diff --git a/3or4/Interpreter/Self.hs b/3or4/Interpreter/Self.hs
index 0ff6951..76a38e6 100644
--- a/3or4/Interpreter/Self.hs
+++ b/3or4/Interpreter/Self.hs
@@ -47,18 +47,41 @@ substBrExp =
 
 substExp :: Exp
 substExp =
-  subst (Variable "if") ifExp .
-  subst (Variable "equal") equalExp .
-  subst (Variable "substBr") substBrExp .
-  subst (Variable "map") mapExp $ parse
-        "\\var. \\e. rec subst = \\x. case x of\
-        \ { Apply(e1,e2) -> Apply(subst e1, subst e2) \
-        \ ; Lambda(x,y) -> if (equal x var) Lambda(x,y) Lambda(x,subst y) \
-        \ ; Var(x) -> if (equal x var) e Var(x) \
-        \ ; Const(c,es) -> Const(c, map subst es) \
-        \ ; Rec(x, e') -> if (equal x var) Rec(x,e') Rec(x,subst e')\
-        \ ; Case(e',bs) -> Case(subst e', map (substBr subst var) bs) \
-        \ }"
+  parse
+  "( \\map. \\substBr. \\elem. \\equal. \\if. \\var. \\e. rec subst = \\x. case x of\
+  \ { Apply(e1,e2) -> Apply(subst e1, subst e2) \
+  \ ; Lambda(x,y) -> if (equal x var) Lambda(x,y) Lambda(x,subst y) \
+  \ ; Var(x) -> if (equal x var) e Var(x) \
+  \ ; Const(c,es) -> Const(c, map subst es) \
+  \ ; Rec(x, e') -> if (equal x var) Rec(x,e') Rec(x,subst e')\
+  \ ; Case(e',bs) -> Case(subst e', map (substBr subst var) bs) \
+  \ }) \
+  \  \
+  \ -- map \
+  \ (\\f. rec map = \\xs. case xs of \
+  \ { Nil() -> Nil() \
+  \ ; Cons(x,xs) -> Cons(f x, map xs)\
+  \ }) \
+  \ -- substBr \
+  \ (\\subst. \\var. \\b. case b of \
+  \ { Branch(c,vs,e') -> if (elem var vs) Branch(c,vs,e') Branch(c,vs, subst e') \
+  \ }) \
+  \ -- elem \
+  \ (\\x. rec elem = \\l. case l of \
+  \ { Nil() -> False() \
+  \ ; Cons(v,vs) -> if (equal x v) True() (elem vs)\ 
+  \ }) \
+  \ -- equal \
+  \ (rec equal = \\m. \\n. case m of \
+  \ { Zero() -> case n of { Zero() -> True(); Suc(n) -> False() } \
+  \ ; Suc(m) -> case n of { Zero() -> False(); Suc(n) -> equal m n }\
+  \ }) \
+  \ -- if \
+  \ (\\b. \\t. \\f. case b of \
+  \ { True() -> t \
+  \ ; False() -> f \
+  \ }) \
+  \"
 
 -- Task 4
 
@@ -67,7 +90,6 @@ lookupExp =
   subst (Variable "if") ifExp .
   subst (Variable "equal") equalExp $ parse
   "\\c. rec lookup = \\xs. case xs of \
-  \ -- TODO: Fix for Nil() \
   \ { Cons(b,bs) -> \
   \     case b of \
   \       { Branch(c', xs, e') -> if (equal c c') Pair(xs,e') (lookup bs) } \