More work on the new partial evaluator

The work done by the partial evaluator is now divied in two stages:
 - A static "term traversal" stage that happens only once per term and uses
   only statically known information. In particular, the values of lambda bound
   variables are unknown during this stage. Some tables are transformed to
   reduce the cost of pattern matching.
 - A dynamic "function application" stage, where function bodies can be
   evaluated repeatedly with different arguments, without the term traversal
   overhead and without recomputing statically known information.

Also the treatment of predefined functions has been reworked to take advantage
of the staging and better handle partial applications.

src/compiler/GF/Compile/Compute/Value.hs

@@ -3,10 +3,11 @@ import GF.Grammar.Grammar(Label,Type,TInfo,MetaId,Patt,QIdent)
 import PGF.Data(BindType)
 import GF.Infra.Ident(Ident)
 import Text.Show.Functions
+import Data.Ix(Ix)
 
 -- | Self-contained (not quite) representation of values
 data Value
-  = VApp QIdent [Value] -- from Q, always Predef.x, has a built-in value
+  = VApp Predefined [Value] -- from Q, always Predef.x, has a built-in value
   | VCApp QIdent [Value] -- from QC, constructors
   | VGen Int [Value] -- for lambda bound variables, possibly applied
   | VMeta MetaId Env [Value]
@@ -22,7 +23,7 @@ data Value
   | VRecType [(Label,Value)]
   | VRec [(Label,Value)]
   | VV Type [Value] [Value] -- preserve type for conversion back to Term
-  | VT TInfo [(Patt,Bind Env)]
+  | VT Wild Value [(Patt,Bind Env)]
   | VC Value Value
   | VS Value Value
   | VP Value Label
@@ -36,9 +37,19 @@ data Value
   | VError String
   deriving (Eq,Show)
 
+type Wild = Bool
 type Binding = Bind Value
 data Bind a = Bind (a->Value) deriving Show
 
 instance Eq (Bind a) where x==y = False
 
 type Env = [(Ident,Value)]
+
+-- | Predefined functions
+data Predefined = Drop | Take | Tk | Dp | EqStr | Occur | Occurs | ToUpper
+                | ToLower | IsUpper | Length | Plus | EqInt | LessInt 
+             {- | Show | Read | ToStr | MapStr | EqVal -}
+                | Error
+                -- Canonical values below:
+                | PBool | PFalse | PTrue | Ints
+                deriving (Show,Eq,Ord,Ix,Bounded,Enum)