Made iteration easier to work with by using .__inext and .__next for

custom iteration, and a custom ipairs() and pairs() to use that.

builtin_metatables.lua

@@ -186,8 +186,11 @@ co_mt = {
     return math.huge
   end,
   __call = coroutine.resume,
-  __next = function(self, k)
+  __inext = function(self, k)
     local ok, val = coroutine.resume(self)
+    if coroutine.status(self) == 'dead' then
+      return 
+    end
     if ok then
       return (k or 0) + 1, val
     end
@@ -207,6 +210,7 @@ co_mt = {
     return co_mt[k]
   end
 }
+co_mt.__next = co_mt.__inext
 debug.setmetatable(coroutine.create(function() end), co_mt)
 local nil_mt = {
   __type = "Nil",

builtin_metatables.moon

@@ -80,8 +80,9 @@ co_mt =
     as_text: => (tostring(@)\gsub("thread", "Coroutine")).." ("..coroutine.status(@)..")"
     __len: => math.huge
     __call: coroutine.resume
-    __next: (k)=>
+    __inext: (k)=>
         ok, val = coroutine.resume(@)
+        return if coroutine.status(@) == 'dead'
         if ok then return (k or 0) + 1, val
     __index: (k)=>
         if k == (_last_co_i[@] or 0) + 1
@@ -92,6 +93,7 @@ co_mt =
             else
                 return nil
         return co_mt[k]
+co_mt.__next = co_mt.__inext
 debug.setmetatable(coroutine.create(->), co_mt)
 
 nil_mt =

containers.lua

@@ -1,4 +1,4 @@
-local List, Dict, Undict, DictEntries, _undict_mt, _dict_mt, _dict_entries_mt
+local List, Dict, Undict, _undict_mt, _dict_mt
 local insert, remove, concat
 do
   local _obj_0 = table
@@ -426,62 +426,6 @@ Undict = function(d)
   end)())
   return u
 end
-local _dict_entries_mt
-_dict_entries_mt = {
-  __type = "a Dict's Entries",
-  __index = function(self, k)
-    if type(k) == 'number' then
-      if k == 0 then
-        return nil
-      end
-      if k < 0 then
-        if k < 0 then
-          k = #self.dict + k + 1
-        end
-      end
-      local i, last_k = self._last_i, self._last_k
-      if k < i then
-        i, last_k = 0, nil
-      end
-      local d = self.dict
-      for i = i + 1, k do
-        last_k = next(d, last_k)
-        if last_k == nil then
-          return nil
-        end
-      end
-      self._last_i, self._last_k = k, last_k
-      return Dict({
-        key = last_k,
-        d[last_k]
-      })
-    else
-      return _dict_entries_mt[k]
-    end
-  end,
-  __len = function(self)
-    return #self.dict
-  end,
-  __eq = function(self, other)
-    return type(other) == type(self) and getmetatable(other) == getmetatable(self) and other.dict == self.dict
-  end,
-  __tostring = function(self)
-    return "(entries in " .. tostring(self.dict) .. ")"
-  end,
-  as_nomsu = function(self)
-    return "(entries in " .. _dict_mt.as_nomsu(self.dict) .. ")"
-  end,
-  as_lua = function(self)
-    return "entries_in" .. _dict_mt.as_lua(self.dict)
-  end
-}
-DictEntries = function(d)
-  return setmetatable({
-    dict = d,
-    _last_i = 0,
-    _last_k = nil
-  }, _dict_entries_mt)
-end
 _dict_mt = {
   __type = "a Dict",
   __eq = function(self, other)
@@ -540,8 +484,14 @@ _dict_mt = {
       return _accum_0
     end)(), ", ") .. "}"
   end,
-  as_iterable = function(self)
-    return DictEntries(self)
+  __inext = function(self, key)
+    local nextkey, value = next(self, key)
+    if nextkey ~= nil then
+      return nextkey, Dict({
+        key = nextkey,
+        value = value
+      })
+    end
   end,
   __band = function(self, other)
     return Dict((function()
@@ -662,6 +612,5 @@ Dict = function(t, more, ...)
 end
 return {
   List = List,
-  Dict = Dict,
-  DictEntries = DictEntries
+  Dict = Dict
 }

containers.moon

@@ -1,5 +1,5 @@
 -- This file contains container classes, i.e. Lists and Dicts, plus some extended string functionality
-local List, Dict, Undict, DictEntries, _undict_mt, _dict_mt, _dict_entries_mt
+local List, Dict, Undict, _undict_mt, _dict_mt
 {:insert,:remove,:concat} = table
 
 as_nomsu = =>
@@ -199,34 +199,6 @@ Undict = (d)->
     compliments[u] = Dict{k,true for k,v in pairs(d) when v}
     return u
 
