From 908243ba21503d3b421e0c137dc6bfc8d15bb105 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Tue, 18 Dec 2018 17:34:09 -0800
Subject: [PATCH] Added comprehension form to containers, e.g.
 List(function(add) add(5) end)

---
 containers.lua  | 36 ++++++++++++++++++++++++++++++++++--
 containers.moon | 23 +++++++++++++++++++++--
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/containers.lua b/containers.lua
index ceb92fd..d4514af 100644
--- a/containers.lua
+++ b/containers.lua
@@ -235,7 +235,21 @@ local _list_mt = {
 _list_mt.__index.as_lua = _list_mt.as_lua
 _list_mt.__index.as_nomsu = _list_mt.as_nomsu
 List = function(t)
-  return setmetatable(t, _list_mt)
+  if type(t) == 'table' then
+    return setmetatable(t, _list_mt)
+  elseif type(t) == 'function' then
+    local l = setmetatable({ }, _list_mt)
+    local add
+    add = function(...)
+      for i = 1, select('#', ...) do
+        l[#l + 1] = select(i, ...)
+      end
+    end
+    t(add)
+    return l
+  else
+    return error("Unsupported List type: " .. type(t))
+  end
 end
 local walk_items
 walk_items = function(self, i)
@@ -396,7 +410,25 @@ local _dict_mt = {
   end
 }
 Dict = function(t)
-  return setmetatable(t, _dict_mt)
+  if type(t) == 'table' then
+    return setmetatable(t, _dict_mt)
+  elseif type(t) == 'function' then
+    local d = setmetatable({ }, _dict_mt)
+    local add
+    add = function(...)
+      for i = 1, select('#', ...) do
+        d[select(i, ...)] = true
+      end
+    end
+    local add_1_eq_2
+    add_1_eq_2 = function(k, v)
+      d[k] = v
+    end
+    t(add, add_1_eq_2)
+    return d
+  else
+    return error("Unsupported Dict type: " .. type(t))
+  end
 end
 for i, entry in ipairs(Dict({
   x = 99
diff --git a/containers.moon b/containers.moon
index c713bb6..26c1032 100644
--- a/containers.moon
+++ b/containers.moon
@@ -95,7 +95,16 @@ _list_mt =
 _list_mt.__index.as_lua = _list_mt.as_lua
 _list_mt.__index.as_nomsu = _list_mt.as_nomsu
 
-List = (t)-> setmetatable(t, _list_mt)
+List = (t)->
+    if type(t) == 'table'
+        return setmetatable(t, _list_mt)
+    elseif type(t) == 'function'
+        l = setmetatable({}, _list_mt)
+        add = (...)->
+            for i=1,select('#',...) do l[#l+1] = select(i,...)
+        t(add)
+        return l
+    else error("Unsupported List type: "..type(t))
 
 walk_items = (i)=>
     i = i + 1
@@ -150,7 +159,17 @@ _dict_mt =
             if ret[k] == nil then ret[k] = -v
             else ret[k] -= v
         return Dict(ret)
-Dict = (t)-> setmetatable(t, _dict_mt)
+Dict = (t)->
+    if type(t) == 'table'
+        return setmetatable(t, _dict_mt)
+    elseif type(t) == 'function'
+        d = setmetatable({}, _dict_mt)
+        add = (...)->
+            for i=1,select('#',...) do d[select(i,...)] = true
+        add_1_eq_2 = (k, v)-> d[k] = v
+        t(add, add_1_eq_2)
+        return d
+    else error("Unsupported Dict type: "..type(t))
 
 for i,entry in ipairs(Dict({x:99}))
     assert(i == 1 and entry.key == "x" and entry.value == 99, "ipairs compatibility issue")