diff --git a/generic.js b/generics/generics.js
similarity index 83%
rename from generic.js
rename to generics/generics.js
index 46c136c..304de7d 100644
--- a/generic.js
+++ b/generics/generics.js
@@ -1,6 +1,6 @@
-import { Bool, Int } from "./primitives/symbols.js";
-import { fnType, lsType } from "./type_registry.js";
-import { deepEqual } from "./util.js";
+import { Bool, Int } from "../primitives/symbols.js";
+import { fnType, lsType } from "../type_registry.js";
+import { deepEqual } from "../util.js";
 
 export const makeGeneric = callback => {
   // type variables to make available:
@@ -152,27 +152,3 @@ export const assign = (genFnType, paramType) => {
     type: substitutedOutType,
   };
 }
-
-// a -> Int
-const a_to_Int = makeGeneric(a => fnType({in: a, out: Int}));
-const Bool_to_Int = fnType({in: lsType(Bool), out: Int});
-console.log(matchConcrete(a_to_Int, Bool_to_Int));
-
-// (a -> a) -> b
-const fnType2 = makeGeneric((a,b) => fnType({in: fnType({in: a, out: a}), out: b}));
-// (Bool -> Bool) -> a
-const fnType3 = makeGeneric(a => fnType({in: fnType({in: Bool, out: Bool}), out: a}));
-console.log(matchGeneric(fnType2, fnType3));
-
-// (a -> b) -> [a] -> [b]
-const mapFnType = makeGeneric((a,b) =>
-  fnType({
-    in: fnType({in: a, out: b}),
-    out: fnType({in: lsType(a), out: lsType(b)}),
-  }));
-// a -> a
-const idFnType = makeGeneric(a =>
-  fnType({in: a, out: a}));
-
-// should be: [a] -> [a]
-console.log(assign(mapFnType, idFnType));
diff --git a/generics/generics.test.js b/generics/generics.test.js
new file mode 100644
index 0000000..2930746
--- /dev/null
+++ b/generics/generics.test.js
@@ -0,0 +1,29 @@
+import { Bool, Int } from "../primitives/symbols.js";
+import { fnType, lsType } from "../type_registry.js";
+import { assign, makeGeneric, matchConcrete, matchGeneric } from "./generics.js";
+
+// a -> Int
+const a_to_Int = makeGeneric(a => fnType({in: a, out: Int}));
+// Bool -> Int
+const Bool_to_Int = fnType({in: lsType(Bool), out: Int});
+// should be: Bool -> Int
+console.log(matchConcrete(a_to_Int, Bool_to_Int));
+
+// (a -> a) -> b
+const fnType2 = makeGeneric((a,b) => fnType({in: fnType({in: a, out: a}), out: b}));
+// (Bool -> Bool) -> a
+const fnType3 = makeGeneric(a => fnType({in: fnType({in: Bool, out: Bool}), out: a}));
+// should be: (Bool -> Bool) -> a
+console.log(matchGeneric(fnType2, fnType3));
+
+// (a -> b) -> [a] -> [b]
+const mapFnType = makeGeneric((a,b) =>
+  fnType({
+    in: fnType({in: a, out: b}),
+    out: fnType({in: lsType(a), out: lsType(b)}),
+  }));
+// a -> a
+const idFnType = makeGeneric(a =>
+  fnType({in: a, out: a}));
+// should be: [a] -> [a]
+console.log(assign(mapFnType, idFnType));