path: root/kernel/term.mli

(* $Id$ *)

(*i*)
open Pp
open Names
open Generic
(*i*)

(*s The operators of the Calculus of Inductive Constructions. 
  ['a] is the type of sorts. ([XTRA] is an extra slot, for putting in 
  whatever sort of operator we need for whatever sort of application.) *)

type existential_key = int

type 'a oper = 
  | Meta of int
  | Sort of 'a
  | Cast | Prod | Lambda
  | AppL | Const of section_path | Abst of section_path
  | Evar of existential_key
  | MutInd of inductive_path
  | MutConstruct of constructor_path
  | MutCase of case_info
  | Fix of int array * int
  | CoFix of int
  | XTRA of string

and case_info = inductive_path option

(*s The sorts of CCI. *)

type contents = Pos | Null

val str_of_contents : contents -> string
val contents_of_str : string -> contents

type sorts =
  | Prop of contents       (* Prop and Set *)
  | Type of Univ.universe  (* Type *)

val mk_Set  : sorts
val mk_Prop : sorts

val print_sort : sorts -> std_ppcmds

(*s The type [constr] of the terms of CCI
  is obtained by instanciating the generic terms (type [term], 
  see \refsec{generic_terms}) on the above operators, themselves instanciated
  on the above sorts. *)

type constr = sorts oper term

type 'a judge = { body : constr; typ : 'a }

type typed_type = sorts judge
type typed_term = typed_type judge

val make_typed : constr -> sorts -> typed_type

val typed_app : (constr -> constr) -> typed_type -> typed_type

val body_of_type : typed_type -> constr
val level_of_type : typed_type -> sorts

val incast_type : typed_type -> constr

val outcast_type : constr -> typed_type

(*s Functions for dealing with constr terms.
  The following functions are intended to simplify and to uniform the 
  manipulation of terms. Some of these functions may be overlapped with
  previous ones. *)

(*  Concrete type for making pattern-matching. *)

type kindOfTerm =
  | IsRel          of int
  | IsMeta         of int
  | IsVar          of identifier
  | IsXtra         of string
  | IsSort         of sorts
  | IsCast         of constr * constr
  | IsProd         of name * constr * constr
  | IsLambda       of name * constr * constr
  | IsAppL         of constr * constr list
  | IsConst        of section_path * constr array
  | IsAbst         of section_path * constr array
  | IsEvar         of int * constr array
  | IsMutInd       of section_path * int * constr array
  | IsMutConstruct of section_path * int * int * constr array
  | IsMutCase      of case_info * constr * constr * constr array
  | IsFix          of int array * int * constr array * name list * constr array
  | IsCoFix        of int * constr array * name list * constr array

(* Discriminates which kind of term is it.  
  Note that there is no cases for [DLAM] and [DLAMV].  These terms do not
  make sense alone, but they must be preceeded by the application of
  an operator. *)

val kind_of_term : constr -> kindOfTerm


(*s Term constructors. *)

(* Constructs a DeBrujin index *)
val mkRel : int -> constr

(* Constructs an existential variable named "?" *)
val mkExistential : constr

(* Constructs an existential variable named "?n" *)
val mkMeta : int -> constr

(* Constructs a Variable *)
val mkVar : identifier -> constr

(* Construct an  [XTRA] term. *)
val mkXtra : string -> constr

(* Construct a type *)
val mkSort : sorts -> constr
val mkProp : constr
val mkSet : constr 
val mkType : Univ.universe -> constr
val prop : sorts
val spec : sorts
val types : sorts 
val type_0 : sorts
val type_1 : sorts

(* Construct an implicit (see implicit arguments in the RefMan).
   Used for extraction *)
val mkImplicit : constr
val implicit_sort : sorts

(* Constructs the term $t_1::t2$, i.e. the term $t_1$ casted with the 
   type $t_2$ (that means t2 is declared as the type of t1). *)
val mkCast : constr -> constr -> constr

