diff --git a/main.js b/main.js
index b055154..4dc5327 100644
--- a/main.js
+++ b/main.js
@@ -1,61 +1,33 @@
 import { select } from '@inquirer/prompts';
 import { ModulePoint } from "./lib/point.js";
-import { DefaultMap, pretty } from './util.js';
+import { DefaultMap, pretty, prettyT } from './util.js';
 import { symbolFunction } from './structures/types.js';
 import { ModuleStd } from './stdlib.js';
+import { Type } from './type.js';
 
 class Context {
   constructor(mod) {
-    this.functionsFrom = new DefaultMap(() => []); // type to outgoing function
-    this.functionsTo = new DefaultMap(() => []); // type to incoming function
-    this.types = new DefaultMap(() => []); // instance to type
-    this.instances = new DefaultMap(() => []); // type to instance
+    this.types = new DefaultMap(() => new Set()); // instance to type
+    this.instances = new DefaultMap(() => new Set()); // type to instance
+
+    this.functionsFrom = new DefaultMap(() => new Set()); // type to outgoing function
+    this.functionsTo = new DefaultMap(() => new Set()); // type to incoming function
 
     for (const {i, t} of mod.l) {
-      this.types.getdefault(i, true).push(t);
-      this.instances.getdefault(t, true).push(i);
+      this.types.getdefault(i, true).add(t);
+      this.instances.getdefault(t, true).add(i);
     }
 
-    for (const [i, types] of this.instances.m.entries()) {
-      for (const t of types) {
-        if (t.symbol === symbolFunction) {
-          // 'i' is a function
-          this.functionsFrom.getdefault(t.params[0], true).push(i);
-          this.functionsFrom.getdefault(t.params[1], true).push(i);
+    for (const t of this.instances.m.keys()) {
+      if (t.symbol === symbolFunction) {
+        // 't' is a function signature
+        for (const fn of this.instances.getdefault(t)) {
+          this.functionsFrom.getdefault(t.params[0], true).add(fn);
+          this.functionsTo  .getdefault(t.params[1], true).add(fn);
         }
       }
-    }
+    }    
   }
-
-    // const callFunctionOnEveryValue = (fn, fnType, indent=1) => {
-    //   const inType = getIn(fnType);
-    //   const outType = getOut(fnType);
-    //   console.log();
-    //   if (fn.name !== "") {
-    //   console.log("--".repeat(indent), fn, ':', fnType);
-    //   }
-    //   for (const i of this.instances.getdefault(inType)) {
-    //     try {
-    //       const result = fn(i);
-    //       console.log("--".repeat(indent+1), i, '->', result);
-    //       if (this.types.getdefault(outType).includes(Function)) {
-    //         if (indent < 5) {
-    //           callFunctionOnEveryValue(result, outType, indent+2);
-    //         }
-    //       }
-    //     } catch (e) {
-    //       console.log("--".repeat(indent+1), i, `-> (exception: ${e})`);
-    //     }
-    //   }
-    // }
-    // for (const fntypes of this.functionsFrom.m.values()) {
-    //   for (const fntype of fntypes) {
-    //     for (const fn of this.instances.getdefault(fntype)) {
-    //       callFunctionOnEveryValue(fn, fntype);
-    //     }
-    //   }
-    // }
-  // }
 }
 
 const ctx = new Context({l:[
@@ -63,49 +35,231 @@ const ctx = new Context({l:[
   ...ModulePoint.l,
 ]});
 
-const makeChoice = ([i, t]) => {
-  return {
-    value: {i, t: t[0]},
-    name: pretty(i),
-    description: ` :: ${pretty(t[0])}`,
-    short: `${pretty(i)} :: ${pretty(t[0])}`,
-  };
+
+
+const prettyIT = ({i, t}) => ({
+  strI: isType(i) ? prettyT(i) : pretty(i),
+  strT: prettyT(t),
+})
+
+const toChoices = ([i, types]) => {
+  return [...types].map(t => {
+    const {strI, strT} = prettyIT({i, t});
+    return {
+      value: {i, t},
+      name: strI,
+      description: ` :: ${strT}`,
+      short: `${strI} :: ${strT}`,
+    };
+  });
 }
 
-let {i,t} = await select({
-  message: "Choose value:",
-  choices: [...ctx.types.entries()].map(makeChoice),
-});
+const isType = i => ctx.types.getdefault(i).has(Type);
 
