diff --git a/new/builtin.mjs b/new/builtin.mjs
index 7b65afd..4819d69 100644
--- a/new/builtin.mjs
+++ b/new/builtin.mjs
@@ -1,7 +1,9 @@
-import {addDefn, addRPNASTDefn, makeFn, cloneElem} from './shiny.mjs';
+import {defnOp, makeOp, defn} from './shiny.mjs';
 import {parseExprs} from './parse.mjs';
 import {tokenize} from './token.mjs';
 
+export let scope = {};
+
 const addRPNDefn = (name, def) => {
     let toks = tokenize(def);
     if (!toks) {
@@ -11,71 +13,110 @@ const addRPNDefn = (name, def) => {
     if (!ast.parsed) {
         throw 'could not load builtin'
     }
-    addRPNASTDefn(name, ast.parsed[0]);
+    scope = defn(name, ast.parsed, scope);
 }
 
-const add = (_, args) => {
-    return [{type:"int", val:args[0] + args[1]}];
+const ASTs = { // should export makeStackElems or eq. to allow for this kind of thing ('ast'?)
+    "true":parseExprs(tokenize("(a b -> a)")).parsed,
+    "false":parseExprs(tokenize("(a b -> b)")).parsed,
 }
 
-const sub = (_, args) => {
-    return [{type:"int", val:args[1] - args[0]}];
-}
-
-const div = (_, args) => {
-    return [{type:"int", val:args[1] / args[0]}];
-}
-
-const mult = (_, args) => {
-    return [{type:"int", val:args[0] * args[1]}];
-}
-
-const pow = (_, args) => {
-    return [{type:"int", val:Math.pow(args[1], args[0])}];
-}
-
-const root = (_, args) => {
-    return [{type:"int", val:Math.sqrt(args[0])}];
-}
-
-const type = (_, args) => {
-    return [{type:"type", val:args[0].type}];
-}
-
-const pair = (_, args) => {
-    return [{type:"pair", val:{fst:args[1], snd:args[0]}}];
-}
-
-const fst = (_, args) => [args[0].fst];
-
-const snd = (_, args) => [args[0].snd];
-
-const eq = (_, args) => {
-    if (args[0].type === args[1].type && args[0].val === args[1].val) {
-        console.log(args[0], args[1])
-        return [{type:"ident", val:"true"}];
-    } else {
-        return [{type:"ident", val:"false"}];
+const assertType = (type) => (elem) => {
+    if (elem.type !== type) {
+        throw 'typeerror'
     }
 }
 
-const tuple = (_, args) => {
+const addDefn = (name, args, fn) => {
+    if (Array.isArray(args)) {
+        const nargs = [...Array(args.length).keys()];
+        const liftFn = (scope) => {
+            let newscope = Object.create(scope);
+            for (let i = 0; i < args.length; i++) {
+                assertType(args[i])(scope[i][0]);
+                newscope[i] = scope[i][0].val;
+            }
+            return fn(newscope);
+        }
+        const op = makeOp(nargs, liftFn);
+        defnOp(name, op);
+    } else {
+        const nargs = [...Array(args).keys()];
+        const liftFn = (scope) => {
+            let newscope = Object.create(scope);
+            for (let i = 0; i < args; i++) {
+                newscope[i] = scope[i][0];
+            }
+            return fn(newscope);
+        }
+        const op = makeOp(nargs, liftFn);
+        defnOp(name, op);
+    }
+}
+
+const add = (args) => {
+    return [{type:"int", val:args[0] + args[1]}];
+}
+
+const sub = (args) => {
+    return [{type:"int", val:args[1] - args[0]}];
+}
+
+const div = (args) => {
+    return [{type:"int", val:args[1] / args[0]}];
+}
+
+const mult = (args) => {
+    return [{type:"int", val:args[0] * args[1]}];
+}
+
+const pow = (args) => {
+    return [{type:"int", val:Math.pow(args[1], args[0])}];
+}
+
+const root = (args) => {
+    return [{type:"int", val:Math.sqrt(args[0])}];
+}
+
+const type = (args) => {
+    return [{type:"type", val:args[0].type}];
+}
+
+const pair = (args) => {
+    return [{type:"pair", val:{fst:args[0], snd:args[1]}}];
+}
+
+const fst = (args) => [args[0].fst];
+
+const snd = (args) => [args[0].snd];
+
+const eq = (args) => {
+    args = defn("true", ASTs["true"], args);
+    args = defn("false", ASTs["false"], args);
+    if (args[0].type === args[1].type && args[0].val === args[1].val) {
+        console.log(args[0], args[1])
+        return args["true"];
+    } else {
+        return args["false"];
+    }
+}
+
+const tuple = (args) => {
     return [makeFn(args[0], (_, args) => {return [{type:"tuple", val:args}]})];
 }
 
-const index = (_, args) => {
-    return [args[1][args[0]]];
+const index = (args) => {
+    return [args[0][args[1]]];
 }
 
-const len = (_, args) => {
+const len = (args) => {
     return [{type:"int", val:args[0].length}];
 }
 
