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32 commits

Author SHA1 Message Date
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
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
2434024272 fix(library/rewriter): warning in release mode
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-17 15:46:49 -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
14c6218bdc chore(kernel): file name convention
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 20:06:29 -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
ecc5d1bc3a refactor(kernel): move printer to library, cleanup io_state interface
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 13:37:50 -08:00
Leonardo de Moura
49698bd053 chore(library/all): remove unnecessary files
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 13:37:25 -08:00
Leonardo de Moura
ecd62a1783 refactor(builtin/basic): rename basic.lean to kernel.lean
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:46:03 -08:00
Leonardo de Moura
4229e498d2 refactor(kernel/type_checker): combine type_checker and type_inferer into a single class, and avoid code duplication
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-22 11:51:38 -08:00
Leonardo de Moura
2e5e5e187f chore(util/rc): remove unnecessary argument from LEAN_COPY_REF and LEAN_MOVE_REF macros
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-13 15:01:24 -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
bcc8b67592 chore(*): consistent file name convention
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-03 12:40:52 -08:00
Soonho Kong
a2d6918348 fix(library/rewriter): use Abst axiom in lambda_body RW 2013-12-01 22:24:12 -05:00
Soonho Kong
064e3fe20d refactor(library/rewriter): rename lc => ti 2013-12-01 01:59:20 -05:00
Soonho Kong
506cca0ac1 feat(library/rewriter): implement depth RW 2013-12-01 01:59:20 -05:00
Soonho Kong
ae0508128f refactor(library/rewriter): move apply_rewriter_fn into rewriter.h 2013-12-01 00:57:09 -05:00
Soonho Kong
d7ba5e3893 doc(library/rewriter): add doxygen annotations for rewrite_* funcs 2013-12-01 00:47:53 -05:00
Soonho Kong
f205dd0763 fix(library/rewriter): unused variable warnings 2013-11-30 07:05:18 -05:00
Soonho Kong
f5f7380fbe feat(library/rewriter): add apply_rewriter_fn which will be used in depth RW 2013-11-30 02:25:30 -05:00
Soonho Kong
1d76a6f71d feat(library/rewriter): add rewrite_* functions
rewrite_* functions take the rewriting results of the sub-components and
construct the rewriting result for the main component.

For instance, rewrite_app function takes env, ctx, and the value v s.t.

v = (e_0 e_1 ... e_n)

and the rewriting results for e_i's as a vector(buffer)

(e'_0, pf_0 -- proof of e_0 = e'_0)
(e'_1, pf_1 -- proof of e_1 = e'_1)
...
(e'_n, pf_n -- proof of e_n = e'_n).

Then rewrite_app function construct the new v'

v' = (e'_0 e'_1 ... e'_n)

and the proof of v = v' which is constructed with pf_i's.

These functions are used in the component rewriters such as app_RW and
let_type_RW, as well as more complicated rewriters such as depth
rewriter.
2013-11-30 02:25:29 -05:00
Leonardo de Moura
d87ad9eb7e refactor(util/lua): propagate C++ Lean exceptions in Lua
The following call sequence is possible:
C++ -> Lua -> C++ -> Lua -> C++

The first block of C++ is the Lean main function.
The main function invokes the Lua interpreter.
The Lua interpreter invokes a C++ Lean API.
Then the Lean API invokes a callback implemented in Lua.
The Lua callback invokes another Lean API.
Now, suppose the Lean API throws an exception.
We want the C++ exception to propagate over the mixed C++/Lua call stack.
We use the clone/rethrow exception idiom to achieve this goal.

Before this commit, the C++ exceptions were converted into strings
using the method what(), and then they were propagated over the Lua
stack using lua_error. A lua_error was then converted into a lua_exception when going back to C++.
This solution was very unsatisfactory, since all C++ exceptions were being converted into a lua_exception, and consequently the structure of the exception was being lost.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-27 12:25:29 -08:00
Leonardo de Moura
7f96c07a01 refactor(library): rename light_checker to type_inferer
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-22 08:15:36 -07:00
Leonardo de Moura
d843d432d3 refactor(kernel): move printer and formatter objects to the kernel
The printer and formatter objects are not trusted code.
We moved them to the kernel to be able to provide them as an argument to the trace objects.
Another motivation is to eliminate the kernel_exception_formatter hack.
With the formatter in the kernel, we can implement the pretty printer for kernel exceptions as a virtual method.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-10-22 08:15:36 -07:00
Soonho Kong
3381df0150 fix(util/list_fn): rename iter to for_each 2013-10-01 09:03:07 -07:00
Soonho Kong
7c0b56ad0d feat(library/rewriter): implement repeat/app/lambda/pi/try rewriter
- refactor to use rewriter_cell
 - implement display and operator<< for debugging
2013-10-01 00:30:31 -07:00
Soonho Kong
e6c76fbe76 refactor(library/rewriter/fo_match): add more lean_trace for debugging 2013-10-01 00:20:12 -07:00
Soonho Kong
285495313b refactor(rewrite): use scoped_map as a type of substitution 2013-09-27 01:45:22 -07:00
Soonho Kong
1d4a1b68f5 refactor(fo_match): use scoped_map 2013-09-27 01:44:05 -07:00
Leonardo de Moura
6477708d78 refactor(debug): improve lean_unreachable(), now we can avoid 'fake' return statements
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-09-25 21:27:20 -07:00
Soonho Kong
1d8b7dc193 Update 'orelse' and 'then' rewriter to take a list of rewriters 2013-09-25 16:46:39 -07:00
Soonho Kong
a50f5f92b8 Rename 'rewrite' to 'Rewriter', change type of rewriter::operator() 2013-09-25 15:38:16 -07:00