(* Constructs the product $(x:t_1)t_2$. $x$ may be anonymous. *)
val mkProd : name -> constr -> constr -> constr

(* non-dependant product $t_1 \rightarrow t_2$ *)
val mkArrow : constr -> constr -> constr

(* named product *)
val mkNamedProd : identifier -> constr -> constr -> constr

(* Constructs the abstraction $[x:t_1]t_2$ *)
val mkLambda : name -> constr -> constr -> constr
val mkNamedLambda : identifier -> constr -> constr -> constr

(* If $a = [| t_1; \dots; t_n |]$, constructs the application 
   $(t_1~\dots~t_n)$. *)
val mkAppL : constr array -> constr
val mkAppList : constr -> constr list  -> constr

(* Constructs a constant *) 
(* The array of terms correspond to the variables introduced in the section *)
val mkConst : section_path -> constr array -> constr

(* Constructs an existential variable *)
val mkEvar : int -> constr array -> constr

(* Constructs an abstract object *)
val mkAbst : section_path -> constr array -> constr

(* Constructs the ith (co)inductive type of the block named sp *)
(* The array of terms correspond to the variables introduced in the section *)
val mkMutInd : section_path -> int -> constr array -> constr

(* Constructs the jth constructor of the ith (co)inductive type of the 
   block named sp. The array of terms correspond to the variables
   introduced in the section *)
val mkMutConstruct : section_path -> int -> int -> constr array -> constr

(* Constructs the term <p>Case c of c1 | c2 .. | cn end *)
val mkMutCase : case_info -> constr -> constr -> constr list -> constr
val mkMutCaseA : case_info -> constr -> constr -> constr array -> constr

(* If [recindxs = [|i1,...in|]]
      [typarray = [|t1,...tn|]]
      [funnames = [f1,.....fn]]
      [bodies   = [b1,.....bn]]
   then [ mkFix recindxs i typarray funnames bodies]
   constructs the $i$th function of the block  

    [Fixpoint f1 [ctx1] = b1
     with     f2 [ctx2] = b2
     ...
     with     fn [ctxn] = bn.]

   \noindent where the lenght of the $j$th context is $ij$.
*)
val mkFix : int array -> int -> typed_type array -> name list 
  -> constr array -> constr

(* Similarly, but we assume the body already constructed *)
val mkFixDlam : int array -> int -> typed_type array
  -> constr array -> constr 

(* If [typarray = [|t1,...tn|]]
      [funnames = [f1,.....fn]]
      [bodies   = [b1,.....bn]] \par\noindent
   then [mkCoFix i typsarray funnames bodies]
   constructs the ith function of the block  
   
    [CoFixpoint f1 = b1
     with       f2 = b2
     ...
     with       fn = bn.]
 *)
val mkCoFix : int -> typed_type array -> name list 
  -> constr array -> constr

(* Similarly, but we assume the body already constructed *)
val mkCoFixDlam : int -> typed_type array -> constr array -> constr


(*s Term destructors. 
   Destructor operations are partial functions and
   raise [invalid_arg "dest*"] if the term has not the expected form. *)

(* Destructs a DeBrujin index *)
val destRel : constr -> int

(* Destructs an existential variable *)
val destMeta : constr -> int
val isMETA : constr -> bool

(* Destructs a variable *)
val destVar : constr -> identifier

(* Destructs an XTRA *)
val destXtra : constr -> string

(* Destructs a sort. [is_Prop] recognizes the sort \textsf{Prop}, whether 
   [isprop] recognizes both \textsf{Prop} and \textsf{Set}. *)
val destSort : constr -> sorts
val contents_of_kind : constr -> contents
val is_Prop : constr -> bool
val is_Set : constr -> bool
val isprop : constr -> bool
val is_Type : constr -> bool
val iskind : constr -> bool

val is_existential_oper : sorts oper -> bool

val isType : sorts -> bool
val is_small : sorts -> bool (* true for \textsf{Prop} and \textsf{Set} *)

