all: initial interpreter code (#12605)

examples/fibonacci.v

@@ -1,18 +1,17 @@
 // This program displays the fibonacci sequence
-// import os
+import os
 
 fn main() {
 	// Check for user input
-	// if os.args.len != 2 {
-	//		println('usage: fibonacci [rank]')
+	if os.args.len != 2 {
+		println('usage: fibonacci [rank]')
 
-	// Exit
-	//		return
-	//	}
+		return
+	}
 
 	// Parse first argument and cast it to int
-	//	stop := os.args[1].int()
-	stop := 23
+
+	stop := os.args[1].int()
 	// Can only calculate correctly until rank 92
 	if stop > 92 {
 		println('rank must be 92 or less')
@@ -20,9 +19,9 @@ fn main() {
 	}
 
 	// Three consecutive terms of the sequence
-	mut a := 0
-	mut b := 0
-	mut c := 1
+	mut a := i64(0)
+	mut b := i64(0)
+	mut c := i64(1)
 	println(a + c + c)
 	for _ in 0 .. stop {
 		// Set a and b to the next term