Quotes

A quote is code in square brackets that is pushed rather than run. It is also a list, and the same value can be used either way. Flow describes the words that run quotes.

Quotes as code

[ 1 2 + ]           pushes a quote, adds nothing
[ 1 2 + ] do        leaves 3

if, times and the other control words are ordinary words that take quotes and decide when to run them. A defined word is a quote bound to a name:

[ dup * ] :sq

Quotes as lists

[ 1 2 + ] len .             3
[ 1 2 + ] 2 at .            '+

Inside a quote a word is stored as its name, so the + comes back as the symbol '+. Quotes can hold any value, including other quotes.

The list words

Word	Effect
`list`	`... n -- l`	packs the top n values
`range`	`a b -- l`	a up to b-1
`append`	`l x -- list`	x on the end
`cat`	`a b -- c`	joins two lists
`len`	`l -- n`	how many items
`at`	`l i -- x`	item i, from 0
`first`	`l -- x`	the first item
`last`	`l -- x`	the last item
`rest`	`l -- list`	all but the first
`has`	`l x -- 1\|0`	is x in it
`spread`	`l -- ...`	every item onto the stack

Lists are immutable, so these words return new lists and leave the original untouched.

Iterating

[ 1 2 3 ] [ . ] each
[ 1 2 3 ] [ 2 * ] map           [ 2 4 6 ]
1 11 range [ 2 mod 0 = ] filter [ 2 4 6 8 10 ]

The quote given to map must leave exactly one value per item.

Limits

Quotes that are too long, nested too deeply or unbalanced fail with their own messages, listed in errors.