diff --git a/packages/compose/src/juxt.ts b/packages/compose/src/juxt.ts
index 4064f77b1c..a2b6167f0b 100644
--- a/packages/compose/src/juxt.ts
+++ b/packages/compose/src/juxt.ts
@@ -8,7 +8,8 @@ export function juxt<T, A, B, C, D, E>(a: Fn<T, A>, b: Fn<T, B>, c: Fn<T, C>, d:
 export function juxt<T, A, B, C, D, E, F>(a: Fn<T, A>, b: Fn<T, B>, c: Fn<T, C>, d: Fn<T, D>, e: Fn<T, E>, f: Fn<T, F>): Fn<T, [A, B, C, D, E, F]>;
 export function juxt<T, A, B, C, D, E, F, G>(a: Fn<T, A>, b: Fn<T, B>, c: Fn<T, C>, d: Fn<T, D>, e: Fn<T, E>, f: Fn<T, F>, g: Fn<T, G>): Fn<T, [A, B, C, D, E, F, G]>;
 export function juxt<T, A, B, C, D, E, F, G, H>(a: Fn<T, A>, b: Fn<T, B>, c: Fn<T, C>, d: Fn<T, D>, e: Fn<T, E>, f: Fn<T, F>, g: Fn<T, G>, h: Fn<T, H>): Fn<T, [A, B, C, D, E, F, G, H]>;
-export function juxt(...fns: Fn<any, any>[]) {
+export function juxt<T, A, B, C, D, E, F, G, H>(a: Fn<T, A>, b: Fn<T, B>, c: Fn<T, C>, d: Fn<T, D>, e: Fn<T, E>, f: Fn<T, F>, g: Fn<T, G>, h: Fn<T, H>, ...xs: Fn<T, any>[]): Fn<T, any[]>;
+export function juxt<T>(...fns: Fn<any, any>[]) {
     const [a, b, c, d, e, f, g, h] = fns;
     switch (fns.length) {
         case 1:
@@ -28,7 +29,7 @@ export function juxt(...fns: Fn<any, any>[]) {
         case 8:
             return (x) => [a(x), b(x), c(x), d(x), e(x), f(x), g(x), h(x)];
         default:
-            return (x: any) => {
+            return (x: T) => {
                 let res = new Array(fns.length);
                 for (let i = fns.length; --i >= 0;) {
                     res[i] = fns[i](x);
diff --git a/packages/compose/test/delay.ts b/packages/compose/test/delay.ts
new file mode 100644
index 0000000000..a03b216410
--- /dev/null
+++ b/packages/compose/test/delay.ts
@@ -0,0 +1,15 @@
+import { delay } from "../src";
+
+import * as assert from "assert";
+
+describe("delay", () => {
+
+    it("only executes once", () => {
+        let num = 0;
+        const a = delay(() => ++num);
+        assert(!a.isRealized());
+        assert.equal(a.deref(), 1);
+        assert.equal(a.deref(), 1);
+        assert(a.isRealized());
+    });
+});
diff --git a/packages/compose/test/index.ts b/packages/compose/test/index.ts
deleted file mode 100644
index 1a976f7f80..0000000000
--- a/packages/compose/test/index.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-// import * as assert from "assert";
-// import * as compose from "../src/index";
-
-describe("compose", () => {
-    it("tests pending");
-});
diff --git a/packages/compose/test/juxt.ts b/packages/compose/test/juxt.ts
new file mode 100644
index 0000000000..394cdb427b
--- /dev/null
+++ b/packages/compose/test/juxt.ts
@@ -0,0 +1,98 @@
+import { juxt } from "../src";
+
+import * as assert from "assert";
+
+describe("juxt", () => {
+
+    it("2-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x * 10
+        );
+        assert.deepEqual(a(1), [2, 10]);
+    });
+
+    it("3-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x * 10,
+            (x: number) => "id-" + x
+        );
+        assert.deepEqual(a(1), [2, 10, "id-1"]);
+    });
+
+    it("4-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x * 10,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+        );
+        assert.deepEqual(a(1), [2, 10, "id-1", [1, 1]]);
+    });
+
+    it("5-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x * 10,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+            (x: number) => ({ a: x }),
+        );
+        assert.deepEqual(a(1), [2, 10, "id-1", [1, 1], { a: 1 }]);
+    });
+
+    it("6-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x - 1,
+            (x: number) => x * 10,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+            (x: number) => ({ a: x }),
+        );
+        assert.deepEqual(a(1), [2, 0, 10, "id-1", [1, 1], { a: 1 }]);
+    });
+
+    it("7-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x - 1,
+            (x: number) => x * 10,
+            (x: number) => x * 100,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+            (x: number) => ({ a: x }),
+        );
+        assert.deepEqual(a(1), [2, 0, 10, 100, "id-1", [1, 1], { a: 1 }]);
+    });
+
+    it("8-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x - 1,
+            (x: number) => x * 10,
+            (x: number) => x * 100,
+            (x: number) => x * 1000,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+            (x: number) => ({ a: x }),
+        );
+        assert.deepEqual(a(1), [2, 0, 10, 100, 1000, "id-1", [1, 1], { a: 1 }]);
+    });
+
+    it("9-args", () => {
+        const a = juxt(
+            (x: number) => x + 1,
+            (x: number) => x - 1,
+            (x: number) => x * 10,
+            (x: number) => x * 100,
+            (x: number) => x * 1000,
+            (x: number) => x * 10000,
+            (x: number) => "id-" + x,
+            (x: number) => [x, x],
+            (x: number) => ({ a: x }),
+        );
+        assert.deepEqual(a(1), [2, 0, 10, 100, 1000, 10000, "id-1", [1, 1], { a: 1 }]);
+    });
+});
diff --git a/packages/compose/test/partial.ts b/packages/compose/test/partial.ts
new file mode 100644
index 0000000000..9c154f31bf
--- /dev/null
+++ b/packages/compose/test/partial.ts
@@ -0,0 +1,41 @@
+import { partial } from "../src";
+
+import * as assert from "assert";
+
+describe("partial", () => {
+
+    const fn = (a, b, c, d, e, f, g, h, i) => [a, b, c, d, e, f, g, h, i];
+    const res = [0, 1, 2, 3, 4, 5, 6, 7, 8];
+
+    it("1-arg", () => {
+        assert.deepEqual(partial(fn, 0)(1, 2, 3, 4, 5, 6, 7, 8), res);
+    });
+
+    it("2-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1)(2, 3, 4, 5, 6, 7, 8), res);
+    });
+
+    it("3-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2)(3, 4, 5, 6, 7, 8), res);
+    });
+
+    it("4-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2, 3)(4, 5, 6, 7, 8), res);
+    });
+
+    it("5-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2, 3, 4)(5, 6, 7, 8), res);
+    });
+
+    it("6-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2, 3, 4, 5)(6, 7, 8), res);
+    });
+
+    it("7-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2, 3, 4, 5, 6)(7, 8), res);
+    });
+
+    it("8-arg", () => {
+        assert.deepEqual(partial(fn, 0, 1, 2, 3, 4, 5, 6, 7)(8), res);
+    });
+});