For lack of a better place, I've put it in `Syntax.PreorderReasoning`
These equations are natural in equational reasoning, but less so when
rewriting, so that's why it's there
As it was, it could break if the argument was repeated more than twice.
When checking dot patterns, we need to check that no further holes are
solved, and that the pattern variable doesn't unify with some other
pattern variable, but if it had already made progress (either for a good
or bad reason) we missed this. Fixes#536
As it was, there was significant backtracking for big expressions,
getting to the end, not finding a **, so having to try again for
application expressions. Fixes#532
The timings flag (`--timing`) displays various timing information during the entire compilation process.
This is useful when performing adhoc profiling of the compiler.
However, the information is a mixture of timestamps and relative progress.
The information is inherently nested, and such nesting is not immediatly clear in the output.
This can be confusing.
This minor changes nests the timing information on output so that when aligned one can see the timestamps at the highest level, and progress during the elaboration stage.
This has involved quite a bit of reorganisation and some improvements in
resugaring so that the results look nice. In summary:
* Expression search now gives back a RawImp rather than a checked term,
which allows it to include case expressions
* Case with one pattern is resugared to a destructuring let
* Some name generation issues address in function generation
We look at intermediate results for local variables which are functions
that return a concrete type, or recursive calls that return a single
constructor type. In these cases, we:
* let bind the local variable/recursive call
* generate a new definition for the scope, as a 'case' function
When we recursively generate the definition, it's a bit more restricted
so as not to explode the search space. We only take the first result, we
only look one constructor deep, and we go right to left on variable
splitting so only deconstruct the name we've just added.