-local _dict_entries_mt
-_dict_entries_mt =
-    __type: "a Dict's Entries"
-    __index: (k)=>
-        if type(k) == 'number'
-            return nil if k == 0
-            if k < 0 then k = #@dict+k+1 if k < 0
-            i, last_k = @_last_i, @_last_k
-            if k < i
-                i, last_k = 0, nil
-            d = @dict
-            for i=i+1,k
-                last_k = next(d, last_k)
-                return nil if last_k == nil
-            @_last_i, @_last_k = k, last_k
-            return Dict{key:last_k, d[last_k]}
-        else
-            return _dict_entries_mt[k]
-    __len: => #@dict
-    __eq: (other)=>
-        type(other) == type(@) and getmetatable(other) == getmetatable(@) and other.dict == @dict
-    __tostring: => "(entries in "..tostring(@dict)..")"
-    as_nomsu: => "(entries in ".._dict_mt.as_nomsu(@dict)..")"
-    as_lua: => "entries_in".._dict_mt.as_lua(@dict)
-
-DictEntries = (d)->
-    setmetatable {dict:d, _last_i:0, _last_k:nil}, _dict_entries_mt
-
 _dict_mt =
     __type: "a Dict"
     __eq: (other)=>
@@ -247,7 +219,10 @@ _dict_mt =
         "{"..concat([v == true and "."..as_nomsu(k) or ".#{as_nomsu(k)} = #{as_nomsu(v)}" for k,v in pairs @], ", ").."}"
     as_lua: =>
         "a_Dict{"..concat(["[ #{as_lua(k)}]= #{as_lua(v)}" for k,v in pairs @], ", ").."}"
-    as_iterable: => DictEntries(@)
+    __inext: (key)=>
+        nextkey, value = next(@, key)
+        if nextkey != nil
+            return nextkey, Dict{key:nextkey, value:value}
     __band: (other)=>
         Dict{k,v for k,v in pairs(@) when other[k]}
     __bor: (other)=>
@@ -300,4 +275,4 @@ Dict = (t,more,...)->
             d[k] = v
     return d
 
-return {:List, :Dict, :DictEntries}
+return {:List, :Dict}

lib/core/collections.nom

@@ -180,7 +180,6 @@ test:
     for $ in $r:
         $visited, add $
     assume ($visited == [1, 3, 5, 7, 9])
-$(inext) = (=lua "ipairs({})")
 $range_mt = {
     .__type = "a Range"
     .__index =
@@ -212,7 +211,8 @@ $range_mt = {
                     ($self.last == $other.last) and ($self.step == $other.step)
     
     .backwards = (for $self ($self.last to $self.first by (- $self.step)))
-    .__ipairs = (for $self: return $(inext) $self 0)
+    .__inext = $(inext)
+    .__next = $(inext)
     .as_text =
         for $self:
             if ($self.step == 1):

lib/core/control_flow.nom

@@ -167,13 +167,9 @@ test:
     # This uses Lua's approach of only allowing loop-scoped variables in a loop
     if (($var.type == "Action") and ($var.stub == "1 =")):
         [$key, $value] = [$var.1, $var.3]
-        go to (vars set)
-    if (($var.type == "Action") and ($var.stub == "1 at")):
-        [$key, $value] = [$var.3, $var.1]
     ..else:
         [$key, $value] = [nil, $var]
 
-    --- (vars set) ---
     unless $value:
         at (this tree) fail "No value here"
 
@@ -211,21 +207,16 @@ test:
     if $key:
         $loop =
             Lua ("
-                local _iterating = \($iterable as lua expr);
-                local _next = getmetatable(_iterating).__next or next;
-                for \($key as lua identifier),\($value as lua identifier) in _next,_iterating,nil do
-                    if \($value as lua identifier) == nil and _1_is_a_dead_coroutine(_iterating) then break end
+                for \($key as lua identifier),\($value as lua identifier) in pairs(\($iterable as lua expr)) do
             ")
     ..else:
         $loop =
             Lua ("
-                local _iterating = _1_as_an_iterable(\($iterable as lua expr))
-                for _i=1,#_iterating do
-                    local \($value as lua identifier) = _iterating[_i]
-                    if \($value as lua identifier) == nil and _1_is_a_dead_coroutine(_iterating) then break end
+                for _i,\($value as lua identifier) in _ipairs(\($iterable as lua expr)) do
             ")
 
