Coq main source components (in link order)
------------------------------------------

clib : Basic files in lib/, such as util.ml
lib : Other files in lib/
kernel
library
pretyping
interp
proofs
printing
parsing
tactics
toplevel

Special components
------------------

intf :

 Contains mli-only interfaces, many of them providing a.s.t.
 used for dialog bewteen coq components. Ex: Constrexpr.constr_expr
 produced by parsing and transformed by interp.

grammar :

 Camlp5 syntax extensions. The file grammar/grammar.cma is used
 to pre-process .ml4 files containing EXTEND constructions,
 either TACTIC EXTEND, ARGUMENTS EXTEND or VERNAC ... EXTEND.
 This grammar.cma incorporates many files from other directories
 (mainly parsing/), plus some specific files in grammar/.
 The other syntax extension grammar/q_constr.cmo is a addition to
 grammar.cma with a constr PATTERN quotation.


Hierarchy of A.S.T.
-------------------

*** Terms ***

             ...          ...
              |            /\
    parsing   |            | printing
              |            |
              V            |
           Constrexpr.constr_expr
              |            /\
 constrintern |            | constrextern
  (in interp) |            | (in interp)
globalization |            |
              V            |
           Glob_term.glob_constr
              |            /\
    pretyping |            | detyping
              |            | (in pretyping)
              V            |
               Term.constr
                 |     /\
   safe_typing   |      |
   (validation   |      |
    by kernel)   |______|


*** Patterns ***

  |
  | parsing
  V
constr_pattern_expr = constr_expr
  |
  | Constrintern.interp_constr_pattern (in interp)
  | reverse way in Constrextern
  V
Pattern.constr_pattern
  |
  ---> used for instance by Matching.matches (in pretyping)


*** Notations ***


Notation_term.notation_constr

Conversion from/to glob_constr in Notation_ops

TODO...


*** Tactics ***

 |
 | parsing
 V
Tacexpr.raw_tactic_expr
 |
 | Tacinterp.intern_pure_tactic (?)
 V
Tacexpr.glob_tactic_expr
 |
 | Tacinterp.eval_tactic (?)
 V
Proof_type.tactic

TODO: check with Hugo


*** Vernac expressions ***

Vernacexpr.vernac_expr, produced by parsing, used in Vernacentries and Vernac