rudimentary abstract syntax type checker and solver in PGF

1 files changed, 5 insertions, 1 deletions

diff --git a/src/PGF/Expr.hs b/src/PGF/Expr.hs
index 51a076d36..55bd90441 100644
--- a/src/PGF/Expr.hs
+++ b/src/PGF/Expr.hs
@@ -4,7 +4,7 @@ module PGF.Expr(readTree, showTree, pTree, ppTree,
                 tree2expr, expr2tree,

 

                 -- needed in the typechecker

-                Value(..), Env, eval,

+                Value(..), Env, eval, apply,

 

                 -- helpers

                 pIdent,pStr

@@ -188,6 +188,7 @@ data Value
   | VMeta Int 

   | VLit Literal

   | VClosure Env Expr

+ deriving (Show,Eq,Ord)

 

 type Env = Map.Map CId Value

 

@@ -197,7 +198,10 @@ eval env (EApp e1 e2) = apply (eval env e1) (eval env e2)
 eval env (EAbs x e)   = VClosure env (EAbs x e)

 eval env (EMeta k)    = VMeta k

 eval env (ELit l)     = VLit l

+eval env e            = VClosure env e

 

 apply :: Value -> Value -> Value

 apply (VClosure env (EAbs x e)) v = eval (Map.insert x v env) e

 apply v0                        v = VApp v0 v

+

+