bugfix: restore the check for bound variables in expr2tree

1 files changed, 17 insertions, 15 deletions

diff --git a/src/PGF/Expr.hs b/src/PGF/Expr.hs
index 0058c0463..90b1af64a 100644
--- a/src/PGF/Expr.hs
+++ b/src/PGF/Expr.hs
@@ -214,22 +214,24 @@ tree2expr (Var x)    = EVar x
 -- | Converts an expression to tree. The conversion is only partial.

 -- Variables and meta variables of function type and beta redexes are not allowed.

 expr2tree :: Expr -> Tree

-expr2tree e = abs [] e

+expr2tree e = abs [] [] e

   where

-    abs xs (EAbs x e) = abs (x:xs) e

-    abs xs e          = case xs of

-                          [] -> app [] e

-                          xs -> Abs (reverse xs) (app [] e)

-

-    app as (EApp e1 e2)   = app ((abs [] e2) : as) e1

-    app as (ELit l)

-              | null as   = Lit l

-              | otherwise = error "literal of function type encountered"

-    app as (EMeta n)

-              | null as   = Meta n

-              | otherwise = error "meta variables of function type are not allowed in trees"

-    app as (EAbs x e)     = error "beta redexes are not allowed in trees"

-    app as (EVar x)       = Fun x as

+    abs ys xs (EAbs x e) = abs ys (x:xs) e

+    abs ys xs e          = case xs of

+                             [] -> app ys [] e

+                             xs -> Abs (reverse xs) (app (xs++ys) [] e)

+

+    app xs as (EApp e1 e2)   = app xs ((abs xs [] e2) : as) e1

+    app xs as (ELit l)

+               | null as     = Lit l

+               | otherwise   = error "literal of function type encountered"

+    app xs as (EMeta n)

+               | null as     = Meta n

+               | otherwise   = error "meta variables of function type are not allowed in trees"

+    app xs as (EAbs x e)     = error "beta redexes are not allowed in trees"

+    app xs as (EVar x)

+               | x `elem` xs = Var x

+               | otherwise   = Fun x as

 

 

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