* interp/compiler.boot (compSymbol): Don't handle possible

	case views here.
	(hasUniqueCaseView): Rename from getUniqueCaseView.  Take the
	target mode as second argument.
	(compForm2): Use calling convention vector to determine infer flag
	parameter types.
	(compCase1): Uniformly handle `case-expressions'.  Call
	genDeltaEntry for selected operator.
	(coerceExtraHard): Handle coercions from UnionType domains.
	(autoCoerceByModemap): Tidy.
	* interp/g-opt.boot (optCall): Be more verbose in diagnostics.
	* algebra/syntax.spad (Syntax): Rework.
	* algebra/coerce.spad.pamphlet (UnionType): New.
	* algebra/Makefile.pamphlet (axiom_algebra_layer_0): 
	Include UTYPE.o
	* share/algebra: Update databases.

4 files changed, 34 insertions, 15 deletions

diff --git a/src/algebra/Makefile.in b/src/algebra/Makefile.in
index 3d9371db..a974ad21 100644
--- a/src/algebra/Makefile.in
+++ b/src/algebra/Makefile.in
@@ -377,7 +377,7 @@ axiom_algebra_layer_0 = \
   KOERCE.o  KONVERT.o MSYSCMD.o ODEIFTBL.o \
   OM.o      OMCONN.o  OMDEV.o   OUT.o      \
   PRIMCAT.o PRINT.o   PTRANFN.o SPFCAT.o   \
-  TYPE.o
+  TYPE.o    UTYPE.o
 
 axiom_algebra_layer_0_nrlibs = \
 	$(axiom_algebra_layer_0:.$(OBJEXT)=.NRLIB/code.$(OBJEXT))
diff --git a/src/algebra/Makefile.pamphlet b/src/algebra/Makefile.pamphlet
index c24752fb..45f1f2bd 100644
--- a/src/algebra/Makefile.pamphlet
+++ b/src/algebra/Makefile.pamphlet
@@ -205,7 +205,7 @@ axiom_algebra_layer_0 = \
   KOERCE.o  KONVERT.o MSYSCMD.o ODEIFTBL.o \
   OM.o      OMCONN.o  OMDEV.o   OUT.o      \
   PRIMCAT.o PRINT.o   PTRANFN.o SPFCAT.o   \
-  TYPE.o
+  TYPE.o    UTYPE.o
 
 axiom_algebra_layer_0_nrlibs = \
 	$(axiom_algebra_layer_0:.$(OBJEXT)=.NRLIB/code.$(OBJEXT))
diff --git a/src/algebra/coerce.spad.pamphlet b/src/algebra/coerce.spad.pamphlet
index 3ad352b6..f270bba6 100644
--- a/src/algebra/coerce.spad.pamphlet
+++ b/src/algebra/coerce.spad.pamphlet
@@ -2,7 +2,7 @@
 \usepackage{axiom}
 \begin{document}
 \title{\$SPAD/src/algebra coerce.spad}
-\author{Richard Jenks, Manuel Bronstein}
+\author{Richard Jenks, Manuel Bronstein, Gabriel Dos Reis}
 \maketitle
 \begin{abstract}
 \end{abstract}
@@ -20,6 +20,24 @@
 Type(): Category == with nil
 
 @
+
+
+\section{Category UnionType}
+
+<<category UTYPE UnionType>>=
+)abbrev category UTYPE UnionType
+++ Author: Gabriel Dos Reis
+++ Date Created: December 17, 2007
+++ Date Last Modified: December 17, 2007
+++ Description: The category of domains that act like unions.
+++ UnionType, like Type or Category, acts mostly as a take that
+++ communicates `union-like' intended semantics to the compiler.
+++ A domain D that satifies UnionType should provide definitions
+++ for `case' operators, with corresponding `autoCoerce' operators.
+UnionType(): Category == with nil
+@
+
+
 \section{category KOERCE CoercibleTo}
 <<category KOERCE CoercibleTo>>=
 )abbrev category KOERCE CoercibleTo
@@ -114,6 +132,7 @@ RetractableTo(S: Type): Category == with
 <<license>>
 
 <<category TYPE Type>>
+<<category UTYPE UnionType>>
 <<category KOERCE CoercibleTo>>
 <<category KONVERT ConvertibleTo>>
 <<category RETRACT RetractableTo>>
diff --git a/src/algebra/syntax.spad b/src/algebra/syntax.spad
index 2dd65ccb..b6331f4f 100644
--- a/src/algebra/syntax.spad
+++ b/src/algebra/syntax.spad
@@ -43,7 +43,7 @@
 ++ Fixme: Provide direct support for boolean values, arbritrary 
 ++        precision float point values.
 Syntax(): Public == Private where
-  Public ==> CoercibleTo(OutputForm) with
+  Public ==> Join(UnionType, CoercibleTo(OutputForm)) with
     convert: % -> SExpression
       ++ convert(s) returns the s-expression representation of a syntax.
 
@@ -55,26 +55,26 @@ Syntax(): Public == Private where
     coerce: Integer -> %
       ++ coerce(i) injects the integer value `i' into the Syntax domain
 
-    convert: % -> Integer
+    coerce: % -> Integer
       ++ coerce(i) extracts the integer value `i' from the Syntax domain
 
     coerce: DoubleFloat -> %
       ++ coerce(f) injects the float value `f' into the Syntax domain
 
-    convert: % -> DoubleFloat
-      ++ convert(f) extracts the float value `f' from the Syntax domain
+    coerce: % -> DoubleFloat
+      ++ coerce(f) extracts the float value `f' from the Syntax domain
 
     coerce: Symbol -> %
       ++ coerce(s) injects the symbol `s' into the Syntax domain.
 
-    convert: % -> Symbol
-      ++ convert(s) extracts the symbol `s' from the Syntax domain.
+    coerce: % -> Symbol
+      ++ coerce(s) extracts the symbol `s' from the Syntax domain.
 
     coerce: String -> %
       ++ coerce(s) injects the string value `s' into the syntax domain
 
-    convert: % -> String
-      ++ convert(s) extract the string value `s' from the syntax domain
+    coerce: % -> String
+      ++ coerce(s) extract the string value `s' from the syntax domain
 
     buildSyntax: (Symbol, List %) -> %
       ++ buildSyntax(op, [a1, ..., an]) builds a syntax object for op(a1,...,an).
@@ -135,28 +135,28 @@ Syntax(): Public == Private where
     coerce(i: Integer): % ==
       i pretend %
 
-    convert(i: %): Integer ==
+    ccoerce(i: %): Integer ==
       i case Integer => i
       userError "invalid conversion target type"
 
     coerce(f: DoubleFloat): % ==
       f pretend %
 
-    convert(f: %): DoubleFloat ==
+    coerce(f: %): DoubleFloat ==
       f case DoubleFloat => f
       userError "invalid conversion target type"
 
     coerce(s: Symbol): % ==
       s pretend %
 
-    convert(s: %): Symbol ==
+    coerce(s: %): Symbol ==
       s case Symbol => s
       userError "invalid conversion target type"
 
     coerce(s: String): % ==
       s pretend %
 
-    convert(s: %): String ==
+    coerce(s: %): String ==
       s case String => s
       userError "invalid conversion target type"