diff --git a/index.d.ts b/index.d.ts
index 904d28c..67ce8ee 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -334,6 +334,10 @@ export function pretty(obj: any): any;
 
 export function prettyT(type: any): any;
 
+export function prettyU(unification: any): string;
+
+export function prettyST(setOfTypes: any): string;
+
 export function prodType(typeParam: any): any;
 
 export function recomputeTypeVars(types: any, skip: number): any;
diff --git a/lib/generics/low_level.js b/lib/generics/low_level.js
index 414e8b9..d313060 100644
--- a/lib/generics/low_level.js
+++ b/lib/generics/low_level.js
@@ -142,9 +142,9 @@ export const reduceUnification = (unif) => {
 };
 
 // For debugging
-const prettyU = unif => {
+export const prettyU = unif => {
   return `{${[...unif].map(([symbol, types]) => `${getHumanReadableName(symbol)} => ${prettyST(types)}`).join(', ')}}`;
 };
-const prettyST = st => {
+export const prettyST = st => {
   return `(${st.keys().map(prettyT).join(',')})`;
 };