List

Lists are collection objects that contain a sequence of values each associated with an integer index.

Create a list like this:

var list = [1, 2, 3]

Look up values using index notation:

list[0]

Indexing can also be done with slices: list[0..2] list[[0,1,3]]

You can change list entries like this:

list[0] = "Hello"

Create an empty list:

var list = []

Loop over elements of a list:

for (i in list) print i

Append

Adds an element to the end of a list:

var list = []
list.append("Foo")

Insert

Inserts an element into a list at a specified index:

var list = [1,2,3]
list.insert(1, "Foo")
print list // prints [ 1, Foo, 2, 3 ]

Pop

Remove the last element from a list, returning the element removed:

print list.pop()

If an integer argument is supplied, returns and removes that element:

var a = [1,2,3]
print a.pop(1) // prints '2'
print a        // prints [ 1, 3 ]

Sort

Sorts the contents of a list into ascending order:

list.sort()

Note that this sorts the list "in place" (i.e. it modifies the order of the list on which it is invoked) and hence returns nil.

You can provide your own function to use to compare values in the list

list.sort(fn (a, b) a-b)

This function should return a negative value if a<b, a positive value if a>b and 0 if a and b are equal.

Order

Returns a list of indices that would, if used in order, would sort a list. For example

var list = [2,3,1]
print list.order() // expect: [2,0,1]

would produce [2,0,1]

Remove

Remove any occurrences of a value from a list:

var list = [1,2,3]
list.remove(1)

ismember

Tests if a value is a member of a list:

var list = [1,2,3]
print list.ismember(1) // expect: true

Add

Join two lists together:

var l1 = [1,2,3], l2 = [4, 5, 6]
print l1+l2 // expect: [1,2,3,4,5,6]

Tuples

Generate all possible 2-tuples from a list:

var t = [ 1, 2, 3].tuples(2)

produces [ [ 1, 1 ], [ 1, 2 ], [ 1, 3 ] ... ].

Sets

Generate all possible sets of order 2 from a list.

var t = [ 1, 2, 3 ].sets(2)

produces [ [ 1, 2 ], [ 1, 3 ], [ 2, 3 ] ].

Note that sets include only distinct elements from the list (no element is repeated) and ordering is unimportant, hence only one of [ 1, 2 ] and [ 2, 1 ] is returned.