propagators/conditional.test -- fix switcher -- should not take outpu…

…t as arg

TODO.md

@@ -4,8 +4,6 @@
 
 > https://github.com/cicada-lang/propagator/issues/4
 
-propagators/conditional.test
-
 propagators/constant.test
 propagators/boolean
 propagators/boolean.test

src/propagators/conditional.test.ts

@@ -0,0 +1,15 @@
+import test from "node:test"
+import { patch } from "../cell/index.js"
+import { run } from "../scheduler/index.js"
+import { conditional } from "./conditional.js"
+
+test("propagators / conditional", async () => {
+  {
+    const [control, ifTrue, ifFalse, output] = conditional()
+    patch(control, true)
+    patch(ifFalse, 0)
+    patch(ifTrue, 1)
+    await run()
+    assert(output.content === 1)
+  }
+})

src/propagators/switcher.ts

@@ -1,7 +1,7 @@
+import { nothing } from "../nothing/Nothing.js"
 import { definePrimitive } from "../propagator/index.js"
 
 // For `switch` is preserved by JavaScript.
-export const switcher = definePrimitive(3, (control, input, output) => {
-  if (control) return input
-  else return output
-})
+export const switcher = definePrimitive(3, (control, input) =>
+  control ? input : nothing,
+)