diff --git a/builtin.mjs b/builtin.mjs
index 3004340..df8cfc7 100644
--- a/builtin.mjs
+++ b/builtin.mjs
@@ -39,7 +39,7 @@ const root = (_, args) => {
 }
 
 const type = (_, args) => {
-    return [{type:"string", val:args[0].type}];
+    return [{type:"type", val:args[0].type}];
 }
 
 const pair = (_, args) => {
@@ -84,11 +84,12 @@ addDefn("snd", ["pair"], snd);
 addDefn("arr", ["int"], arr);
 addDefn("!!", ["int", "array"], index);
 addDefn("len", ["array"], len);
-addRPNDefn("unit", "(-> 0 arr)");
-addRPNDefn("mono", "(-> 1 arr)");
+//addRPNDefn("unit", "(-> 0 arr)");
+//addRPNDefn("mono", "(-> 1 arr)");
+//addRPNDefn("unwrap", "(-> 0 !!)");
 addRPNDefn("true", "(a b -> a)");
 addRPNDefn("false", "(a b -> b)");
 addRPNDefn("stop", "(-> \"stop)");
-addRPNDefn("id", "(a -> a)");
+//addRPNDefn("id", "(a -> a)");
 addRPNDefn("inv", "(x -> 1 x /)");
 addRPNDefn("fold", "(x acc fn -> '(-> acc) '(-> x acc fn 'fn fold) 'x \"stop ==)");
\ No newline at end of file
diff --git a/eval.mjs b/eval.mjs
index 4a26678..901e463 100644
--- a/eval.mjs
+++ b/eval.mjs
@@ -93,7 +93,7 @@ const lookupScope = (name, scope) => {
     if (n) {
         return cloneElem(n);
     } else {
-        throw "var " + n + " not in scope"
+        throw 'var "' + name + '" not in scope'
     }
 }
 
@@ -154,11 +154,24 @@ const doStep = (ins, stack) => {
     }
 }
 
+const showIns = (curr) => {
+    if (curr.type === "ident") {
+        return curr.val;
+    } else if (curr.type === "push") {
+        return "'" + showIns(curr.elem)
+    }
+}
+
 export const execRPN = (scope, i) => {
     let ins = JSON.parse(JSON.stringify(i));
     let stack = {scope:scope, stack:[]};
     while (ins.length > 0) {
-        doStep(ins, stack);
+        let curr = ins[0];
+        try {
+            doStep(ins, stack);
+        } catch (error) {
+            throw error + ' while executing "' + showIns(curr) + '"'
+        }
     }
     return stack;
 }
\ No newline at end of file
diff --git a/parse.mjs b/parse.mjs
index 9029456..efa0c0c 100644
--- a/parse.mjs
+++ b/parse.mjs
@@ -144,7 +144,7 @@ const parseName = (stream) => {
     return {parsed:id.parsed.val, stream:syn.stream};
 }
 
-const parseString = (stream) => {
+const parseType = (stream) => {
     
     let syn = attempt(parseSyntax("\""))(stream);
     if (syn.parsed === null) {
@@ -154,7 +154,7 @@ const parseString = (stream) => {
     if (id.parsed === null) {
         return {parsed:null, stream:id.stream};
     }
-    return {parsed:{type:"string", val:id.parsed.val}, stream:id.stream};
+    return {parsed:{type:"type", val:id.parsed.val}, stream:id.stream};
     
     //return {parsed:null, stream:stream};
 }
@@ -193,7 +193,7 @@ const parseLambda = (stream) => {
 }
 
 /* takes in stream, outputs parsed item or null */
-const parseExpr = or(parseString, or(parseIdent, or(parseInteger, or(parsePush, attempt(parens(parseLambda))))));
+const parseExpr = or(parseType, or(parseIdent, or(parseInteger, or(parsePush, attempt(parens(parseLambda))))));
 
 /* takes in stream, outputs parsed items */
 export const parseExprs = many(parseExpr);
\ No newline at end of file