-while (true) {
-  let fn, fnType;
-  if (ctx.types.getdefault(t).includes(Function)) {
-    fn = i;
-    fnType = t;
-    const s = await select({
-      message: "Select input for function:",
-      choices: ctx.instances.getdefault(getIn(t))
-        .map(i => [i, ctx.types.getdefault(i)])
-        .map(makeChoice),
-    });
-    i = s.i;
-    t = s.t;
+async function topPrompt() {
+  const action = await select({
+    message: "What do you want to do?",
+    choices: [
+      "list all types",
+      "list all functions",
+      "list all",
+    ],
+  });
+  if (action === "list all types") {
+    await listAllTypes();
   }
-  else{
-    fn = await select({
-      message: "Choose function:",
-      choices: [...ctx.functionsFrom.getdefault(t).map(fn => ({
-          value: fn,
-          name: pretty(fn),
-          description: `${pretty(fn)} :: ${pretty(ctx.types.getdefault(fn)[0])}`,
-          short: `${pretty(fn)} :: ${pretty(ctx.types.getdefault(fn)[0])}`,
-        })
-      )],
-    });
-    fnType = ctx.types.getdefault(fn)[0];
+  if (action === "list all") {
+    await listAllInstances();
   }
+  return topPrompt();
+}
+
+async function listAllTypes() {
+  const choice = await select({
+    message: "select type:",
+    choices: [
+      "(go back)",
+      ...[...ctx.instances.m.keys()].map(t => ({
+        value: t,
+        name: prettyT(t),
+      })),
+    ]
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  await typeOptions(choice);
+  return listAllTypes();
+}
+
+async function typeOptions(t) {
+  const choice = await select({
+    message: `actions for type ${prettyT(t)} :: Type`,
+    choices: [
+      "(go back)",
+      "list instances",
+      "list outgoing functions",
+      "list incoming functions",
+      "treat as instance",
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  else if (choice === "list instances") {
+    await listInstances(t);
+  }
+  else if (choice === "treat as instance") {
+    await instanceOptions(t, Type)
+  }
+  else {
+    console.log("unimplemented:", choice);
+  }
+  return typeOptions(t);
+}
+
+async function listAllInstances() {
+  const choice = await select({
+    message: `all instances:`,
+    choices: [
+      "(go back)",
+      ... [...ctx.types.m.keys()].flatMap(i => toChoices([i, ctx.types.getdefault(i)])),
+    ],
+  })
+  if (choice === "(go back)") {
+    return;
+  }
+  return instanceOrTypeOrFnOptions(choice);
+}
+
+async function instanceOrTypeOrFnOptions({i, t}) {
+  if (t.symbol === symbolFunction) {
+    return functionOptions(i, t);
+  }
+  if (isType(i)) {
+    return typeOptions(i);
+  }
+  return instanceOptions(i,t);
+}
+
+async function listInstances(t) {
+  const choice = await select({
+    message: `instances of ${prettyT(t)}:`,
+    choices: [
+      "(go back)",
+      ... [...ctx.instances.getdefault(t)].flatMap(i => toChoices([i, [t]])),
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  return instanceOrTypeOrFnOptions(choice);
+}
+
+async function listTypes(i) {
+  const {strI} = prettyIT({i,t:Type});
+  const choice = await select({
+    message: `type(s) of ${strI}:`,
+    choices: [
+      "(go back)",
+      ... [...ctx.types.getdefault(i)].flatMap(t => toChoices([t, ctx.types.getdefault(t)])),
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  const {i: chosenType} = choice;
+  await typeOptions(chosenType);
+  return listTypes(i);
+}
+
+async function functionOptions(fn, fnT) {
+  const {strI, strT} = prettyIT({i: fn, t: fnT});
+  const choice = await select({
+    message: `actions for function ${strI} :: ${strT}`,
+    choices: [
+      "(go back)",
+      "call",
+      "treat as instance",
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  if (choice === "call") {
+    await callFunction(fn, fnT);
+  }
+  if (choice === "treat as instance") {
+    await instanceOptions(fn, fnT);
+  }
+  return functionOptions(fn, fnT);
+}
+
+async function callFunction(fn, fnT) {
+  const {strI, strT} = prettyIT({i: fn, t: fnT});
+  const inType = fnT.params[0];
+  const choice = await select({
+    message: `select parameter for function ${strI} :: ${strT}`,
+    choices: [
+      "(go back)",
+      ... [...ctx.instances.getdefault(inType)].flatMap(i => toChoices([i, ctx.types.getdefault(i)])),
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  const {i, t} = choice;
+  await apply(i, fn, fnT);
+  return callFunction(fn, fnT);
+}
+
+async function instanceOptions(i,t) {
+  const {strI, strT} = prettyIT({i,t});
+  const choice = await select({
+    message: `actions for instance ${strI} :: ${strT}`,
+    choices: [
+      "(go back)",
+      "transform",
+      "list type(s)",
+    ]
+  })
+  if (choice === "(go back)") {
+    return;
+  }
+  if (choice === "transform") {
+    await transform(i, t)
+  }
+  if (choice === "list type(s)") {
+    await listTypes(i);
+  }
+  return await instanceOptions(i,t);
+}
+
+async function transform(i, t) {
+  const {strI, strT} = prettyIT({i, t});
+  console.log(ctx.functionsFrom.getdefault(t));
+  
+  const choice = await select({
+    message: `choose transformation to perform on ${strI} :: ${strT}`,
+    choices: [
+      "(go back)",
+      ... [...ctx.functionsFrom.getdefault(t)].flatMap(fn => toChoices([fn, ctx.types.getdefault(fn)])),
+    ],
+  });
+  if (choice === "(go back)") {
+    return;
+  }
+  const {i:fn,t:fnT} = choice;
+  await apply(i, fn, fnT);
+  return transform(i, t);
+}
+
+async function apply(i, fn, fnT) {
   const result = fn(i);
-  t = getOut(fnType);
-  console.log("result =", result, "::", t);
-  i = result;
+  const resultType = fnT.params[1];
+  const {strI: strResult, strT: strResultType} = prettyIT({i: result, t: resultType});
+  console.log(`result = ${strResult} :: ${strResultType}`);
+  return instanceOrTypeOrFnOptions({i: result, t: resultType});
 }
+
+topPrompt();
diff --git a/primitives/char.js b/primitives/char.js
index f84afc5..1bbc9d2 100644
--- a/primitives/char.js
+++ b/primitives/char.js
@@ -7,5 +7,10 @@ const eq = x => y => x === y;
 export const ModuleChar = {l:[
   {i: Char, t: Type},
 