(* Destructs a casted term *)
val destCast : constr -> constr * constr
val cast_type : constr -> constr (* 2nd proj *)
val cast_term : constr -> constr (* 1st proj *)
val isCast : constr -> bool

(* Removes recursively the casts around a term i.e.
   [strip_outer_cast] (Cast (Cast ... (Cast c, t) ... ))] is [c]. *)
val strip_outer_cast : constr -> constr

(* Special function, which keep the key casts under Fix and MutCase. *)
val strip_all_casts : constr -> constr

(* Destructs the product $(x:t_1)t_2$ *)
val destProd : constr -> name * constr * constr
val hd_of_prod : constr -> constr
val hd_is_constructor : constr -> bool

(* Destructs the abstraction $[x:t_1]t_2$ *)
val destLambda : constr -> name * constr * constr

(* Destructs an application *)
val destAppL : constr -> constr array
val isAppL : constr -> bool
val hd_app : constr -> constr 
val args_app : constr -> constr array

(* Destructs a constant *)
val destConst : constr -> section_path * constr array
val path_of_const : constr -> section_path
val args_of_const : constr -> constr array

(* Destructs an existential variable *)
val destEvar : constr -> int * constr array

(* Destrucy an abstract term *)
val destAbst : constr -> section_path * constr array
val path_of_abst : constr -> section_path
val args_of_abst : constr -> constr array

(* Destructs a (co)inductive type *)
val destMutInd : constr -> section_path * int * constr array
val op_of_mind : constr -> inductive_path
val args_of_mind : constr -> constr array
val ci_of_mind : constr -> case_info

(* Destructs a constructor *)
val destMutConstruct : constr -> section_path * int * int * constr array
val op_of_mconstr : constr -> constructor_path
val args_of_mconstr : constr -> constr array

(* Destructs a term <p>Case c of lc1 | lc2 .. | lcn end *)
val destCase : constr -> case_info * constr * constr * constr array

(* Destructs the $i$th function of the block  
   $\mathit{Fixpoint} ~ f_1 ~ [ctx_1] = b_1
    \mathit{with}     ~ f_2 ~ [ctx_2] = b_2
    \dots
    \mathit{with}     ~ f_n ~ [ctx_n] = b_n$,
   where the lenght of the $j$th context is $ij$.
*)
val destGralFix : 
  constr array -> constr array * Names.name list * constr array
val destFix : constr -> 
  int array * int * typed_type array * Names.name list * constr array

val destCoFix : 
  constr -> int * typed_type array * Names.name list * constr array

(* Provisoire, le temps de maitriser les cast *)
val destUntypedFix : 
  constr -> int array * int * constr array * Names.name list * constr array
val destUntypedCoFix : 
  constr -> int * constr array * Names.name list * constr array


(*s Other term constructors. *)

val abs_implicit : constr -> constr
val lambda_implicit : constr -> constr
val lambda_implicit_lift : int -> constr -> constr

val applist : constr * constr list -> constr
val applistc : constr -> constr list -> constr
val appvect : constr * constr array -> constr
val appvectc : constr -> constr array -> constr

(* [prodn n l b] = $(x_1:T_1)..(x_n:T_n)b$ 
   where $l = [(x_1,T_1);\dots;(x_n,T_n);Gamma]$ *)
val prodn : int -> (name * constr) list -> constr -> constr

(* [lamn n l b] = $[x_1:T_1]..[x_n:T_n]b$
   where $l = [(x_1,T_1);\dots;(x_n,T_n);Gamma]$ *)
val lamn : int -> (name * constr) list -> constr -> constr

(* [prod_it b l] = $(x_1:T_1)..(x_n:T_n)b$ 
   where $l = [x_1:T_1;..x_n:T_n]$ *)
val prod_it : constr -> (name * constr) list -> constr

