to gc:cons and gc:closure instead of passing locs
This enables the important change, namely that get-root-set
no longer returns roots corresponding to the arguments
of the allocation function that we're in the middle of.
This means that a common error students have (forgetting
to chase the 'hd' and 'tl' pointers in their GC) is
harder to make now, since get-root-set never contains
those locations as roots. (In the past you would have had
to write some pretty non-obvious mutator program to get
that behavior.)
generate so much code
(Mostly to avoid pain with the macro stepper, but also
reducing the amount of code macros generates is good
for performance reasons)
The code used to avoid lifting identifier in more restricted circumstances,
but it seems safe to alway avoid that, which can lead to a lot
less lifting
This is mostly to better support test cases so that we
can set up namespaces that have specific collectors in them
(easiest to do with quote-based requires)
- give names to user functions that matches the user's names
(if the third bullet goes away, then the function
mutator-lift needs to be adjusted so that it uses
procedure-rename in order to preserve the improvement
in this bullet)
- change exn? to exn:fail? (to avoid catching break exns)
- change lang so that primitives (the ones in the
provide-flat-prims/lift declaration) are not allocated
in the user's space (treat them as if they are constants)
This change makes it easier to build up and explain the
GC api, piece by piece. That is, you can first run a program
that contains just a constant (and explain it) with only a
subset of the api. Then you can do something like (+ 1 2)
and explain it, both without getting into how procedures work.
(This is helpful for the way I run my lectures)
