* interp/compiler.boot (compOrCroak1): Drop last argument. Tidy.

	(mostSpecificTriple): New.
	(compAtomWithModemap): Use it to resolve ambiguous constants.
	(formatConstantCandidates): New.
	(compForm1): Do try to compile constants 0 and 1 with compToApply.
	* algebra/polycat.spad.pamphlet (FiniteAbelianMonoidRing)
	[binomThmExpt]:  Tidy.
	(UnivariatePolynomialCategory) [pseudoDivide]: Likewise.
	* algebra/float.spad.pamphlet (Float) [log]: Specificy type for
	local variable `l'.
	* interp/format.boot (formatUnabbreviatedSig): Handle constants.

7 files changed, 70 insertions, 21 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 10413a15..8cc632b0 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,19 @@
 2011-10-23  Gabriel Dos Reis  <gdr@cs.tamu.edu>
 
+	* interp/compiler.boot (compOrCroak1): Drop last argument.  Tidy.
+	(mostSpecificTriple): New.
+	(compAtomWithModemap): Use it to resolve ambiguous constants.
+	(formatConstantCandidates): New.
+	(compForm1): Do try to compile constants 0 and 1 with compToApply.
+	* algebra/polycat.spad.pamphlet (FiniteAbelianMonoidRing)
+	[binomThmExpt]:  Tidy.
+	(UnivariatePolynomialCategory) [pseudoDivide]: Likewise.
+	* algebra/float.spad.pamphlet (Float) [log]: Specificy type for
+	local variable `l'.
+	* interp/format.boot (formatUnabbreviatedSig): Handle constants.
+
+2011-10-23  Gabriel Dos Reis  <gdr@cs.tamu.edu>
+
 	* interp/g-opt.boot ($VMsideEffectFreeOperators): Include %fdecode.
 	* interp/lisp-backend.boot: Expand it.
 	* algebra/sf.spad.pamphlet (DoubleFloat): Remove %fmanexpr import.
diff --git a/src/algebra/float.spad.pamphlet b/src/algebra/float.spad.pamphlet
index 26c0c253..7c5a74ae 100644
--- a/src/algebra/float.spad.pamphlet
+++ b/src/algebra/float.spad.pamphlet
@@ -423,7 +423,10 @@ Float():
       p := bits(); inc 5
       -- apply  log(x) = n log 2 + log(x/2**n)  so that  1/2 < x < 2
       if negative?(n := order x) then n := n+1
-      l := if n = 0 then 0 else (x := shift(x,-n); n * log2())
+      l: % :=
+        n = 0 => 0
+        x := shift(x,-n)
+        n * log2()
       -- speed the series convergence by finding m and k such that
       -- | exp(m/2**k) x - 1 |  <  1 / 2 ** O(sqrt p)
       -- write  log(exp(m/2**k) x) as m/2**k + log x
diff --git a/src/algebra/fraction.spad.pamphlet b/src/algebra/fraction.spad.pamphlet
index 6fecb082..f7d5d6e0 100644
--- a/src/algebra/fraction.spad.pamphlet
+++ b/src/algebra/fraction.spad.pamphlet
@@ -543,7 +543,7 @@ Fraction(S: IntegralDomain): QuotientFieldCategory S with
           makeFR(map(#1::%/den1,unit(ff)),lfact)
        factorSquareFreePolynomial(pp) ==
           zero? pp => 0
-          degree pp = 0 => makeFR(pp,empty())
+          zero? degree pp => makeFR(pp,empty())
           lcpp:=leadingCoefficient pp
           pp:=pp/lcpp
           denpp:="lcm"/[denom u for u in coefficients pp]
diff --git a/src/algebra/polycat.spad.pamphlet b/src/algebra/polycat.spad.pamphlet
index 4347438f..b56c9a97 100644
--- a/src/algebra/polycat.spad.pamphlet
+++ b/src/algebra/polycat.spad.pamphlet
@@ -142,7 +142,10 @@ FiniteAbelianMonoidRing(R:Ring, E:OrderedAbelianMonoid): Category ==
                bincoef: Integer
                powl: List(%):= [x]
                for i in 2..nn repeat powl:=[x * powl.first, :powl]
-               yn:=y; ans:=powl.first; i:=1; bincoef:=nn
+               yn := y
+               ans := powl.first
+               i: Integer := 1
+               bincoef := nn
                for xn in powl.rest repeat
                   ans:= bincoef * xn * yn + ans
                   bincoef:= (nn-i) * bincoef quo (i+1);  i:= i+1
@@ -918,7 +921,8 @@ UnivariatePolynomialCategory(R:Ring): Category ==
           - pseudoRemainder(p, q)) exquo q)::%
 