(* [lam_it b l] = $[x_1:T_1]..[x_n:T_n]b$ 
   where $l = [x_1:T_1;..;x_n:T_n]$ *)
val lam_it : constr -> (name * constr) list -> constr

(* [to_lambda n l] 
   = $[x_1:T_1]...[x_n:T_n](x_{n+1}:T_{n+1})...(x_{n+j}:T_{n+j})T$
   where $l = (x_1:T_1)...(x_n:T_n)(x_{n+1}:T_{n+1})...(x_{n+j}:T_{n+j})T$ *)
val to_lambda : int -> constr -> constr
val to_prod : int -> constr -> constr

(* pseudo-reduction rule *)
(* [prod_applist] $(x1:B1;...;xn:Bn)B a1...an \rightarrow B[a1...an]$ *)
val prod_applist : constr -> constr list -> constr

(*s Other term destructors. *)

(* Transforms a product term $(x_1:T_1)..(x_n:T_n)T$ into the pair
   $([(x_n,T_n);...;(x_1,T_1)],T)$, where $T$ is not a product. *)
val decompose_prod : constr -> (name*constr) list * constr

(* Transforms a lambda term $[x_1:T_1]..[x_n:T_n]T$ into the pair
   $([(x_n,T_n);...;(x_1,T_1)],T)$, where $T$ is not a lambda. *)
val decompose_lam : constr -> (name*constr) list * constr

(* Given a positive integer n, transforms a product term 
   $(x_1:T_1)..(x_n:T_n)T$
   into the pair $([(xn,Tn);...;(x1,T1)],T)$. *)
val decompose_prod_n : int -> constr -> (name*constr) list * constr

(* Given a positive integer $n$, transforms a lambda term 
   $[x_1:T_1]..[x_n:T_n]T$ into the pair $([(x_n,T_n);...;(x_1,T_1)],T)$ *)
val decompose_lam_n : int -> constr -> (name*constr) list * constr

(* [nb_lam] $[x_1:T_1]...[x_n:T_n]c$ where $c$ is not an abstraction
   gives $n$ (casts are ignored) *)
val nb_lam : constr -> int

(* similar to [nb_lam], but gives the number of products instead *)
val nb_prod : constr -> int


(*s Various utility functions for implementing terms with bindings. *)

val extract_lifted : int * constr -> constr
val insert_lifted : constr -> int * constr

(* If [l] is a list of pairs $(n:nat,x:constr)$, [env] is a stack of 
   $(na:name,T:constr)$, then
   [push_and_lift (id,c) env l] adds a component [(id,c)] to [env] 
   and lifts [l] one step *)
val push_and_lift :
  name * constr -> (name * constr) list -> (int * constr) list 
    -> (name * constr) list * (int * constr) list

(* if [T] is not $(x_1:A_1)(x_2:A_2)....(x_n:A_n)T'$ 
   then [(push_and_liftl n env T l)]
   raises an error else it gives $([x1,A1 ; x2,A2 ; ... ; xn,An]@env,T',l')$
   where $l'$ is [l] lifted [n] steps *)
val push_and_liftl :
  int -> (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* if $T$ is not $[x_1:A_1][x_2:A_2]....[x_n:A_n]T'$ then 
   [(push_lam_and_liftl n env T l)]
   raises an error else it gives $([x_1,A_1; x_2,A_2; ...; x_n,A_n]@env,T',l')$
   where $l'$ is [l] lifted [n] steps *)
val push_lam_and_liftl :
  int -> (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* If [l] is a list of pairs $(n:nat,x:constr)$, [tlenv] is a stack of
   $(na:name,T:constr)$, [B] is a constr, [na] a name, then
   [(prod_and_pop ((na,T)::tlenv) B l)] gives $(tlenv, (na:T)B, l')$
   where $l'$ is [l] lifted down one step *)
val prod_and_pop :
  (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* recusively applies [prod_and_pop] :
   if [env] = $[na_1:T_1 ; na_2:T_2 ; ... ; na_n:T_n]@tlenv$ then
   [(prod_and_popl n env T l)] gives $(tlenv,(na_n:T_n)...(na_1:T_1)T,l')$
   where $l'$ is [l] lifted down [n] steps *)
val prod_and_popl :
  int -> (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* similar to [prod_and_pop], but gives $[na:T]B$ intead of $(na:T)B$ *)
val lam_and_pop :
  (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* similar to [prod_and_popl] but gives $[na_n:T_n]...[na_1:T_1]B$ instead of
   $(na_n:T_n)...(na_1:T_1)B$ *)
val lam_and_popl :
  int -> (name * constr) list -> constr -> (int * constr) list
    -> (name * constr) list * constr * (int * constr) list

