1 files changed, 18 insertions, 0 deletions
diff --git a/func.go b/func.go
new file mode 100644
index 0000000..914cb61
--- /dev/null
+++ b/func.go
@@ -0,0 +1,18 @@
+package main
+
+import "math"
+
+// parseFunction returns nil is s is not a valid function.
+func parseFunction(s string) func(Stack) {
+	switch s {
+	case "sin":
+		return sin
+	}
+	return nil
+}
+
+func sin(stack Stack) {
+	if len(stack) > 0 {
+		stack[len(stack)-1] = math.Sin(stack[len(stack)-1])
+	}
+}