       pseudoDivide(p, q) ==
-        (n := degree(p)::Integer - degree q + 1) < 1 => [1, 0, p]
+        n: Integer := degree(p)::Integer - degree q + 1
+        n < 1 => [1, 0, p]
         prem := pseudoRemainder(p, q)
         lc   := leadingCoefficient(q)**(n::NonNegativeInteger)
         [lc,((lc*p - prem) exquo q)::%, prem]
diff --git a/src/interp/compiler.boot b/src/interp/compiler.boot
index 180edf0b..c6ffa376 100644
--- a/src/interp/compiler.boot
+++ b/src/interp/compiler.boot
@@ -50,7 +50,7 @@ module compiler where
 compUniquely: (%Form,%Mode,%Env) -> %Maybe %Triple
 compNoStacking: (%Form,%Mode,%Env) -> %Maybe %Triple
 compNoStacking1: (%Form,%Mode,%Env,%List %Thing) -> %Maybe %Triple
-compOrCroak1: (%Form,%Mode,%Env,%Thing) -> %Maybe %Triple
+compOrCroak1: (%Form,%Mode,%Env) -> %Maybe %Triple
 comp2: (%Form,%Mode,%Env) -> %Maybe %Triple
 comp3: (%Form,%Mode,%Env) -> %Maybe %Triple
 compExpression: (%Form,%Mode,%Env) -> %Maybe %Triple
@@ -106,17 +106,21 @@ compTopLevel(x,m,e) ==
         --keep old environment after top level function defs
   compOrCroak(x,m,e)
 
+
+++ True if no ambiguity is allowed in overload resolution.
+$compUniquelyIfTrue := false
+
 compUniquely(x,m,e) ==
   $compUniquelyIfTrue: local:= true
   CATCH("compUniquely",comp(x,m,e))
 
 compOrCroak(x,m,e) == 
-  compOrCroak1(x,m,e,'comp)
+  compOrCroak1(x,m,e)
 
-compOrCroak1(x,m,e,compFn) ==
-  fn(x,m,e,nil,nil,compFn) where
-    fn(x,m,e,$compStack,$compErrorMessageStack,compFn) ==
-      T:= CATCH("compOrCroak",FUNCALL(compFn,x,m,e)) => T
+compOrCroak1(x,m,e) ==
+  fn(x,m,e,nil,nil) where
+    fn(x,m,e,$compStack,$compErrorMessageStack) ==
+      T:= CATCH("compOrCroak",comp(x,m,e)) => T
       --stackAndThrow here and moan in UT LISP K does the appropriate THROW
       $compStack:= [[x,m,e,$exitModeStack],:$compStack]
       $s: local :=
@@ -359,25 +363,49 @@ compExpression(x,m,e) ==
     FUNCALL(fn,x,m,e)
   compForm(x,m,e)
 
