From: Adam Chlipala <adamc@hcoop.net>
Date: Sat, 15 Dec 2007 21:05:09 +0000 (+0000)
Subject: Hint Monster
X-Git-Tag: release_2010-11-19~82
X-Git-Url: https://git.hcoop.net/hcoop/domtool2.git/commitdiff_plain/113d72170910c3dd0e9b49c6b46a8ae42df66ab8

Hint Monster
---

diff --git a/src/describe.sig b/src/describe.sig
index 268a9e1..8333c26 100644
--- a/src/describe.sig
+++ b/src/describe.sig
@@ -26,6 +26,6 @@ signature DESCRIBE = sig
 
     val describe_type_error : Ast.position -> Ast.type_error -> unit
 
-
+    val ununify : Ast.typ -> Ast.typ
 
 end
diff --git a/src/describe.sml b/src/describe.sml
index a753ddb..1e81550 100644
--- a/src/describe.sml
+++ b/src/describe.sml
@@ -116,7 +116,18 @@ fun get_first_arg (t, _) =
       | TUnif (_, ref (SOME t')) => get_first_arg t'
       | _ => raise Fail "get_first_arg failed!"
 
-fun describe_type_error loc te =
+fun hint te =
+    case te of
+	WrongType (_, _, (TBase "string", _), (TBase "your_domain", _), _) =>
+	SOME "Did you forget to request permission to configure this domain?  See:\n\thttps://members.hcoop.net/portal/domain"
+      | WrongType (_, (EString dom, _), (TBase "string", _), (TBase "domain", _), _) =>
+	if CharVector.exists Char.isUpper dom then
+	    SOME "Uppercase letters aren't allowed in domain strings."
+	else
+	    NONE
+      | _ => NONE
+
+fun describe_type_error' loc te =
     case te of
 	WrongType (place, e, t1, t2, ueo) =>
 	(ErrorMsg.error (SOME loc) (place ^ " has wrong type.");
@@ -141,4 +152,29 @@ fun describe_type_error loc te =
 	 preface ("Have:", p_pred p1);
 	 preface ("Need:", p_pred p2))
 
+fun ununify (tAll as (t, _)) =
+    case t of
+	TUnif (_, ref (SOME t)) => ununify t
+      | _ => tAll
+
+fun normalize_error err =
+    case err of
+	WrongType (s, e, t1, t2, ueo) =>
+	WrongType (s, e, ununify t1, ununify t2, ueo)
+      | WrongForm (s1, s2, e, t, ueo) =>
+	WrongForm (s1, s2, e, ununify t, ueo)
+      | UnboundVariable _ => err
+      | WrongPred _ => err
+
+fun describe_type_error loc te =
+    let
+	val te = normalize_error te
+    in
+	describe_type_error' loc te;
+	Option.app (fn s => (print "Hint Monster says:\n";
+			     print s;
+			     print "\n"))
+		   (hint te)
+    end
+
 end
diff --git a/src/tycheck.sml b/src/tycheck.sml
index d5b3f1e..d83a5c0 100644
--- a/src/tycheck.sml
+++ b/src/tycheck.sml
@@ -258,10 +258,7 @@ fun envVarSetFrom v (e, _) =
 
       | _ => NONE
 
-fun ununify (tAll as (t, _)) =
-    case t of
-	TUnif (_, ref (SOME t)) => ununify t
-      | _ => tAll
+val ununify = Describe.ununify
 
 fun checkExp G (eAll as (e, loc)) =
     let