diff --git a/docs/langs/explicit-substitution/reduce/lookup.cic b/docs/langs/explicit-substitution/reduce/lookup.cic
index 46b7a18f..61e48854 100644
--- a/docs/langs/explicit-substitution/reduce/lookup.cic
+++ b/docs/langs/explicit-substitution/reduce/lookup.cic
@@ -3,11 +3,11 @@ import { Binding, Exp } from "../exp/index.cic"
 export function lookup(
   name: string,
   bindings: List(Binding),
-): Optional(Exp) {
+): Maybe(Exp) {
   let found = listFind(
     listReverse(bindings),
     (binding) => stringEqual(binding.name, name)
   )
 
-  return optionalMap(found, (binding) => binding.exp)
+  return maybeMap(found, (binding) => binding.exp)
 }
diff --git a/docs/langs/explicit-substitution/reduce/reduce.cic b/docs/langs/explicit-substitution/reduce/reduce.cic
index b6f6fc85..43e8fb87 100644
--- a/docs/langs/explicit-substitution/reduce/reduce.cic
+++ b/docs/langs/explicit-substitution/reduce/reduce.cic
@@ -8,9 +8,9 @@ import { substitute } from "./substitute.cic"
 
 export function reduce(mod: Mod, exp: Exp): Exp {
   match (exp) {
-    case Exp::var(name) => {
-      let defintion = modFind(mod, name)
-      return if isNone(defintion) then exp else reduce(mod, defintion.exp)
+    case Exp::var(name) => match (modFind(mod, name)) {
+      case Maybe::just(defintion) => exp
+      case Maybe::nothing() => reduce(mod, defintion.exp)
     }
 
     case Exp::fn(name, ret) =>
diff --git a/docs/langs/explicit-substitution/reduce/substitute.cic b/docs/langs/explicit-substitution/reduce/substitute.cic
index e73eca59..b87e9446 100644
--- a/docs/langs/explicit-substitution/reduce/substitute.cic
+++ b/docs/langs/explicit-substitution/reduce/substitute.cic
@@ -7,10 +7,10 @@ export function substitute(
   body: Exp,
 ): Exp {
   match (body) {
-    case Exp::Var(name) => {
-      let found = lookup(name, bindings)
-      return if isNone(found) then body else found
-    }
+    case Exp::Var(name) => match (lookup(name, bindings)) {
+       case Maybe::just(exp) => exp
+       case Maybe::nothing() => body
+     }
 
     case Exp::fn(name, ret) => {
       let freshName = freshen(name)