1. 11 May, 2015 1 commit
  2. 20 Mar, 2015 1 commit
  3. 19 Mar, 2015 1 commit
  4. 07 Nov, 2014 1 commit
  5. 16 Oct, 2014 2 commits
    • Andrei Paskevich's avatar
      Term: revert the two discussion points from the last commit · 8527ea1d
      Andrei Paskevich authored
      - hide the closure variable
      - split t_app_beta into t_func_app_beta, which returns terms,
        and t_pred_app_beta which returns formulas
      
      Also:
      - check for non-recursivity in t_open_lambda
      - implement t_is_lambda via t_open_lambda (less efficient,
        but the correct code without opening would be horrendous)
      - drop t_app_lambda, subsumed by t_[func|pred]_app_beta
      - support nested lambdas in t_[func|pred]_app_beta
      8527ea1d
    • Andrei Paskevich's avatar
      Term: lambda-manipulating functions · 235fac91
      Andrei Paskevich authored
      Two points for discussion:
      
      - t_lambda accepts both terms and formulas for the body.
        Thus, t_open_lambda, t_app_lambda, and t_app_beta can all
        return a term or a formula, depending on what is inside
        the lambda term. The caller should not forget to check.
        We could, in principle, always return a term (bool-typed
        when needed), which would exclude a possible run-time error,
        but then a caller who expects a formula, would have to
        recognize the results of the form [if f then True else False],
        before blindly attaching [== True] to them. Maybe still worth it:
        it's better if a forgotten check leads to an inefficient formula
        than to a type-checking error.
      
      - t_lambda takes a preid which will be the binding variable in the
        produced epsilon. This permits us to give names to our lambdas
        if we want it (what for?) and to give locations to intermediate
        terms inside the epsilon. Overall, it's not very useful and can
        probably be removed.
      235fac91
  6. 20 Aug, 2014 3 commits
  7. 29 Mar, 2014 1 commit
  8. 14 Mar, 2014 1 commit
  9. 03 Dec, 2013 1 commit
  10. 01 Nov, 2013 2 commits
  11. 30 Oct, 2013 1 commit
    • Andrei Paskevich's avatar
      Term: do not h-cons patterns and terms, t_equal becomes t_equal_alpha · 004f0edf
      Andrei Paskevich authored
      The rationale for this change is that the major case of term duplication
      is a transformation that changes only some parts of a term, leaving the
      rest intact. This case can be handled with the help of Term.t_label_copy
      (which must be called anyway, to preserve labels): if the two terms are
      "similar", i.e. composed from the identical components, we return the
      original and drop the copy. The duplication of unrelated terms is more
      rare, because of bound variables which are mostly unique.
      
      Decls and tasks are still h-consed, however, to permit memoization.
      
      On the same example of BWare the gain is quite visible:
      
      why3-replayer : hcons
      
      242.96user 12.04system 4:16.31elapsed 99%CPU (0avgtext+0avgdata 2007184maxresident)k
      
      why3-replayer : no hcons
      
      106.81user 7.86system 1:59.32elapsed 96%CPU (0avgtext+0avgdata 1656908maxresident)k
      004f0edf
  12. 29 Oct, 2013 1 commit
    • Andrei Paskevich's avatar
      Term: do not store t_vars in terms · 7abeba05
      Andrei Paskevich authored
      we still keep bv_vars in the binders, so calculating the set
      of free variables only has to descend to the topmost binders.
      The difference on an example from BWare is quite striking:
      
      /usr/bin/time why3-replayer : with t_vars
      
      505.14user 15.58system 8:40.45elapsed 100%CPU (0avgtext+0avgdata 3140336maxresident)k
      
      /usr/bin/time why3-replayer : without t_vars
      
      242.96user 12.04system 4:16.31elapsed 99%CPU (0avgtext+0avgdata 2007184maxresident)k
      
      Not only we take 2/3 of memory, but we also gain in speed (less work
      for the GC, most probably).
      
      This patch should be tested on big WhyML examples,
      since src/whyml/mlw_*.ml are big users of t_vars.
      
      Thanks to Guillaume for the suggestion.
      7abeba05
  13. 21 Oct, 2013 1 commit
  14. 19 Oct, 2013 1 commit
    • Andrei Paskevich's avatar
      switch Typing to the new Dterm-based API · 460e93f8
      Andrei Paskevich authored
      Also:
      
      - Make [Highord.pred 'a] an alias for [Highord.func 'a bool],
      rename [Highorg.(@!)] to [(@)], remove [Highorg.(@?)], remove
      the quantifiers [\!] and [\?] and only leave [\] which is the
      only true lambda now;
      
      - Allow mixing bool and Prop in logic, Dterm will introduce
      coercions where necessary (trying to minimize the number of
      if-then-else in the term context).
      460e93f8
  15. 26 Aug, 2013 1 commit
  16. 22 Aug, 2013 1 commit
  17. 20 Aug, 2013 1 commit
  18. 17 Apr, 2013 1 commit
  19. 06 Mar, 2013 1 commit
  20. 04 Mar, 2013 1 commit
    • Andrei Paskevich's avatar
      whyml: match expression is ghost if we look inside ghost fields · 43b684d0
      Andrei Paskevich authored
      We store in every lsymbol a new integer field ls_constr,
      equal to zero if the lsymbol is not a constructor, and equal
      to the number of constructors of the lsymbol's type otherwise.
      It is allowed to declare or define an lsymbol with ls_constr > 0
      as an ordinary function (otherwise algebraic type elimination
      wouldn't work - though we might still check this in theories),
      but it is forbidden to use a wrong ls_constr in algebraic type
      definitions.
      
