There have been multiple instances where I had the need to iterate over
type variables, only to discover that the traversal order is arbitrary.
This commit fixes that by adding SortedMapping, which utilizes BTreeMap
internally to guarantee a traversal order. All instances of VarMap are
now refactored to use this to ensure that type variables are iterated in
the order of its variable ID, which should be monotonically incremented
by the unifier.
- Added `Exception` primitive type and some builtin exception types.
Note that all exception types share the same layout, and should
inherit from the base `Exception` type. There are some hacks in the
toplevel module for handling exception types, we should revisit and
fix them later.
- Added new primitive types to concrete type module, otherwise there
would be some weird type errors.
- Changed the representation of strings to CSlice<u8>, instead of
CString.
Previously, we have to copy types from one unification table to another,
and make the table sendable. This requires cloning (processing) the
whole table 3 times per function call which is not efficient and uses
more memory than required when the unification table is large.
We now use a concrete type table to only copy the type we need. This
reduces the overhead as we only need to process the unification table
for once (when we do the function codegen), and reduces memory usage by
a bit (but not noticeable when the unification table is small, i.e. the
types are simple).
David Mak
ychenfo
pca006132
Sebastien Bourdeauducq