@digama0 After this commit, your example will also produce a
non-destructive update.
```lean
structure test :=
(data1 : array nat 3)
(data2 : array nat 3)
(sz: nat)
def test.write (s : test) (i : fin 3) (v : nat) :=
{s with data1 := s^.data1^.write i v, data2 := s^.data2^.write i v}
set_option trace.array.update true
(fin.of_nat 1) 10 in
(a^.data1^.read (fin.of_nat 1), a^.data2^.read (fin.of_nat 2)) -- destructive write
```
This is just overhead for begin...end blocks.
Moreover, "live variable analysis" is currently a recursive
procedure, and Lean will run of stack space when processing big begin
end blocks (> 1000 tactics).
Suppose we have
def foo : some_proposition :=
by non_trivial_automation
Moreover, assume non_trivial_automation generates a huge proof.
Since this definition is marked with `def`, it is sent to the VM
compiler. In this kind of scenario, the compiler preprocessor was
spending a long time applying "useless" preprocessing steps.
We say they are useless because in the end everything is erased.
I think we should make sure every definition has some bytecode
associated with it in the VM even if the type of the definition
is a proposition. In this way, we have a simple invariant:
every definition has a vm_decl associated with it.
So, we workaround the performance problem above by short-circuiting
the preprocessor for propositions.
Fixes#1363
After error recovery has been implemented in the elaborator, a few
assumptions made in the type context are not valid anymore since we may
be recovering from errors, and the local and metavariable contexts may
be invalid.
I used the approach used in the class environment.
- find* methods return optional<...>
- get* methods throw exception for unknown elements
Remarks:
I preserved code patterns such as
optional<local_decl> d = lctx.find_local_decl(...)
lean_assert(d)
and did not convert them into
local_decl d = lctx.get_local_decl(...)
Reason: the intention is clear that the local must be defined there.
If it is not we should analyze the problem and decide whether we should
throw an exception or not.
However, I converted code patterns such as
local_decl d = *lctx.find_local_decl(...)
into
local_decl d = lctx.get_local_decl(...)
Disclaimer: this change fixes issue #1363, but it may obfuscate other bugs.
(Type u) is the old (Type (u+1))
(PType u) is the old (Type u)
Type* is the old (Type (_+1))
PType* is the old Type*
The stdlib can be compiled, but we still have > 70 broken tests
See discussion at #1341