-const coerce = (_, args) => {
+const coerce = (args) => {
     if (args[0].type === "type") {
-        let o = cloneElem(args[1]);
-        o.type = args[0].val;
-        return o;
+        let o = {type:args[1].val, val:args[0].val};
+        return [o];
     } else {
         throw 'typeerror'
     }
@@ -93,7 +134,7 @@ addDefn("pair", 2, pair);
 addDefn("fst", ["pair"], fst);
 addDefn("snd", ["pair"], snd);
 addDefn("tuple", ["int"], tuple);
-addDefn("!!", ["int", "tuple"], index);
+addDefn("!!", ["tuple", "int"], index);
 addDefn("len", ["tuple"], len);
 addDefn("unsafeCoerce", 2, coerce);
 //addRPNDefn("unit", "(-> 0 arr)");
diff --git a/new/main.js b/new/main.js
index 9ba0fd3..c233e00 100644
--- a/new/main.js
+++ b/new/main.js
@@ -1,7 +1,7 @@
 import {execRPN} from './shiny.mjs';
 import {parseExprs} from './parse.mjs';
 import {tokenize} from './token.mjs';
-//import './builtin.mjs';
+import {scope} from './builtin.mjs';
 
 const inbox = document.getElementById("inbox")
 const outbox = document.getElementById("outbox")
@@ -19,7 +19,7 @@ const show = (elem) => {
     } else if (elem.type === "array") {
         return "[" + prettyprint(elem.val) + "]"
     } else if (elem.val) {
-        return "(" + elem.type + ": " + elem.val + ")"
+        return "(" + elem.val + ": " + elem.type + ")"
     } else {
         return elem.type
     }
@@ -48,11 +48,11 @@ submit.onclick = (event) => {
         outbox.innerHTML = "incorrect syntax somewhere";
         return;
     }
-    let out = execRPN({}, ast.parsed);
+    let out = execRPN(scope, ast.parsed);
     if (!out) {
         outbox.innerHTML = "failed to execute";
         return;
     }
-    //console.log(out.stacks);
+    console.log(out);
     outbox.innerHTML = prettyprint(out.stacks[0]);
 }
\ No newline at end of file
diff --git a/new/shiny.mjs b/new/shiny.mjs
index 89ec0ef..d059b5e 100644
--- a/new/shiny.mjs
+++ b/new/shiny.mjs
@@ -17,6 +17,8 @@ TYPE        VAL
 
 exported functionality:
 defnOp(name, function) - define a built-in operator
+defn(name, ins, scope) - extend scope with AST
+makeOp(name, args, fn) - lift a function to an operator
 evalRPN(scope, ast)
 */
 
@@ -26,12 +28,25 @@ export const defnOp = (name, data) => {
     builtins[name] = data;
 }
 
+export const defn = (name, ins, scope) => {
+    let defscope = Object.create(scope);
+    let fnForm = {type:"closure", val:{scope:defscope, args:[], defn:{type:"ins", ins:ins}}};
+    defscope[name] = [fnForm];
+    let out = execRPN(defscope, ins);
+    defscope[name] = out.stacks[0];
+    return defscope;
+}
+
+export const makeOp = (args, fn) => {
+    return [{type:"closure", val:{scope:{}, args:args, defn:{type:"builtin", fn:fn}}}];
+}
+
 const lookup = (name, scope) => {
     let n = scope[name];
     if (n) {
         return n;
     }
-    n = builtins[n];
+    n = builtins[name];
     if (n) {
         return n;
     }
@@ -100,16 +115,7 @@ const doIns = (ins, state) => {
     if (ins.type === "push") {
         state.stacks[state.stacks.length-1] = state.stacks[state.stacks.length-1].concat(makeStackElems(ins.elem, state));
     } else if (ins.type === "defn") {
-        // initialize definition scope
-        let defscope = Object.create(state.scopes[state.scopes.length-1]);
-        // parse into closure for definition's scope (to allow for recursion)
-        let fnForm = {type:"closure", val:{scope:defscope, args:[], defn:{type:"ins", ins:ins.defn}}};
-        // add fnForm to definition scope
-        defscope[ins.ident] = [fnForm];
-        // evaluate fnForm
-        let out = execRPN(defscope, ins.defn);
-        defscope[ins.ident] = out.stacks[0];
-        state.scopes[state.scopes.length-1] = defscope;
+        state.scopes[state.scopes.length-1] = defn(ins.ident, ins.defn, state.scopes[state.scopes.length-1]);
     } else {
         applyMany(makeStackElems(ins, state), state);
     }
@@ -129,7 +135,11 @@ const step = (state) => {
     } else {
         let ins = state.calls[state.calls.length-1][0];
         state.calls[state.calls.length-1] = state.calls[state.calls.length-1].slice(1);
-        doIns(ins, state);
+        try {
+            doIns(ins, state);
+        } catch (error) {
+            throw error + ' while executing "' + ins.val + '"'
+        }
     }
 }