      The ghostness of a match expression is now determined as follows:
      
      If at least one branch expression is ghost,
        then the match is ghost;
      else if there is only one branch,
        then the match is not ghost;
      else if the matched expression is ghost,
        then the match is ghost;
      else if at least one pattern matches a ghost field
              against a constructor with ls_constr > 1
        then the match is ghost;
      else
        the match is not ghost.
      
      We do just enough to recognize obvious non-ghost cases, and
      make no attempt to handle redundant matches or to detect
      exhaustive or-patterns in subpatterns.
      43b684d0
  21. 03 Mar, 2013 1 commit
    • Andrei Paskevich's avatar
      track dangerous applications of equality · bb6734a1
      Andrei Paskevich authored
      In programs, but also in pure theories, it is not safe to compare
      arbitrary types. For example, if we have a record with ghost fields,
      a comparison may produce different results before and after ghost
      code elimination. Even for pure types like 'map' or 'set', it is
      unlikely that the result of logical equality will be the same as
      the result of OCaml structural equality on the implemented type.
      
      This commit makes the first step towards fixing this issue.
      We proceed in the following way:
      
      1. Every lsymbol (pure function or predicate symbol) carries
         a subset of type variables of its signature, called "opaque
         type variables". By marking a type variable 'a opaque in an
         lsymbol's signature, the user guarantees that this lsymbol
         can be implemented without ever comparing values of type 'a.
         In other words, this is a promise not to break into a type
         variable.
      
         The corresponding syntax is: "predicate safe (x y : ~'a)".
      
         All type variables in undefined symbols are non-opaque,
         unless annotated otherwise. Non-opaque is the default
         to keep the change conservative.
      
         Opacity of type variables in defined symbols is inferred
         from the definition. If the definition violates a given
         opacity annotation, an exception is raised. Notice that
         we only check definitions in _theory_ declarations. One
         can define an lsymbol in a _task_ in a way that violates
         opacity. We cannot forbid it, because various elimination
         transformations would replace safe operations (such as
         matching) with equalities. This is not a problem, since in
         the pure logical realm of provers opacity is not required
         One exception would be Coq, whose transformation chain must
         never perform such operations.
      
         All type variables in inductive predicates are non-opaque.
         Indeed, we can redefine equality via an inductive predicate.
         [TODO: find safe forms of inductive definitions and implement
         more reasonable restrictions.]
      
         All type variables in constructors and field symbols are opaque.
      
         It is forbidden to instantiate an opacity-preserving symbol
         with an opacity-breaking one in a clone substitution.
      
      2. Similar type variable tracking is implemented for program symbols.
         Type variables in the signature of a "val" are non-opaque unless
         annotated otherwise. Opacity of type variables in defined symbols
         is inferred from the definition, and an exception is raised, if
         a given annotation is violated.
      
         The internal mechanism of tracking is different: the "eff_compar"
         field in effects contains the type variables that occur under
         equality or any other opacity-breaking operation. In this respect,
         our API is inconsistent between lsymbols and psymbols: the former
         asks for the opaque tvsymbols, the latter requires us to fill the
         spec with "comparison effects" for the non-opaque ones. [TODO:
         add the "~opaque" argument to create_psymbol and make the WhyML
         core fill the effect under the hood.]
      
         Every time an lsymbol or a psymbol is applied in a program,
         we check the substitution into its signature's type variables.
         If a non-opaque type variable is instantiated with a program type,
         an exception is raised. [TODO: be more precise and reject only
         types with ghost and model components - being mutable, private,
         or carrying an invariant doesn't conflict with equality.]
      
         Notice that we do not allow to compare program types even in
         the ghost code. This is not needed if we only consider the
         problems of the code extraction, but _might_ be necessary,
         if we also want to protect Coq realisations (see below).
      
      This commit fixes the immediate problem of breaking the ghost
      guarantees when equality or some other opacity-breaking lsymbol
      is applied in a program to a type with ghost or "model" parts.
      
      This leaves the problem of code extraction for programs that
      compare complex types such as maps or sets (Coq driver is
      affected by this, too, I guess). The next step is to provide
      annotations for problematic type constructors. A declaration
      "type ~map 'a 'b" would mean "logical equality on this type
      is likely to be different from the structural equality on any
      implementation of this type - therefore do not apply equality
      to it: neither in programs (because this can't be implemented),
      nor in pure functions (because they are extracted, too, and
      because this can't be realized with Leibniz equality in Coq)."
      [TODO: discuss and implement.]
      
      [TODO: mb choose better term for "opaque" and notation for ~'a.]
      bb6734a1
  22. 21 Jan, 2013 1 commit
  23. 06 Nov, 2012 1 commit
  24. 05 Nov, 2012 1 commit
  25. 04 Nov, 2012 2 commits
  26. 21 Oct, 2012 2 commits
  27. 20 Oct, 2012 1 commit
    • Andrei Paskevich's avatar
      simplify copyright headers · 11598d2b
      Andrei Paskevich authored
      + create AUTHORS file
      + fix the linking exception in LICENSE
      + update the "About" in IDE
      + remove the trailing whitespace
      + inflate my scores at Ohloh
      11598d2b
  28. 18 Jul, 2012 1 commit
  29. 17 Jun, 2012 1 commit
  30. 06 May, 2012 1 commit
  31. 09 Apr, 2012 1 commit
  32. 18 Mar, 2012 1 commit
  33. 14 Feb, 2012 1 commit
  34. 08 Feb, 2012 1 commit