Initial working version.

nomsu.lua

@@ -69,7 +69,8 @@ local _list_0 = {
   "Number",
   "Word",
   "Var",
-  "Comment"
+  "Comment",
+  "IndexChain"
 }
 for _index_0 = 1, #_list_0 do
   local t = _list_0[_index_0]
@@ -185,7 +186,7 @@ setmetatable(NOMSU_DEFS, {
     make_node = function(start, value, stop)
       node_id = node_id + 1
       if type(value) == 'table' then
-        error(value)
+        error("Not a tuple: " .. tostring(repr(value)))
       end
       local node = Types[key](node_id, value)
       lpeg.userdata.tree_metadata[node] = {
@@ -966,6 +967,24 @@ do
         return {
           expr = repr(tree.value)
         }
+      elseif "IndexChain" == _exp_0 then
+        local items = { }
+        for i, item in ipairs(tree.value) do
+          local lua = self:tree_to_lua(item)
+          if not (lua.expr) then
+            local line = self:get_line_number(item)
+            local src = self:get_source_code(item)
+            error(tostring(line) .. ": Cannot index " .. tostring(colored.yellow(src)) .. ", since it's not an expression.", 0)
+          end
+          if i == 1 then
+            insert(items, "(" .. tostring(lua.expr) .. ")")
+          else
+            insert(items, "[ " .. tostring(lua.expr) .. "]")
+          end
+        end
+        return {
+          expr = concat(items, "")
+        }
       elseif "Block" == _exp_0 then
         local lua_bits = { }
         local locals = { }
@@ -1798,6 +1817,7 @@ if arg and debug.getinfo(2).func ~= require then
     end
     return os.exit(false, true)
   end
-  xpcall(run, err_hand)
+  local ldt = require('ldt')
+  ldt.guard(run)
 end
 return NomsuCompiler

nomsu.moon

@@ -51,7 +51,7 @@ Types = {}
 type_tostring = =>
     "#{@name}(#{concat [repr(x) for x in *@], ", "})"
 Tuple = immutable(nil, {name:"Tuple"})
-for t in *{"File", "Nomsu", "Block", "List", "FunctionCall", "Text", "Dict", "Number", "Word", "Var", "Comment"}
+for t in *{"File", "Nomsu", "Block", "List", "FunctionCall", "Text", "Dict", "Number", "Word", "Var", "Comment", "IndexChain"}
     Types[t] = immutable({"id","value"}, {type:t, name:t, __tostring:type_tostring})
 Types.DictEntry = immutable({"key","value"}, {name:"DictEntry"})
 Types.is_node = (n)->
@@ -125,7 +125,7 @@ node_id = 0
 setmetatable(NOMSU_DEFS, {__index:(key)=>
     make_node = (start, value, stop)->
         node_id = node_id + 1
-        if type(value) == 'table' then error(value)-- = Tuple(value)
+        if type(value) == 'table' then error("Not a tuple: #{repr value}")-- = Tuple(value)
         node = Types[key](node_id, value)
         lpeg.userdata.tree_metadata[node] = {
             :start,:stop,filename:lpeg.userdata.filename,source_code:lpeg.userdata.source_code
@@ -680,6 +680,20 @@ class NomsuCompiler
                 --return expr:"nomsu:parse(#{repr @get_source_code(tree.value)}, #{repr @get_line_number(tree.value)}).value[1]"
                 return expr:repr(tree.value)
 
+            when "IndexChain"
+                items = {}
+                for i, item in ipairs(tree.value)
+                    lua = @tree_to_lua item
+                    unless lua.expr
+                        line = @get_line_number(item)
+                        src = @get_source_code(item)
+                        error "#{line}: Cannot index #{colored.yellow src}, since it's not an expression.", 0
+                    if i == 1
+                        insert items, "(#{lua.expr})"
+                    else
+                        insert items, "[ #{lua.expr}]"
+                return expr:concat(items,"")
+
             when "Block"
                 lua_bits = {}
                 locals = {}
@@ -1145,6 +1159,8 @@ if arg and debug.getinfo(2).func != require
 
     -- Note: xpcall has a slightly different API in Lua <=5.1 vs. >=5.2, but this works
     -- for both APIs
-    xpcall(run, err_hand)
+    ldt = require 'ldt'
+    ldt.guard run
+    --xpcall(run, err_hand)
 
 return NomsuCompiler

nomsu.peg

@@ -18,9 +18,15 @@ indented_block (Block):
 inline_nomsu (Nomsu): "\" inline_expression
 indented_nomsu (Nomsu): "\" expression
 
-inline_expression:
+index_chain (IndexChain):
+    {| noindex_inline_expression ("." ((({} ({|{%operator / (!number plain_word)}|} -> Tuple) {}) -> Text) / noindex_inline_expression))+ |} -> Tuple
+
+noindex_inline_expression:
     number / variable / inline_text / inline_list / inline_dict / inline_nomsu
     / ("(" %ws* (inline_functioncall / inline_expression) %ws* ")")
+
+inline_expression:
+    index_chain / noindex_inline_expression 
 indented_expression:
     indented_text / indented_nomsu / indented_list / indented_dict / indented_block
 expression: