Commit graph

24 commits

Author SHA1 Message Date
Leonardo de Moura
fddcdb8f40 fix(library/elaborator): bug in process_lower
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-21 04:13:14 -08:00
Leonardo de Moura
ce84fe5d33 feat(frontends/lean): improve error messages when elaborator cannot instantiate all metavariables
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-20 22:00:50 -08:00
Leonardo de Moura
812c1a2960 feat(library/elaborator): only expand definitions that are not marked as hidden
The elaborator produces better proof terms. This is particularly important when we have to prove the remaining holes using tactics.
For example, in one of the tests, the elaborator was producing the sub-expression

 (λ x : N, if ((λ x::1 : N, if (P a x x::1) ⊥ ⊤) == (λ x : N, ⊤)) ⊥ ⊤)

After, this commit it produces

 (λ x : N, ¬ ∀ x::1 : N, ¬ P a x x::1)

The expressions above are definitionally equal, but the second is easier to work with.

Question: do we really need hidden definitions?
Perhaps, we can use only the opaque flag.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-20 02:16:49 -08:00
Leonardo de Moura
f43db96e1f fix(frontends/lean/pp): pretty printer for Type
Add parenthesis around Type when it has a universe.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-19 15:24:45 -08:00
Leonardo de Moura
46627289b8 fix(kernel/expr): avoid '_' as a binder name, we use '_' as a placeholder in the Lean frontend
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-19 14:47:53 -08:00
Leonardo de Moura
993bea8206 refactor(library/elaborator): improve elaborator state data-structure
The "quota" hack used before this commit was inefficient, and too hackish.
This commit uses two lists of constraints: active and delayed.
The delayed constraints are only processed when there are no active constraints.
We use a simple index to quickly find which delayed constraints have assigned metavariables.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

checkpoint

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-14 23:27:08 -08:00
Leonardo de Moura
3d30664611 feat(kernel/type_checker): provide the metavar_env to instantiate, it will minimize the number of local_entries needed
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-14 15:13:56 -08:00
Leonardo de Moura
4357c9196e feat(kernel/metavar): make sure that a metavariable 'm' can only be assigned to a term that contains free variables available in the context associated with 'm'
This commit also simplifies the method check_pi in the type_checker and type_inferer.
It also fixes process_meta_app in the elaborator.
The problem was in the method process_meta_app and process_meta_inst.
They were processing convertability constrains as equality constraints.
For example, process_meta_app would handle

    ctx |- Type << ?f b

as

    ctx |- Type =:= ?f b

This is not correct because a ?f that returns (Type U) for b satisfies the first but not the second.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-14 12:25:00 -08:00
Leonardo de Moura
fa03ae2a26 fix(library/elaborator): strength elaborator procedure for handling equality and convertability constraints
This commit improves the condition for showing that an equality(and convertability) constraint cannot be solved. A nice consequence is that Lean produces nicer error messages. For example, the error message for unit test elab1.lean is more informative.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-06 13:04:34 -08:00
Leonardo de Moura
e3848d43a2 feat(frontends/lean): improve tactic command parsing in interactive mode
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-05 16:28:08 -08:00
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