-  ...typedFnType(eq, fnType => fnType({in: Char, out: fnType({in: Char, out: Bool})})),
+  ...typedFnType(eq, fnType =>
+    fnType
+      (Char)
+      (fnType
+        (Char)
+        (Bool))),
 ]};
diff --git a/primitives/types.js b/primitives/types.js
index bb9f0b0..adb5d3e 100644
--- a/primitives/types.js
+++ b/primitives/types.js
@@ -1,8 +1,7 @@
 // to break up dependency cycles, primitive types are defined in their own JS module
 
-
 export const Int    = { symbol: Symbol('Int')   , params: [] };
 export const Bool   = { symbol: Symbol('Bool')  , params: [] };
 export const Double = { symbol: Symbol('Double'), params: [] };
 export const Byte   = { symbol: Symbol('Byte')  , params: [] };
-export const Char   = { symbol: Symbol('Char')  , params: [] };// Wrapper around function below.
+export const Char   = { symbol: Symbol('Char')  , params: [] };
diff --git a/structures/function.js b/structures/function.js
index 00a93f2..bfef251 100644
--- a/structures/function.js
+++ b/structures/function.js
@@ -2,6 +2,7 @@ import { Type } from "../type.js";
 import { typedFnType } from "./types.js";
 import { fnType } from "./types.js";
 
+// export const pprintFn = fnT => ``
 
 export const ModuleFunction = {l:[
   // binary type constructor: Type -> Type -> Type
diff --git a/structures/types.js b/structures/types.js
index bbff7b4..1aefe60 100644
--- a/structures/types.js
+++ b/structures/types.js
@@ -1,5 +1,6 @@
 // to break up dependency cycles, type constructors are defined in their own JS module
 
+import { Type } from "../type.js";
 import { DefaultMap } from "../util.js";
 
 
@@ -36,14 +37,14 @@ export const typedFnType2 = callback => {
   const t = callback(wrappedFnType); // force evaluation
   return [
     t,
-    fnTs.map(fnT => ({ i: fnT, t: Function })),
+    fnTs.map(fnT => ({ i: fnT, t: Type })),
   ];
 };
 
 
 // Sum type
 
-const symbolSum = Symbol("Sum");
+export const symbolSum = Symbol("Sum");
 const sumTypeRegistry = new DefaultMap(leftType => new DefaultMap(rightType => ({
   symbol: symbolSum,
   params: [leftType, rightType],
@@ -54,7 +55,7 @@ export const sumType = leftType => rightType => sumTypeRegistry.getdefault(leftT
 