     --- (loop set) ---
+    # TODO: don't always wrap in block
     $lua =
         Lua ("
             do -- for-loop

nomsu_environment.lua

@@ -3,10 +3,10 @@ do
   local _obj_0 = require("code_obj")
   NomsuCode, LuaCode, Source = _obj_0.NomsuCode, _obj_0.LuaCode, _obj_0.Source
 end
-local List, Dict, DictEntries
+local List, Dict
 do
   local _obj_0 = require('containers')
-  List, Dict, DictEntries = _obj_0.List, _obj_0.Dict, _obj_0.DictEntries
+  List, Dict = _obj_0.List, _obj_0.Dict
 end
 local Text = require('text')
 local SyntaxTree = require("syntax_tree")
@@ -73,21 +73,39 @@ _1_as_text = function(x)
   end
   return tostring(x)
 end
-local _1_as_an_iterable
-_1_as_an_iterable = function(x)
-  do
-    local mt = getmetatable(x)
-    if mt then
-      if mt.as_iterable then
-        return mt.as_iterable(x)
-      end
+local nomsu_pairs
+nomsu_pairs = function(self)
+  local mt = getmetatable(self)
+  if mt and mt.__next then
+    return mt.__next, self, nil
+  else
+    return next, self, nil
+  end
+end
+local inext
+if _VERSION == "Lua 5.2" or _VERSION == "Lua 5.1" then
+  inext = function(self, i)
+    local value = self[i + 1]
+    if value ~= nil then
+      return i + 1, value
     end
   end
-  return x
+else
+  inext = ipairs({ })
+end
+local nomsu_ipairs
+nomsu_ipairs = function(self)
+  local mt = getmetatable(self)
+  if mt and mt.__inext then
+    return mt.__inext, self, 0
+  else
+    return inext, self, 0
+  end
 end
 local nomsu_environment
 nomsu_environment = Importer({
   next = next,
+  inext = inext,
   unpack = unpack or table.unpack,
   setmetatable = setmetatable,
   rawequal = rawequal,
@@ -122,8 +140,9 @@ nomsu_environment = Importer({
   math = math,
   io = io,
   load = load,
-  pairs = pairs,
+  pairs = nomsu_pairs,
   ipairs = ipairs,
+  _ipairs = nomsu_ipairs,
   jit = jit,
   _VERSION = _VERSION,
   LUA_VERSION = (jit and jit.version or _VERSION),
@@ -132,7 +151,6 @@ nomsu_environment = Importer({
   a_List = List,
   a_Dict = Dict,
   Text = Text,
-  Dict_Entries = DictEntries,
   lpeg = lpeg,
   re = re,
   Files = Files,

nomsu_environment.moon

@@ -1,7 +1,7 @@
 -- This file defines the environment in which Nomsu code runs, including some
 -- basic bootstrapping functionality.
 {:NomsuCode, :LuaCode, :Source} = require "code_obj"
-{:List, :Dict, :DictEntries} = require 'containers'
+{:List, :Dict} = require 'containers'
 Text = require 'text'
 SyntaxTree = require "syntax_tree"
 Files = require "files"
@@ -44,25 +44,38 @@ _1_as_text = (x)->
     if x == false then return "no"
     return tostring(x)
 
-_1_as_an_iterable = (x)->
-    if mt = getmetatable(x)
-        if mt.as_iterable
-            return mt.as_iterable(x)
-    return x
+nomsu_pairs = =>
+    mt = getmetatable(@)
+    if mt and mt.__next
+        return mt.__next, @, nil
+    else
+        return next, @, nil
+inext = if _VERSION == "Lua 5.2" or _VERSION == "Lua 5.1"
+    inext = (i)=>
+        value = @[i+1]
+        return i+1, value if value != nil
+else ipairs{}
+nomsu_ipairs = =>
+    mt = getmetatable(@)
+    if mt and mt.__inext
+        return mt.__inext, @, 0
+    else
+        return inext, @, 0
 
 local nomsu_environment
 nomsu_environment = Importer{
     -- Lua stuff:
-    :next, unpack: unpack or table.unpack, :setmetatable, :rawequal, :getmetatable, :pcall,
+    :next, :inext, unpack: unpack or table.unpack, :setmetatable, :rawequal, :getmetatable, :pcall,
     yield:coroutine.yield, resume:coroutine.resume, coroutine_status_of:coroutine.status,
     coroutine_wrap:coroutine.wrap, coroutine_from: coroutine.create,
     :error, :package, :os, :require, :tonumber, :tostring, :string, :xpcall,
     :print, :loadfile, :rawset, :_VERSION, :collectgarbage, :rawget, :rawlen,
     :table, :assert, :dofile, :loadstring, lua_type_of:type, :select, :math, :io, :load,
-    :pairs, :ipairs, :jit, :_VERSION, LUA_VERSION: (jit and jit.version or _VERSION),
+    pairs:nomsu_pairs, :ipairs, _ipairs:nomsu_ipairs, :jit,
+    :_VERSION, LUA_VERSION: (jit and jit.version or _VERSION),
     LUA_API: _VERSION, Bit: (jit or _VERSION == "Lua 5.2") and require('bitops') or nil
     -- Nomsu types:
-    a_List:List, a_Dict:Dict, Text:Text, Dict_Entries:DictEntries,
+    a_List:List, a_Dict:Dict, Text:Text,
     -- Utilities and misc.
     lpeg:lpeg, re:re, Files:Files,
     :SyntaxTree, TESTS: Dict({}), globals: Dict({}),