(* similar to [lamn_and_pop] but generates new names whenever the name is 
   [Anonymous] *)
val lam_and_pop_named :
  (name * constr) list -> constr ->(int * constr) list ->identifier list 
    -> (name * constr) list * constr * (int * constr) list * identifier list

(* similar to [prod_and_popl] but gives $[na_n:T_n]...[na_1:T_1]B$ instead of
   but it generates names whenever $na_i$ = [Anonymous] *)
val lam_and_popl_named :
  int ->  (name * constr) list -> constr ->  (int * constr) list 
    -> (name * constr) list * constr * (int * constr) list 

(* [lambda_ize n T endpt]
   will pop off the first [n] products in [T], then stick in [endpt],
   properly lifted, and then push back the products, but as lambda-
   abstractions *)
val lambda_ize : int ->'a oper term -> 'a oper term -> 'a oper term


(*s Flattening and unflattening of embedded applications and casts. *)

(* if [c] is not an [AppL], it is transformed into [mkAppL [| c |]] *)
val ensure_appl : constr -> constr

(* unflattens application lists *)
val telescope_appl : constr -> constr
(* flattens application lists *)
val collapse_appl : constr -> constr
val decomp_app : constr -> constr * constr list


(*s Misc functions on terms, sorts and conversion problems. *)

(* Level comparison for information extraction : Prop <= Type *)
val same_kind : constr -> constr -> bool
val le_kind : constr -> constr -> bool
val le_kind_implicit : constr -> constr -> bool

val sort_hdchar : sorts -> string


(*s Occur check functions. *)                         

val occur_meta : constr -> bool
val occur_existential : constr -> bool
val rel_vect : int -> int -> constr array

(* [(occur_const (s:section_path) c)] returns [true] if constant [s] occurs 
   in c, [false] otherwise *)
val occur_const : section_path -> constr -> bool

(* strips head casts and flattens head applications *)
val strip_head_cast : constr -> constr
val whd_castapp_stack : constr -> constr list -> constr * constr list
val whd_castapp : constr -> constr
val rename_bound_var : identifier list -> constr -> constr
val eta_reduce_head : constr -> constr
val eq_constr : constr -> constr -> bool
val eta_eq_constr : constr -> constr -> bool
val subst_term : constr -> constr -> constr
val subst_term_eta_eq : constr -> constr -> constr
val replace_consts :
  (section_path * (identifier list * constr) option) list -> constr -> constr
val subst_term_occ : int list -> constr -> constr -> constr

(* [subst_meta bl c] substitutes the metavar $i$ by $c_i$ in [c] 
   for each binding $(i,c_i)$ in [bl],
   and raises [Not_found] if [c] contains a meta that is not in the 
   association list *) 

val subst_meta : (int * constr) list -> constr -> constr


(*s Hash-consing functions for constr. *)

val hcons_constr:
  (section_path -> section_path) *
  (section_path -> section_path) *
  (name -> name) *
  (identifier -> identifier) *
  (string -> string) 
  ->
    (constr -> constr) *
    (constr -> constr) *
    (typed_type -> typed_type)

val hcons1_constr : constr -> constr