 // Product type
 
-const symbolProduct = Symbol("Product");
+export const symbolProduct = Symbol("Product");
 const productTypeRegistry = new DefaultMap(leftType => new DefaultMap(rightType => ({
   symbol: symbolProduct,
   params: [leftType, rightType],
@@ -65,7 +66,7 @@ export const prodType = leftType => rightType => productTypeRegistry.getdefault(
 
 // List type
 
-const symbolList = Symbol('List');
+export const symbolList = Symbol('List');
 const listTypeRegistry = new DefaultMap(elementType => ({
   symbol: symbolList,
   params: [elementType],
diff --git a/typeclasses/eq.js b/typeclasses/eq.js
index 4b9482f..9256e6a 100644
--- a/typeclasses/eq.js
+++ b/typeclasses/eq.js
@@ -8,19 +8,21 @@ import { eqDictType } from "./eq_type";
 export const getEq = numDict => numDict.eq;
 
 export const ModuleEq = {l:[
-  ...typedFnType(eqDictType, fnType => fnType({in: Type, out: Type})),
+  // type constructor: Type -> Type
+  ...typedFnType(eqDictType, fnType => fnType(Type)(Type)),
 
-  ...typedFnType(getEq, fnType => makeGeneric(a =>
-    fnType({
-      in: eqDictType(a),
-      out: fnType({
-        in: a,
-        out: fnType({
-          in: a,
-          out: Bool,
-        }),
-      }),
-    }))),
+  // (EqDict a) -> a -> a -> Bool
+  ...typedFnType(getEq, fnType =>
+    makeGeneric(a =>
+      fnType
+        (eqDictType(a))
+        (fnType
+          (a)
+          (fnType
+            (a)
+            (Bool)
+          )
+        ))),
 ]};
 
 // all our data (and types) are encoded such that we can test equality the same way:
diff --git a/typeclasses/eq_type.js b/typeclasses/eq_type.js
index 09e5614..5055d66 100644
--- a/typeclasses/eq_type.js
+++ b/typeclasses/eq_type.js
@@ -1,4 +1,8 @@
 import { DefaultMap } from "../util.js";
 
-const eqDictTypeRegistry = new DefaultMap(a => ({ eqDict: a }));
+const eqDictSymbol = Symbol('EqDict');
+const eqDictTypeRegistry = new DefaultMap(a => ({
+  symbol: eqDictSymbol,
+  params: [a],
+}));
 export const eqDictType = a => eqDictTypeRegistry.getdefault(a, true);
diff --git a/typeclasses/num_type.js b/typeclasses/num_type.js
index 54537c9..989040e 100644
--- a/typeclasses/num_type.js
+++ b/typeclasses/num_type.js
@@ -1,4 +1,8 @@
 import { DefaultMap } from "../util.js";
 
-const numDictTypeRegistry = new DefaultMap(a => ({ numDict: a }));
+const numDictSymbol = Symbol("NumDict");
+const numDictTypeRegistry = new DefaultMap(a => ({
+  symbol: numDictSymbol,
+  params: [a],
+}));
 export const numDictType = a => numDictTypeRegistry.getdefault(a, true);
diff --git a/util.js b/util.js
index 4fd92fb..6146ad8 100644
--- a/util.js
+++ b/util.js
@@ -47,7 +47,30 @@ export class DefaultMap {
 
 
 import { inspect } from 'node:util';
+import { symbolFunction, symbolList, symbolProduct, symbolSum } from './structures/types.js';
 
 export function pretty(obj) {
   return inspect(obj, {colors: true, depth: null});
-}
\ No newline at end of file
+}
+
+export function prettyT(type) {
+  if (type.typeVars) {
+    return `∀${[...type.typeVars].map(prettyT).join(", ")}: ${prettyT(type.type)}`;
+  }
+  if (type.symbol === symbolFunction) {
+    return `${prettyT(type.params[0])} -> ${prettyT(type.params[1])}`;
+  }
+  if (type.symbol === symbolList) {
+    return `[${prettyT(type.params[0])}]`;
+  }
+  if (type.symbol === symbolProduct) {
+    return `(${prettyT(type.params[0])}, ${prettyT(type.params[1])})`;
+  }
+  if (type.symbol === symbolSum) {
+    return `(${prettyT(type.params[0])} | ${prettyT(type.params[1])})`;
+  }
+  if (type.params.length === 0) {
+    return type.symbol.description;
+  }
+  return `${type.symbol.description}(${type.params.map(prettyT).join(", ")})`;
+}