Compiler eating memory infinitely

[s5bug]

I've tried to minimize this and I just can't seem to get the same behavior when I do.

The project is at https://gitdab.com/s/ootAI. I suspect that the equipment record in oot/equipment.ml is the problem.

If equipment: u16 is replaced with equipment: equipment here (permalink), the compiler gets stuck and eats up all my memory.

[s5bug]

As of commit 4852cffa0a, the compiler freezes, but applying this diff makes the compiler work properly.

diff --git a/oot/item.ml b/oot/item.ml
index d077ea2..b39ee47 100644
--- a/oot/item.ml
+++ b/oot/item.ml
@@ -7,7 +7,6 @@ open import "../mem/int.ml"
 type item =
 | DekuSticks
 | NoItem
-| UnknownItem of int

 instance decode item begin
   let decode addr =
@@ -15,12 +14,10 @@ instance decode item begin
     match code with
     | 0 -> DekuSticks
     | 255 -> NoItem
-    | x -> UnknownItem x
 end

 instance show item begin
   let show = function
   | DekuSticks -> "Deku Sticks"
   | NoItem -> "No Item"
-  | UnknownItem x -> "Unknown Item " ^ (show x)
 end

What is going on?

[s5bug]

I've been told to note that the following diff:

diff --git a/oot/item_equips.ml b/oot/item_equips.ml
index a4374e3..cceb4e2 100644
--- a/oot/item_equips.ml
+++ b/oot/item_equips.ml
@@ -3,8 +3,9 @@ open import "../pretty.ml"
 open import "../mem/decode.ml"
 open import "../mem/int.ml"
 open import "./item.ml"
+open import "./equipment.ml"
 
-type item_equips = ItemEquips of {
+type item_equips_ 'a = ItemEquips of {
   button_item_b: item,
   button_item_c_left: item,
   button_item_c_down: item,
@@ -12,10 +13,11 @@ type item_equips = ItemEquips of {
   button_slot_c_left: u8,
   button_slot_c_down: u8,
   button_slot_c_right: u8,
-  equipment: u16
+  equipment: 'a
 }
+type item_equips <- item_equips_ equipment
 
-instance decode item_equips begin
+instance decode 'a => decode (item_equips_ 'a) begin
   let decode addr = ItemEquips {
     button_item_b = decode (addr + 0x00),
     button_item_c_left = decode (addr + 0x01),
@@ -28,7 +30,7 @@ instance decode item_equips begin
   }
 end
 
-instance prettyrecord item_equips begin
+instance pretty 'a => prettyrecord (item_equips_ 'a) begin
   let name _ = "ItemEquips"
   let fields (ItemEquips x) =
     [
@@ -39,10 +41,10 @@ instance prettyrecord item_equips begin
       ("button_slot_c_left", S x.button_slot_c_left),
       ("button_slot_c_down", S x.button_slot_c_down),
       ("button_slot_c_right", S x.button_slot_c_right),
-      ("equipment", S x.equipment)
+      ("equipment", P x.equipment)
     ]
 end
 
-instance pretty item_equips begin
+instance pretty 'a => pretty (item_equips_ 'a) begin
   let pretty = pretty_from_record
 end

still makes the compiler freeze, even when patching in the above diff.

[SquidDev]

It's the pattern matcher, because of course it is.

When Lower your guards came out (says August 2020, but this was much earlier) @plt-hokusai and I discussed switching to it. Then lockdown happened and I graduated, and um ... it never materialised.

Guess now is as good a time as any!