Penalize less for age (#198)

And explain why questions aren't ordered by votes

client/src/App.svelte

@@ -81,6 +81,12 @@
 {#if $event}
 	<main class="mx-auto my-4 max-w-4xl px-4">
 		<List />
+		<div class="mt-4 text-center text-slate-400">
+			Questions are ordered by <a
+				class="hover:text-black"
+				href="https://www.evanmiller.org/ranking-news-items-with-upvotes.html">votes over time</a
+			>.
+		</div>
 		<div class="mt-4 text-center text-slate-400">
 			( made on <a class="hover:text-black" href="https://github.com/jonhoo/wewerewondering"
 				>github</a

server/src/list.rs

@@ -224,10 +224,19 @@ async fn list_inner(
                     )
                     .unwrap_or(Duration::ZERO)
                     .as_secs()
+                    // in minutes so questions don't jump around quite as much
                     / 60;
+                // +1 so that first minute questions don't get inf scores (for the ln)
                 let dt = dt_in_minutes_rounded_down + 1;
+                // +1 again to avoid NaN scores for first-minute questions (for / (1 - e^0)).
+                let dt = dt + 1;
+                // ln so that stories get less penalized for age over time
+                // after all, this is Q&A, not minute-to-minute hot news
+                let dt = (dt as f64).ln();
                 let votes = q["votes"].as_u64().expect("votes is a number") as f64;
-                let exp = (-1. * dt as f64).exp();
+                // max so that even if vote count somehow got to 0, count it as 1
+                let votes = votes.max(1.);
+                let exp = (-1. * dt as f64).exp_m1() + 1.;
                 Score(exp * votes / (1. - exp))
             };
             questions.sort_by_cached_key(|q| std::cmp::Reverse(score(q)));