From 8f4ff41d24dd8fa6844312456d47cad4be6cb239 Mon Sep 17 00:00:00 2001
From: Josh Chen
Date: Sun, 9 Aug 2020 18:34:58 +0200
Subject: (FEAT) Clean up typechecking/elaboration tactic: known_ctac should
 *solve* goals; resolving with conditional typing judgments (e.g. type family
 assumptions) is part of check_infer_step

---
 spartan/core/tactics.ML      |  4 ++--
 spartan/core/typechecking.ML | 19 ++++++++++---------
 2 files changed, 12 insertions(+), 11 deletions(-)

(limited to 'spartan')

diff --git a/spartan/core/tactics.ML b/spartan/core/tactics.ML
index 446af15..45fd119 100644
--- a/spartan/core/tactics.ML
+++ b/spartan/core/tactics.ML
@@ -82,8 +82,8 @@ fun internalize_fact_tac t =
         Drule.infer_instantiate' ctxt [NONE, NONE, SOME B, SOME a] @{thm PiE}
     in
       HEADGOAL (resolve_tac ctxt [resolvent])
-      (*known_tac infers the correct type T inferred by unification*)
-      THEN SOMEGOAL (NO_CONTEXT_TACTIC ctxt o Types.known_ctac [])
+      (*Infer the correct type T*)
+      THEN SOMEGOAL (NO_CONTEXT_TACTIC ctxt o Types.check_infer [])
     end)
 
 fun elim_core_tac tms types ctxt =
diff --git a/spartan/core/typechecking.ML b/spartan/core/typechecking.ML
index b7a7f9b..ca89c8c 100644
--- a/spartan/core/typechecking.ML
+++ b/spartan/core/typechecking.ML
@@ -50,18 +50,15 @@ fun known_ctac facts = CONTEXT_SUBGOAL (fn (goal, i) => fn (ctxt, st) =>
       if Lib.no_vars concl orelse
         (Lib.is_typing concl andalso Lib.no_vars (Lib.term_of_typing concl))
       then
-        let val ths = map (Simplifier.norm_hhf ctxt)
-          (facts @ map fst (Facts.props (Proof_Context.facts_of ctxt)))
-          (*FIXME: Shouldn't pull nameless facts directly from context*)
-        in
-          (debug_tac ctxt "resolve" THEN resolve_tac ctxt ths i ORELSE
-          debug_tac ctxt "assume" THEN assume_tac ctxt i) st
+        let val ths = map (Simplifier.norm_hhf ctxt) facts
+        in st |>
+          (assume_tac ctxt ORELSE' resolve_tac ctxt ths THEN_ALL_NEW K no_tac) i
         end
       else Seq.empty
     end)
 
 (*Simple bidirectional typing tactic, with some nondeterminism from backtracking
-  search over arbitrary `typechk` rules. The current implementation does not
+  search over arbitrary `type` rules. The current implementation does not
   perform any normalization.*)
 fun check_infer_step facts i (ctxt, st) =
   let
@@ -69,8 +66,12 @@ fun check_infer_step facts i (ctxt, st) =
       if Lib.rigid_typing_concl goal
       then
         let val net = Tactic.build_net (
-          map (Simplifier.norm_hhf ctxt) facts
-          (*MAYBE FIXME: Remove `typechk` from this list, and instead perform
+          map (Simplifier.norm_hhf ctxt)
+            (*FIXME: Shouldn't pull nameless facts directly from context. Note
+              that we *do* need to be able to resolve with conditional
+              statements expressing type family judgments*)
+            (facts @ map fst (Facts.props (Proof_Context.facts_of ctxt)))
+          (*MAYBE FIXME: Remove `type` from this list, and instead perform
             definitional unfolding to (w?)hnf.*)
           @(Named_Theorems.get ctxt \<^named_theorems>\<open>type\<close>)
           @(Named_Theorems.get ctxt \<^named_theorems>\<open>form\<close>)
-- 
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