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The earlier type [struct_expr_body] was far too broad,
leading to code with unclear invariants, many "assert false", etc etc.
Its replacement [module_alg_expr] has only three constructors:
* MEident
* MEapply : note the module_path as 2nd arg, no more constraints here
* MEwith : no more constant_body inside, constr is just fine
But no more SEBfunctor or SEBstruct constructor here (see below).
This way, this datatype corresponds to algebraic expressions,
i.e. anything that can appear in non-interactive modules.
In fact, it even coincides now with [Entries.module_struct_entry].
- Functor constructors are now necessarily on top of other
structures thanks to a generic [functorize] datatype.
- Structures are now separated from algebraic expressions by design :
the [mod_type] and [typ_expr] fields now only contain structures
(or functorized structures), while [mod_type_alg] and [typ_expr_alg]
are restricted to algebraic expressions only.
- Only the implementation field [mod_expr] could be either algebraic
or structural. We handle this via a specialized datatype
[module_implementation] with four constructors:
* Abstract : no implementation (cf. for instance Declare Module)
* Algebraic(_) : for non-interactive modules, e.g. Module M := N.
* Struct(_) : for interactive module, e.g. Module M : T. ... End M.
* FullStruct : for interactive module with no type restriction.
The [FullStruct] is a particular case of [Struct] where the implementation
need not be stored at all, since it is exactly equal to its expanded
type present in [mod_type]. This is less fragile than hoping as earlier
that pointer equality between [mod_type] and [mod_expr] will be
preserved...
- We clearly emphasize that only [mod_type] and [typ_expr] are
relevant for the kernel, while [mod_type_alg] and [typ_expr_alg]
are there only for a nicer extraction and shorter module printing.
[mod_expr] is also not accessed by the kernel, but it is important
for Print Assumptions later.
- A few implicit invariants remain, for instance "no MEwith in mod_expr",
see the final comment in Declarations
- Heavy refactoring of module-related files : modops, mod_typing,
safe_typing, declaremods, extraction/extract_env.ml ...
- Coqchk has been adapted accordingly. The code concerning MEwith
in Mod_checking is now gone, since we cannot have any in mod_expr.
git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16712 85f007b7-540e-0410-9357-904b9bb8a0f7
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