Accessing sequence elements - Factor Documentation (original) (raw)

Accessing sequence elements
Factor handbook » The language » Collections » Sequence operations

Element access by index, without raising exceptions:
?nth ( n seq -- elt/f )

Concise way of extracting one of the first four elements:

first ( seq -- first )

second ( seq -- second )
third ( seq -- third )
fourth ( seq -- fourth )
?first ( seq -- elt/f )
?second ( seq -- elt/f )

Extracting the last element:

last ( seq -- elt )

?last ( seq -- elt/f )

Unpacking sequences:

first2 ( seq -- first second )

first3 ( seq -- first second third )
first4 ( seq -- first second third fourth )
last2 ( seq -- penultimate ultimate )

See also
nth