Add show()

src/show.luau

@@ -0,0 +1,18 @@
+if not game then script = require "test/relative-string" end
+
+local switch = require(script.Parent.switch)
+
+local function show<T>(source: () -> any, component: () -> T, fallback: (() -> T)?): () -> T?
+    local function truthy()
+        return not not source()
+    end
+
+    return switch(truthy) {
+        [true] = component,
+        [false] = fallback,
+    }
+end
+
+return show ::
+    (<T>(source: () -> any, component: () -> T) -> () -> T?) &
+    (<T, U>(source: () -> any, component: () -> T, fallback: () -> U) -> () -> (T | U)?)