reimplement clamp as mid

removes an opportunity to write a bug by swapping low and high

koboldsim/util.go

@@ -25,12 +25,25 @@ func Mean(vals ...float64) float64 {
 	return total / float64(len(vals))
 }
 
-func clamp[T constraints.Ordered](val, low, high T) T {
-	if val < low {
-		return low
+// clamp returns the middle of the three provided values. It doesn't
+// matter which order the values are in. This function is known as `mid` in
+// Pico-8's library, among others. It is usually used to clamp a value to a
+// range, and it doesn't care which order the range is written in.
+func clamp[T constraints.Ordered](a, b, c T) T {
+	if a <= b && a <= c {
+		// `a` is least; mid is lower of `b` or `c`
+		if b <= c {
+			return b
+		}
+		return c
 	}
-	if val > high {
-		return high
+	if a >= b && a >= c {
+		// `a` is most; mid is greater of `b` or `c`
+		if b >= c {
+			return b
+		}
+		return c
 	}
-	return val
+	// `a` is neither most nor least; therefore, `a` is mid
+	return a
 }