From afef9e63cb11267dc69b714a8b76415d75e2dd37 Mon Sep 17 00:00:00 2001
From: Josh Chen
Date: Sun, 10 Feb 2019 02:59:30 +0100
Subject: Type information storage functionality (assume_type, assume_types
 keywords) done! Inference and pretty-printing for function composition done.

---
 typing.ML | 205 ++++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 167 insertions(+), 38 deletions(-)

(limited to 'typing.ML')

diff --git a/typing.ML b/typing.ML
index bfe8409..4bcb633 100644
--- a/typing.ML
+++ b/typing.ML
@@ -6,15 +6,96 @@ Functionality for object-level type inference.
 
 ********)
 
+(* Context attribute for tracing; use declare[[trace=true]] at any point in a theory to turn on *)
+val trace = Attrib.setup_config_bool @{binding "trace"} (K false)
+
+(* ====================================== Helper functions ====================================== *)
+
+signature TYPING_LIB =
+sig
+  (* Lexical functions *)
+  val unmark: string -> string
+  
+  (* General functions *)
+  val get_all_thms: Proof.context -> (string * thm) list
+  val find_thm: Proof.context -> string -> (string * thm) list
+  
+  (* Get specific theorems *)
+  val get_this: Proof.context -> thm list
+  val get_assms: Proof.context -> thm list
+end
+
+structure Typing_Lib: TYPING_LIB =
+struct
+
+fun unmark s =
+  Lexicon.unmark_class s
+  handle Fail "unprefix" =>
+  Lexicon.unmark_type s
+  handle Fail "unprefix" =>
+  Lexicon.unmark_const s
+  handle Fail "unprefix" =>
+  Lexicon.unmark_fixed s
+  handle Fail "unprefix" =>
+  s
+
+fun name_and_thm (fact, thm) =
+  ((case fact of
+    Facts.Named ((name, _), _) => name
+  | Facts.Fact name => name),
+  thm)
+
+fun get_all_thms ctxt =
+  let val (_, ref_thms) = Find_Theorems.find_theorems ctxt NONE NONE true []
+  in ref_thms |> (map name_and_thm)
+  end
+
+(* Search all visible theorems (including local assumptions) containing a given name *)
+fun find_thm ctxt name =
+  let val (_, ref_thms) =
+    Find_Theorems.find_theorems ctxt NONE NONE true [(true, Find_Theorems.Name name)]
+  in
+    ref_thms |> (map name_and_thm)
+  end
+
+(* Get the fact corresponding to the Isar term "this" in the current proof scope *)
+fun get_this ctxt =
+  Proof_Context.get_fact ctxt (Facts.named "local.this")
+  handle ERROR "Undefined fact: \"local.this\"" => (
+    if (Config.get ctxt trace) then warning "\"this\" undefined in the context" else ();
+    []
+  )
+
+(* Get all visible assumptions in the current proof scope.
+   This includes the facts introduced in the statement of the goal using "assumes",
+   as well as all facts introduced using "assume" that are visible in the current block.
+ *)
+val get_assms = Assumption.all_prems_of
+
+end
+
+(* ================================ Type inference functionality ================================ *)
+
 signature TYPING =
 sig
   type jmt = term
+  val is_typing_jmt: term -> bool
   val term_of_jmt: jmt -> term
   val type_of_jmt: jmt -> term
+
+  val typing_this: Proof.context -> jmt list
   val typing_assms: Proof.context -> jmt list
-  val get_typing: term -> jmt list -> term option
-  val get_global_typing: theory -> Proof.context -> term -> term option
-  val tm_of_ptm: Proof.context -> term -> term
+  val typing_all: Proof.context -> jmt list
+
+  val get_typing_in: term -> jmt list -> term option
+  val get_local_typing: Proof.context -> term -> term option
+
+  val get_declared_typing: theory -> term -> term option
+  val put_declared_typing: term -> theory -> theory
+
+  val get_typing: Proof.context -> term -> term option
+
+  val prep_term: Proof.context -> term -> term
 end
 
 structure Typing: TYPING =
@@ -22,6 +103,10 @@ struct
 
 type jmt = term
 
+(* Determine if a term is a typing judgment *)
+fun is_typing_jmt (@{const has_type} $ _ $ _) = true
+  | is_typing_jmt _ = false
+
 (* Functions to extract a and A from propositions "a: A" *)
 fun term_of_jmt (@{const has_type} $ t $ _) = t
   | term_of_jmt _ = Exn.error "Not a typing judgment"
@@ -29,62 +114,106 @@ fun term_of_jmt (@{const has_type} $ t $ _) = t
 fun type_of_jmt (@{const has_type} $ _ $ T) = T
   | type_of_jmt _ = Exn.error "Not a typing judgment"
 
+(* Get typing assumptions in "this" *)
+fun typing_this ctxt = Typing_Lib.get_this ctxt |> map Thm.prop_of |> filter is_typing_jmt
+
 (* Get the typing assumptions in the current context *)
-fun typing_assms ctxt =
-  let
-    fun is_typing_jmt (@{const has_type} $ _ $ _) = true
-      | is_typing_jmt _ = false
-  in
-    Assumption.all_prems_of ctxt |> map Thm.prop_of |> filter is_typing_jmt
-  end
+val typing_assms = Typing_Lib.get_assms #> map Thm.prop_of #> filter is_typing_jmt
 
