra pricepantyhose crossed legs cialis and levitralesbiennesblonde boobs buy viagra online