add numeric for loop comprehensions/decorator, fixes #45

Author: leafo

docs/reference.md

@@ -415,6 +415,12 @@ Using multiple `for` clauses is the same as using nested loops:
     points = [{x,y} for x in *x_coords for y in *y_coords]
     ```
 
+Numeric for loops can also be used in comprehensions:
+
+    ```moon
+    evens = [i for i=1,100 when i % 2 == 0]
+    ```
+
 ### Table Comprehensions
 
 The syntax for table comprehensions is very similar, only differing by using `{` and

moonscript/parse.lua

@@ -447,9 +447,10 @@ local build_grammar = wrap_env(function()
 
 		TblComprehension = sym"{" * Ct(Exp * (sym"," * Exp)^-1) * CompInner * sym"}" / mark"tblcomprehension",
 
-		CompInner = Ct(CompFor * CompClause^0),
-		CompFor = key"for" * Ct(NameList) * key"in" * (sym"*" * Exp / mark"unpack" + Exp) / mark"for",
-		CompClause = CompFor + key"when" * Exp / mark"when",
+		CompInner = Ct((CompForEach + CompFor) * CompClause^0),
+		CompForEach = key"for" * Ct(NameList) * key"in" * (sym"*" * Exp / mark"unpack" + Exp) / mark"foreach",
+		CompFor = key "for" * Name * sym"=" * Ct(Exp * sym"," * Exp * (sym"," * Exp)^-1) / mark"for",
+		CompClause = CompFor + CompForEach + key"when" * Exp / mark"when",
 
 		Assign = sym"=" * (Ct(With + If + Switch) + Ct(TableBlock + ExpListLow)) / mark"assign",
 		Update = ((sym"..=" + sym"+=" + sym"-=" + sym"*=" + sym"/=" + sym"%=" + sym"or=" + sym"and=") / trim) * Exp / mark"update",

moonscript/transform.lua

@@ -66,12 +66,16 @@ apply_to_last = function(stms, fn)
     local _accum_0 = { }
     local _len_0 = 1
     for i, stm in ipairs(stms) do
+      local _value_0
       if i == last_exp_id then
-        _accum_0[_len_0] = fn(stm)
+        _value_0 = fn(stm)
       else
-        _accum_0[_len_0] = stm
+        _value_0 = stm
+      end
+      if _value_0 ~= nil then
+        _accum_0[_len_0] = _value_0
+        _len_0 = _len_0 + 1
       end
-      _len_0 = _len_0 + 1
     end
     return _accum_0
   end)()
@@ -291,9 +295,25 @@ construct_comprehension = function(inner, clauses)
   local current_stms = inner
   for _, clause in reversed(clauses) do
     local t = clause[1]
-    if t == "for" then
+    local _exp_0 = t
+    if "for" == _exp_0 then
+      local name, bounds
+      do
+        local _obj_0 = clause
+        _, name, bounds = _obj_0[1], _obj_0[2], _obj_0[3]
+      end
+      current_stms = {
+        "for",
+        name,
+        bounds,
+        current_stms
+      }
+    elseif "foreach" == _exp_0 then
       local names, iter
-      _, names, iter = unpack(clause)
+      do
+        local _obj_0 = clause
+        _, names, iter = _obj_0[1], _obj_0[2], _obj_0[3]
+      end
       current_stms = {
         "foreach",
         names,
@@ -302,9 +322,12 @@ construct_comprehension = function(inner, clauses)
         },
         current_stms
       }
-    elseif t == "when" then
+    elseif "when" == _exp_0 then
       local cond
-      _, cond = unpack(clause)
+      do
+        local _obj_0 = clause
+        _, cond = _obj_0[1], _obj_0[2]
+      end
       current_stms = {
         "if",
         cond,
@@ -440,15 +463,19 @@ local Statement = Transformer({
       local _list_0 = names
       for _index_0 = 1, #_list_0 do
         local name = _list_0[_index_0]
+        local _value_0
         if type(name) == "table" then
-          _accum_0[_len_0] = name
+          _value_0 = name
         else
-          _accum_0[_len_0] = {
+          _value_0 = {
             "dot",
             name
           }
         end
-        _len_0 = _len_0 + 1
+        if _value_0 ~= nil then
+          _accum_0[_len_0] = _value_0
+          _len_0 = _len_0 + 1
+        end
       end
       return _accum_0
     end)()
@@ -458,8 +485,11 @@ local Statement = Transformer({
       local _list_0 = names
       for _index_0 = 1, #_list_0 do
         local name = _list_0[_index_0]
-        _accum_0[_len_0] = type(name) == "table" and name[2] or name
-        _len_0 = _len_0 + 1
+        local _value_0 = type(name) == "table" and name[2] or name
+        if _value_0 ~= nil then
+          _accum_0[_len_0] = _value_0
+          _len_0 = _len_0 + 1
+        end
       end
       return _accum_0
     end)()
@@ -681,17 +711,21 @@ local Statement = Transformer({
       local _accum_0 = { }
       local _len_0 = 1
       for i, name in ipairs(node.names) do
+        local _value_0
         if ntype(name) == "table" then
           do
             local _with_0 = NameProxy("des")
             local proxy = _with_0
             insert(destructures, destructure.build_assign(name, proxy))
-            _accum_0[_len_0] = _with_0
+            _value_0 = _with_0
           end
         else
-          _accum_0[_len_0] = name
+          _value_0 = name
+        end
+        if _value_0 ~= nil then
+          _accum_0[_len_0] = _value_0
+          _len_0 = _len_0 + 1
         end
-        _len_0 = _len_0 + 1
       end
       return _accum_0
     end)()
@@ -872,8 +906,10 @@ local Statement = Transformer({
           else
             _value_0 = tuple
           end
-          _accum_0[_len_0] = _value_0
-          _len_0 = _len_0 + 1
+          if _value_0 ~= nil then
+            _accum_0[_len_0] = _value_0
+            _len_0 = _len_0 + 1
+          end
           _continue_0 = true
         until true
         if not _continue_0 then

