Factor/GSoC/2010/Destructuring locals bindings

Mentors

Slava Pestov

Joe Groff

Technical outline

Factor has a locals library which implements lexical variables and closures over the underlying stack-based computation model. It adds simple syntax for lexical variable bindings that integrates into the surrounding concatenative model:

1 2 + :> three ! bind 3 to "three"
3 4 [ + ] [ - ] 2bi :> ( seven negone ) ! bind 7 and -1 to "seven" and "negone"

It also provides a mechanism for building datastructures from lexical values using literal syntax:

1 2 + :> three
{ three 4 5 } ! evaluates to { 3 4 5 }

The locals syntax currently lacks the ability to destructure aggregates. The syntax could be extended to destructure common classes of Factor aggregates, such as sequences, assocs, and tuples:

3 iota :> { zero one two } ! bind zero, one, and two to 0, 1, and 2
image new
    RGBA >>component-order
    unsigned-char >>component-type
    :> T{ image { component-order order } { component-type type } }
    ! bind "order" to RGBA and "type" to unsigned-char

This revision created on Thu, 4 Mar 2010 00:22:52 by jckarter