Commit graph

23 commits

Author SHA1 Message Date
Leonardo de Moura
603dafbaf7 refactor(kernel): remove 'let'-expressions
We simulate it in the following way:
1- An opaque 'let'-expressions (let x : t := v in b) is encoded as
      ((fun (x : t), b) v)
   We also use a macro (let-macro) to mark this pattern.
   Thus, the pretty-printer knows how to display it correctly.

2- Transparent 'let'-expressions are eagerly expanded by the parser.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-06-24 16:27:27 -07:00
Leonardo de Moura
5ce134e24e chore(kernel): binder => binding where appropriate
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-05-17 11:37:27 -07:00
Leonardo de Moura
40b3129e7b refactor(kernel): improve names
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-05-16 11:28:05 -07:00
Leonardo de Moura
9c5dfc387b refactor(kernel/replace_visitor): remove context from replace_visitor
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-05-14 15:53:09 -07:00
Leonardo de Moura
4842ae4fc7 refactor(kernel): store macro arguments in the macro_expr
Before this commit, we "stored" macro arguments using applications.
This representation had some issues. Suppose we use [m a] to denote a macro
application. In the old representation, ([m a] b) and [m a b] would have
the same representation. Another problem is that some procedures (e.g., type inference)
would not have a clean implementation.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-04-25 15:02:56 -07:00
Leonardo de Moura
bc8379256a refactor(kernel): remove pairs from kernel
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-04-17 10:52:07 -07:00
Leonardo de Moura
eb046c11fb refactor(kernel): the type in let-exprs is not optional anymore, if the user does not provide it, we use a metavariable
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-03-18 10:27:55 -07:00
Leonardo de Moura
16aa1ebbac refactor(kernel): replace_visitor
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-03-18 10:27:55 -07:00
Leonardo de Moura
1ec01f5757 refactor(builtin): merge pair.lean with kernel.lean, and add basic theorems
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-02-07 16:04:44 -08:00
Leonardo de Moura
6d7ec9d7b6 refactor(kernel): add heterogeneous equality back to expr
The main motivation is that we will be able to move equalities between universes.

For example, suppose we have
    A : (Type i)
    B : (Type i)
    H : @eq (Type j) A B
where j > i

We didn't find any trick for deducing (@eq (Type i) A B) from H.
Before this commit, heterogeneous equality as a constant with type

   heq : {A B : (Type U)} : A -> B -> Bool

So, from H, we would only be able to deduce

   (@heq (Type j) (Type j) A B)

Not being able to move the equality back to a smaller universe is
problematic in several cases. I list some instances in the end of the commit message.

With this commit, Heterogeneous equality is a special kind of expression.
It is not a constant anymore. From H, we can deduce

   H1 : A == B

That is, we are essentially "erasing" the universes when we move to heterogeneous equality.
Now, since A and B have (Type i), we can deduce (@eq (Type i) A B) from H1. The proof term is

  (to_eq (Type i) A B (to_heq (Type j) A B H))  :  (@eq (Type i) A B)

So, it remains to explain why we need this feature.

For example, suppose we want to state the Pi extensionality axiom.

axiom hpiext {A A' : (Type U)} {B : A → (Type U)} {B' : A' → (Type U)} :
      A = A' → (∀ x x', x == x' → B x == B' x') → (∀ x, B x) == (∀ x, B' x)

This axiom produces an "inflated" equality at (Type U) when we treat heterogeneous
equality as a constant. The conclusion

     (∀ x, B x) == (∀ x, B' x)

is syntax sugar for

   (@heq (Type U) (Type U) (∀ x : A, B x) (∀ x : A', B' x))

Even if A, A', B, B' live in a much smaller universe.

As I described above, it doesn't seem to be a way to move this equality back to a smaller universe.

So, if we wanted to keep the heterogeneous equality as a constant, it seems we would
have to support axiom schemas. That is, hpiext would be parametrized by the universes where
A, A', B and B'. Another possibility would be to have universe polymorphism like Agda.
None of the solutions seem attractive.

So, we decided to have heterogeneous equality as a special kind of expression.
And use the trick above to move equalities back to the right universe.

BTW, the parser is not creating the new heterogeneous equalities yet.
Moreover, kernel.lean still contains a constant name heq2 that is the heterogeneous
equality as a constant.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-02-07 10:28:10 -08:00
Leonardo de Moura
5e5ab1429d feat(frontends/lean): parse and pretty print sigma types
This commit also fixes some bugs in the implementation of Sigma types.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-02-03 18:16:00 -08:00
Leonardo de Moura
8eec289ce1 feat(kernel): add dependent pairs
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-02-03 16:52:49 -08:00
Leonardo de Moura
a43020b31b refactor(kernel): remove heterogeneous equality
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-16 17:39:12 -08:00
Leonardo de Moura
411f14415d feat(builtin): automatically generate Lean/C++ interface for builtin theories
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-09 18:09:53 -08:00
Leonardo de Moura
af42078205 fix(kernel): incorrect use of scoped_map
This commit also adds a new test that exposes the problem.
The scoped_map should not be used for caching values in the normalizer and type_checker. When we extend the context, the meaning of all variables is modified (we are essentially performing a lift). So, the values stored in the cache are not correct in the new context.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-16 15:11:39 -08:00
Leonardo de Moura
2f88d6710c feat(kernel/expr): add some_expr and none_expr for building values of type optional<expr>
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-08 10:34:38 -08:00
Leonardo de Moura
3e1fd06903 refactor(kernel/expr): remove 'null' expression, and operator bool for expression
After this commit, a value of type 'expr' cannot be a reference to nullptr.
This commit also fixes several bugs due to the use of 'null' expressions.

TODO: do the same for kernel objects, sexprs, etc.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-07 23:21:10 -08:00
Leonardo de Moura
b6b520302d feat(kernel/replace_visitor): relax replace_visitor contract, the input expression can be null
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-07 15:35:26 -08:00
Leonardo de Moura
e2999d3ff6 feat(*): add component name to check_stack and check_system
I also reduced the stack size to 8 Mb in the tests at tests/lean and tests/lean/slow. The idea is to simulate stackoverflow conditions.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-07 15:11:55 -08:00
Leonardo de Moura
873a07d34c feat(kernel/replace_visitor): check interrupted flag and stackoverflow
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-05 05:42:12 -08:00
Leonardo de Moura
7f088b7635 feat(kernel): add (optional) field m_type to expr_const, this field is useful for implementing the tactic framework
This field should not be visible in the external API.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-19 11:21:52 -08:00
Soonho Kong
044813615e fix: add '#include <tuple>' 2013-11-03 13:00:42 -05:00
Leonardo de Moura
c1e451151a feat(replace_visitor): add an abstract class for applying transformations on expressions
I also removed replace_using_ctx since it is subsumed by the new class.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-23 15:01:37 -07:00