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Define an empty list

Assign the variable "list" to a list with no elements
fantom
list := [,]

Define a static list

Define the list [One, Two, Three, Four, Five]
fantom
list := ["One", "Two", "Three", "Four", "Five"]

Join the elements of a list, separated by commas

Given the list [Apple, Banana, Carrot] produce "Apple, Banana, Carrot"
fantom
["Apple", "Banana", "Carrot"].join(", ")

Join the elements of a list, in correct english

Create a function join that takes a List and produces a string containing an english language concatenation of the list. It should work with the following examples:
join([Apple, Banana, Carrot]) = "Apple, Banana, and Carrot"
join([One, Two]) = "One and Two"
join([Lonely]) = "Lonely"
join([]) = ""
fantom
join := |List list -> Str|
{
switch(list.size)
{
case 0: return ""
case 1: return list[0]
case 2: return list.join(" and ")
default: return list[0..-2].join(", ") + ", and " + list[-1]
}
}

echo(join(["Apple", "Banana", "Carrot"]))
echo(join(["One", "Two"]))
echo(join(["Lonely"]))
echo(join([,]))

Produce the combinations from two lists

Given two lists, produce the list of tuples formed by taking the combinations from the individual lists. E.g. given the letters ["a", "b", "c"] and the numbers [4, 5], produce the list: [["a", 4], ["b", 4], ["c", 4], ["a", 5], ["b", 5], ["c", 5]]
fantom
[4,5].each |Int i| { ["a","b","c"].each |Str s| { r.add([i,s]) } }

From a List Produce a List of Duplicate Entries

Taking a list:
["andrew", "bob", "chris", "bob"]

Write the code to produce a list of duplicates in the list:
["bob"]
fantom
nameCounts := Str:Int[:] { def = 0 }
["andrew", "bob", "chris", "bob"].each |Str v| { nameCounts[v]++ }
results := nameCounts.findAll |Int v, Str k->Bool| { v > 1 }.keys
echo(results.join(","))

Fetch an element of a list by index

Given the list [One, Two, Three, Four, Five], fetch the third element ('Three')
fantom
["One", "Two", "Three", "Four", "Five"][2]
["One", "Two", "Three", "Four", "Five"].get(2)

Fetch the last element of a list

Given the list [Red, Green, Blue], access the last element ('Blue')
fantom
["Red", "Green", "Blue"][-1]
["One", "Two", "Three", "Four", "Five"].last

Find the common items in two lists

Given two lists, find the common items. E.g. given beans = ['broad', 'mung', 'black', 'red', 'white'] and colors = ['black', 'red', 'blue', 'green'], what are the bean varieties that are also color names?
fantom
beans := ["broad", "mung", "black", "red", "white"]
colors := ["black", "red", "blue", "green"]
echo(beans.intersection(colors))

Display the unique items in a list

Display the unique items in a list, e.g. given ages = [18, 16, 17, 18, 16, 19, 14, 17, 19, 18], display the unique elements, i.e. with duplicates removed.
fantom
uniqueAges := [18, 16, 17, 18, 16, 19, 14, 17, 19, 18].unique
echo(uniqueAges)

Remove an element from a list by index

Given the list [Apple, Banana, Carrot], remove the first element to produce the list [Banana, Carrot]
fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(0)

Remove the last element of a list

fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(-1)
list := ["Apple", "Banana", "Carrot"]ยจ
list.pop

Rotate a list

Given a list ["apple", "orange", "grapes", "bananas"], rotate it by removing the first item and placing it on the end to yield ["orange", "grapes", "bananas", "apple"]
fantom
list := ["apple", "orange", "grapes", "bananas"]
list.add(list.removeAt(0))

Gather together corresponding elements from multiple lists

Given several lists, gather together the first element from every list, the second element from every list, and so on for all corresponding index values in the lists. E.g. for these three lists, first = ['Bruce', 'Tommy Lee', 'Bruce'], last = ['Willis', 'Jones', 'Lee'], years = [1955, 1946, 1940] the result should produce 3 actors. The middle actor should be Tommy Lee Jones.
fantom
r := [,]
first.size.times |Int i| { r.add([first[i], last[i], years[i]]) }

echo(r)

List Combinations

Given two source lists (or sets), generate a list (or set) of all the pairs derived by combining elements from the individual lists (sets). E.g. given suites = ['H', 'D', 'C', 'S'] and faces = ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A'], generate the deck of 52 cards, confirm the deck size and check it contains an expected card, say 'Ace of Hearts'.
fantom
r := [,]
["2","3","4","5","6","7","8","9","10","J","Q","K","A"].each |Str c|
{ ["H","D","C","S"].each |Str s| { r.add([c,s]) } }

q := ["A","H"]
result := r.contains(q)
echo("Deck size=${r.size}, contains $q? -> $result")

Perform an operation on every item of a list

Perform an operation on every item of a list, e.g.
for the list ["ox", "cat", "deer", "whale"] calculate
the list of sizes of the strings, e.g. [2, 3, 4, 5]
fantom
["ox", "cat", "deer", "whale"].map { it.size }

Split a list of things into numbers and non-numbers

Given a list that might contain e.g. a string, an integer, a float and a date,
split the list into numbers and non-numbers.
fantom
things := ["hello", 25, 3.14, Time.now]
numbers := things.findType(Num#)
nonNumbers := things.exclude { numbers.contains(it) }

Test if a condition holds for all items of a list

Given a list, test if a certain logical condition (i.e. predicate) holds for all items of the list.
fantom
echo([2,3,4].all{ it>1 })

Test if a condition holds for any items of a list

Given a list, test if a certain logical condition (i.e. predicate) holds for any items of the list.
fantom
echo([2,3,4].any{ it==4 })