Commit graph

14 commits

Author SHA1 Message Date
Leonardo de Moura
20a36e98ec feat(library/elaborator): modify how elaborator handles constraints of the form ?M << P and P << ?M, where P is a proposition.
Before this commit, the elaborator would only assign ?M <- P, if P was normalized. This is bad since normalization may "destroy" the structure of P.

For example, consider the constraint
[a : Bool; b : Bool; c : Bool] ⊢ ?M::1 ≺ implies a (implies b (and a b))

Before this, ?M::1 will not be assigned to the "implies-term" because the "implies-term" is not normalized yet.
So, the elaborator would continue to process the constraint, and convert it into:

[a : Bool; b : Bool; c : Bool] ⊢ ?M::1 ≺ if Bool a (if Bool b (if Bool (if Bool a (if Bool b false true) true) false true) true) true

Now, ?M::1 is assigned to the term
     if Bool a (if Bool b (if Bool (if Bool a (if Bool b false true) true) false true) true) true

This is bad, since the original structure was lost.

This commit also contains an example that only works after the commit is applied.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-29 09:15:01 -08:00
Leonardo de Moura
5dfb3b8b56 feat(frontends/lean/parse): allow script-code blocks to be used in the apply command
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-28 21:48:30 -08:00
Leonardo de Moura
9c60eed93c refactor(kernel/metavar): avoid using unique names for default metavariable prefix
The problem is that unique names depend on the order compilation units are initialized. The order of initialization is not specified by the C++ standard. Then, different compilers (or even the same compiler) may produce different initialization orders, and consequently the metavariable prefix is going to be different for different builds. This is not a bug, but it makes unit tests to fail since the output produced by different builds is different for the same input file.
Avoiding unique name feature in the default metavariable prefix avoids this problem.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-07 10:16:25 -08:00
Leonardo de Moura
4dd6cead83 refactor(equality): make homogeneous equality the default equality
It was not a good idea to use heterogeneous equality as the default equality in Lean.
It creates the following problems.

- Heterogeneous equality does not propagate constraints in the elaborator.
For example, suppose that l has type (List Int), then the expression
     l = nil
will not propagate the type (List Int) to nil.

- It is easy to write false. For example, suppose x has type Real, and the user
writes x = 0. This is equivalent to false, since 0 has type Nat. The elaborator cannot introduce
the coercion since x = 0 is a type correct expression.

Homogeneous equality does not suffer from the problems above.
We keep heterogeneous equality because it is useful for generating proof terms.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-29 16:20:06 -07:00
Leonardo de Moura
d0009d0242 feat(frontends/lean): make the first argument of if-expression implicit, add support for marking implicit arguments on builtin symbols (aka semantic attachments)
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-29 15:53:50 -07:00
Leonardo de Moura
7c8daf8974 fix(kernel/metavar): make sure the justification and substitution are always matching each other
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-29 02:39:52 -07:00
Leonardo de Moura
2c6d4d2225 fix(kernel/normalizer): do not apply substitutions in the normalizer
It is incorrect to apply substitutions during normalization.
The problem is that we do not have support for tracking justifications in the normalizer. So, substitutions were being silently applied during normalization. Thus, the correctness of the conflict resolution in the elaboration was being affected.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-29 02:14:48 -07:00
Leonardo de Moura
dbefc91151 fix(kernel/metavar): add normalize assignment justification
We need that when we normalize the assignment in a metavariable environment.
That is, we replace metavariable in a substitution with other assignments.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-27 11:02:34 -07:00
Leonardo de Moura
a5c3829d1b feat(kernel): add unexpected_metavar_occurrence exception
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-24 19:56:44 -07:00
Leonardo de Moura
46b9b2114a fix(tests/lean): adjust error messages in the expected output
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-24 19:27:26 -07:00
Leonardo de Moura
99a163f11d Simplify metavariable context. Now, we have only 'lift' and 'inst' instead of 'subst', 'lift' and 'lower'
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-09-16 19:32:28 -07:00
Leonardo de Moura
63e102055e Move metavariables to the kernel. This is the first step for implementing the new elaborator.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-09-15 12:09:01 -07:00
Leonardo de Moura
df116f88e0 Improve pretty printer for Pi's
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-09-08 11:04:07 -07:00
Leonardo de Moura
87d3961158 Improve elaborator error messages
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-09-04 16:36:58 -07:00