-(* Search for a term typing in a list of judgments*)
-fun get_typing tm jmts =
+(* Get all visible typing judgments—Quick hack for now; should record them separately *)
+fun typing_all ctxt =
+  Typing_Lib.get_all_thms ctxt |> map (Thm.prop_of o snd) |> filter is_typing_jmt
+
+(* Search for a term typing in a list of judgments, and return the type if found.
+   --
+   The use of aconv_untyped as opposed to aconv is crucial here:
+   meta-level type inference is performed *after* syntax translation, which means that
+   the translation functions see an unannotated term "f" (in contrast to one annotated
+   e.g. "f::t") as having a blank type field.
+   Using aconv would result in no match ever being found for f, because any judgment
+   involving f records it together with its (non-blank) type field, e.g.
+     "Free ("f", "_")"
+   seen by the translation function, vs.
+     "Free ("f", "t")"
+   recorded in the typing judgment.
+*)
+fun get_typing_in tm jmts =
   let val find_type =
         fn jmt => if Term.aconv_untyped (tm, term_of_jmt jmt) then SOME (type_of_jmt jmt) else NONE
   in get_first find_type jmts end
 
-(* Private storage space for global typing data *)
-structure Typing_Data = Theory_Data
+(* Search for typing in the local proof context (no global data).
+   We search the facts bound to "this" before searching the assumptions.
+   --
+   A previous version of this function passed the argument
+    (typing_this ctxt @ typing_assms ctxt)
+   to get_typing_in.
+   --
+   This version only evaluates successive lists if the search on the previous list was unsuccessful.
+*)
+fun get_local_typing ctxt tm =
+  case get_typing_in tm (typing_this ctxt) of
+    NONE => get_typing_in tm (typing_assms ctxt)
+  | res => res
+
+(* Storage space for declared typings *)
+structure Declared_Typings = Theory_Data
 (
   type T = term Symtab.table
   val empty = Symtab.empty
   val extend = I
-
-  fun merge (tbl, tbl') =
-    let
-      val key_vals = map (Symtab.lookup_key tbl') (Symtab.keys tbl')
-      val updates = map (fn SOME kv => Symtab.update kv) key_vals
-      fun f u t = u t
-    in fold f updates tbl end
+  val merge = K Symtab.empty
 )
-
 (* Accessor for the above data *)
-fun get_global_typing thy ctxt tm = Symtab.lookup (Typing_Data.get thy) (Syntax.string_of_term ctxt tm)
+fun get_declared_typing thy tm =
+  case tm of
+    (Free (v, _)) => Symtab.lookup (Declared_Typings.get thy) v
+  | _ => NONE
+
+(* Store new typing information for free variables only
+   (constants should have their types declared at the moment of definition).
+   End users should use the "typing" keyword instead.
+*)
+fun put_declared_typing jmt =
+  case jmt of
+    Const("HoTT_Base.has_type", _) $ term $ typing =>
+      (case term of
+        Free (v, _) => Declared_Typings.map (Symtab.update (v, typing))
+      | _ => Exn.error "Cannot declare typing assumption (not a free variable)")
+  | _ => Exn.error "Not a typing judgment"
+
+(* Get the typing of a term *)
+fun get_typing ctxt tm =
+  case get_local_typing ctxt tm of
+    NONE => get_declared_typing (Proof_Context.theory_of ctxt) tm
+  | res => res
 
-(* Convert a Pure pre-term to an unchecked Pure term *)
-fun tm_of_ptm ctxt ptm =
+(* Prepare a Pure pre-term, converting it partway to a (unchecked) term *)
+fun prep_term ctxt ptm =
   let val ptm = Term_Position.strip_positions ptm
   in
   (case ptm of
-    Const ("_constrain", _) $ Free (t, _) $ (Const ("\<^type>fun", _) $ Const(n1, _) $ Const (n2, _)) =>
+    Const ("_constrain", _) $ Free (t, _) $
+    (Const ("\<^type>fun", _) $ Const(typ1, _) $ Const (typ2, _)) =>
       let
-        val typ1 = unprefix "\<^type>" n1
-        val typ2 = unprefix "\<^type>" n2
+        val typ1 = Lexicon.unmark_type typ1
+        val typ2 = Lexicon.unmark_type typ2
         val typ = typ1 ^ "\<Rightarrow>" ^ typ2 |> Syntax.read_typ ctxt
       in Free (t, typ) end
-  | Const ("_constrain", _) $ Free (t, _) $ Const (T, _) =>
-      Free (t, Syntax.read_typ ctxt (unprefix "\<^type>" T))
+  | Const ("_constrain", _) $ t $ Const (typ, _) =>
+      let 
+        val T = Syntax.read_typ ctxt (Lexicon.unmark_type typ)
+      in
+        case t of
+          Free (s, _) => Free (s, T)
+        | Const (s, _) => Const (Lexicon.unmark_const s, T)
+        | _ => Exn.error "Unimplemented term constraint handler"
+      end
   | ptm1 $ ptm2 =>
-      (tm_of_ptm ctxt ptm1) $ (tm_of_ptm ctxt ptm2)
-  | Const (t, T) =>
-      let val t' =
-        unprefix "\<^const>" t handle Fail "unprefix" =>
-        unprefix "\<^type>" t handle Fail "unprefix" =>
-        t
-      in Const (t', T) end
+      (prep_term ctxt ptm1) $ (prep_term ctxt ptm2)
   | Abs (t, T, ptm') =>
-      Abs (t, T, tm_of_ptm ctxt ptm')
+      Abs (t, T, prep_term ctxt ptm')
+  | Const (t, T) => Const (Typing_Lib.unmark t, T)
   | t => t)
   end
 
-- 
cgit v1.2.3