It's redundant, since you can always compute them from the variable, and it
makes the code that deals with actuals rather cleaner.
On the other hand, it slightly complicates some of the tests, because any names
you use in an Actual need to be defined...
Various infrastructure too to support these.
Doing A.ForEach raised an interesting question: what does it work over? In
plain occam it'd just be arrays, but it should obviously work for lists too.
This suggests that Size and Subscript should work on lists as well, since
ForEach will be implemented in terms of them. I've therefore introduced the
idea of a "sequence" class of types.
This used not to be a problem, but there's now quite a lot of stuff predefined
in the state when testing the typechecker, so it tends to obscure the real
error...
This provides gmapMFor and gmapMFor2, which are like gmapM, but know what
they're looking for, and can therefore avoid going down branches of the tree
that won't contain any interesting types.
The basic approach is quite similar to Uniplate's PlateData: there's a function
(containsType) that'll tell you whether one type is contained somewhere within
another. However, unlike Uniplate, we build a static IntMap IntSet of the types
we need to know about, which allows rather quicker lookups. (I did try using
PlateData first.)
The result is that applyDepthM is now much quicker than it was before.
applyDepthM2 is a bit less impressive, which I assume is because it can't
really prune the tree much if it's looking for two types.
Future enhancements:
- convert more passes to use applyDepthM*;
- make gmapMFor* aware of constructors rather than just types, which should
allow a bit more pruning.
This touches an awful lot of code, but cgtest07/17 (arrays and retyping) pass.
This is useful because there are going to be places in the future where we'll
want to represent dimensions that are known at runtime but not at compile time
-- for example, mobile allocations, or dynamically-sized arrays. It simplifies
the code in a number of places.
However, we do now need to be careful that expressions containing variables do
not leak into the State, since they won't be affected by later passes.
Two caveats (marked as FIXMEs in the source):
- Retypes checking in the occam parser is disabled, since the plan is to move
it out to a pass anyway.
- There's some (now very obvious) duplication, particularly in the backend, of
bits of code that construct expressions for the total size of an array
(either in bytes or elements); this should be moved to a couple of helper
functions that everything can use.
This means all the tests now get run as part of one list, and HUnit keeps track
of the number of failures for us. (The reason I was doing this was so that
tocktest will exit non-zero on QuickCheck test failure too.)
As part of this, I've reworked TestMain's main function quite a bit. It'll now
filter QuickCheck tests into response to options too.