-++ Subroutine of compAtom.
+++ Subroutine of compAtomWithModemap.
+++ `Ts' is list of (at least 2) triples.  Return the one with most
+++ specific mode.  Otherwise, return nil.
+mostSpecificTriple(Ts,e) ==
+  [T,:Ts] := Ts
+  and/[T := lesser(T,T',e) for T' in Ts] where
+    lesser(t,t',e) ==
+      isSubset(t.mode,t'.mode,e) => t
+      isSubset(t'.mode,t.mode,e) => t'
+      nil
+
 ++ Elaborate use of an overloaded constant.
 compAtomWithModemap: (%Symbol,%Mode,%Env,%List %Modemap) -> %Maybe %Triple
 compAtomWithModemap(x,m,e,mmList) ==
+  mmList := [mm for mm in mmList | mm.mmImplementation is ['CONST,:.]]
   mmList = nil => nil
+  name := -- constant name displayed in diagnostics.
+    -- FIXME: Remove when the parser is fixed.
+    x is 'Zero => "0"
+    x is 'One => "1"
+    x
   -- Try constants with exact type matches, first.
   Ts := [[['%call,first y],mm.mmTarget,e] for mm in mmList |
-           mm.mmImplementation is ['CONST,:.] and
              mm.mmTarget = m and
                (y := compViableModemap(x,nil,mm,e))]
   Ts is [T] => T            -- Only one possibility, take it.
-  Ts ~= nil => nil          -- Ambiguous constant.
+  Ts ~= nil =>              -- Ambiguous constant.
+    stackMessage('"Too many (%1b) constants named %2b with type %3pb",
+                  [#Ts,name,m])
   -- Fallback to constants that are coercible to the target.
-  Ts := [[['%call,first y],mm.mmTarget,e] for mm in mmList |
-           mm.mmImplementation is ['CONST,:.] and
+  Ts := [[['%call,first y],mm.mmTarget,nil] for mm in mmList |
              coerceable(mm.mmTarget,m,e) and
                (y := compViableModemap(x,nil,mm,e))]
-  Ts is [T] => coerce(T,m)
-  nil                       -- Couldn't make sense of it.
+  Ts = nil =>
+    stackMessage('"No viable constant named %1b in %2pb context",[name,m])
+  Ts is [T] or (T := mostSpecificTriple(Ts,e)) =>
+    coerce([T.expr,T.mode,e],m)
+  stackMessage('"Ambiguous constant %1b in %2pb constext.  Candidates are %3f",
+    [name,m,[function formatConstantCandidates,name,Ts]])
+
+++ Format constants named `op' with mode given in the list of triples `Ts'.
+formatConstantCandidates(op,Ts) ==
+  displayAmbiguousSignatures(op,[[T.mode,'constant] for T in Ts])
 
 compAtom(x,m,e) ==
   x is "break" => compBreak(x,m,e)
@@ -499,7 +527,9 @@ compForm1(form is [op,:argl],m,e) ==
       (T:= comp([op',:argl],domain,e) or return nil; coerce(T,m))
     nil
 
-  T:= compForm2(form,m,e,getFormModemaps(form,e)) => T
+  T := compForm2(form,m,e,getFormModemaps(form,e)) => T
+  --FIXME: remove next line when the parser is fixed.
+  form = $Zero or form = $One => nil
   compToApply(op,argl,m,e)
 
 compForm2(form is [op,:argl],m,e,modemapList) ==
diff --git a/src/interp/format.boot b/src/interp/format.boot
index 386a85cc..5f670131 100644
--- a/src/interp/format.boot
+++ b/src/interp/format.boot
@@ -818,6 +818,7 @@ formatUnabbreviatedSig sig ==
   [target,:args] := dollarPercentTran sig
   target := formatUnabbreviated target
   null args => ['"() -> ",:target]
+  args is ['constant] => target
   null rest args => [:formatUnabbreviated first args,'" -> ",:target]
   args := formatUnabbreviatedTuple args
   ['"(",:args,'") -> ",:target]
diff --git a/src/interp/sys-globals.boot b/src/interp/sys-globals.boot
index c9abeef9..31d062af 100644
--- a/src/interp/sys-globals.boot
+++ b/src/interp/sys-globals.boot
@@ -76,9 +76,6 @@ $clamList :=
 $compCount := 0
 
 ++
-$compUniquelyIfTrue := false
-
-++
 $createUpdateFiles := false
 
 ++