Allow error messages in parsing (for debugging)

And fix an off-by-one in day 5

1 files changed, 1 insertions, 4 deletions

diff --git a/Main.lean b/Main.lean
index b6d152e..1ad3933 100644
--- a/Main.lean
+++ b/Main.lean
@@ -9,10 +9,7 @@ open DayPart
 
 def try_run_day_part (day : Days) (part : Parts) (data : String) : IO String :=
   let impl : {ι : Type} →  (d : Days) → (p : Parts) → String → [Parse d (ι := ι)] → [Part d p (ι := ι)] → IO String := λ day part data ↦ do
-    let instructions ← if let some instructions := Parse.parse day data then
-      pure instructions
-    else
-      throw $ IO.userError "Failed to parse input file."
+    let instructions ← IO.ofExcept $ Parse.parse day data
     if let some result := (Part.run day part instructions).map ToString.toString then
       pure result
     else