fix indentation when puking up a linked list

linked lists don't have a measurable length. will use a persistent intangible for debug dumps in the future. `puke` however can be used at the CLI to dump a table. I need to write a `listpuke` variant too

updatedshmup.p8

@@ -9,8 +9,6 @@ game = 1
 win = 2
 lose = 3
 
-debug = {}
-
 function usplit(str)
  return unpack(split(str))
 end
@@ -47,7 +45,9 @@ function mknew(tt, more)
  end
 end
 
-linked_list = {}
+-- intrusive singly-linked list.
+-- cannot be nested!
+linked_list = {is_linked_list=true}
 mknew(linked_list, function(x)
   x.next=nil
   x.tail=x
@@ -251,7 +251,6 @@ end
 
 function _draw()
  drawgame()
- draw_debug()
  if (state == game) fadelvl = -45
  if (state == win) dropshadow("win",50,61,11)
  if (state == lose) dropshadow("fail",48,61,8)
@@ -291,21 +290,44 @@ function fadescreen()
  end
 end
 
-function draw_debug()
- cursor(0,0,7)
- -- uncomment the followingh
- -- to display object counts
---[[
- print("es "..tostr(#eships))
- print("eb "..tostr(#ebullets))
- print("pb "..tostr(#pbullets))
- print("ib "..tostr(#intangibles_bg))
- print("if "..tostr(#intangibles_fg))
- print("v  "..tostr(#events))
-]]
- if (#debug==0) return
- foreach(debug,print)
- debug={}
+-- puke emits a verbose string
+-- describing item, indented to
+-- the specified depth (0 by
+-- default). used for table
+-- debugging. table-type keys
+-- are not legible here
+function puke(item, indent, seen, hidekey)
+ if (type(item) ~= "table") return tostr(item)
+ 
+ seen = seen or {}
+ if (seen[item]) return "<<...>>"
+ seen[item] = true
+ 
+ indent = indent or 0
+ local pfx = "\n"
+ for _=1,indent do
+  pfx ..= " "
+ end
+
+ if item.is_linked_list then
+  local ret,n,xpfx = "linked_list <",0,pfx.." "
+  item:strip(function(x)
+   n += 1
+   ret ..= xpfx..tostr(n)..": "..puke(x, indent+1, seen, "next")
+  end)
+  return ret..pfx..">"
+ end
+
+ local ret = "{"
+ for k, v in pairs(item) do
+  if (k ~= hidekey) ret ..= pfx..tostr(k)..": "..puke(v, indent+1, seen)
+ end
+ return ret..pfx.."}"
+end
+
+-- convenience for debugging
+function puketh(item)
+ printh(puke(item))
 end
 
 function drawgame()