moonscript/transform.moon

@@ -140,14 +140,19 @@ construct_comprehension = (inner, clauses) ->
   current_stms = inner
   for _, clause in reversed clauses
     t = clause[1]
-    current_stms = if t == "for"
-      _, names, iter = unpack clause
-      {"foreach", names, {iter}, current_stms}
-    elseif t == "when"
-      _, cond = unpack clause
-      {"if", cond, current_stms}
-    else
-      error "Unknown comprehension clause: "..t
+    current_stms = switch t
+      when "for"
+        {_, name, bounds} = clause
+        {"for", name, bounds, current_stms}
+      when "foreach"
+        {_, names, iter} = clause
+        {"foreach", names, {iter}, current_stms}
+      when "when"
+        {_, cond} = clause
+        {"if", cond, current_stms}
+      else
+        error "Unknown comprehension clause: "..t
+
     current_stms = {current_stms}
 
   current_stms[1]

tests/inputs/comprehension.moon

@@ -17,3 +17,17 @@ copy  = {k,v for k,v in pairs x when k != "okay"}
 { xxxx for x in yes }
 { unpack [a*i for i, a in ipairs x] for x in *{{1,2}, {3,4}} }
 
+
+--
+
+n1 = [i for i=1,10]
+n2 = [i for i=1,10 when i % 2 == 1]
+
+aa = [{x,y} for x=1,10 for y=5,14]
+bb = [y for thing in y for i=1,10]
+cc = [y for i=1,10 for thing in y]
+dd = [y for i=1,10 when cool for thing in y when x > 3 when c + 3]
+
+{"hello", "world" for i=1,10}
+
+nil

tests/inputs/syntax.moon

@@ -104,6 +104,7 @@ x = -[x for x in x]
 print "hello" if cool
 print "hello" unless cool
 print "hello" unless 1212 and 3434 -- hello
+print "hello" for i=1,10
 
 print "nutjob"
 

tests/outputs/comprehension.lua

@@ -52,7 +52,7 @@ _ = (function()
   end
   return _tbl_0
 end)()
-return (function()
+_ = (function()
   local _tbl_0 = { }
   local _list_0 = {
     {
@@ -78,4 +78,85 @@ return (function()
     _tbl_0[_key_0] = _val_0
   end
   return _tbl_0
-end)()
+end)()
+local n1 = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for i = 1, 10 do
+    _accum_0[_len_0] = i
+    _len_0 = _len_0 + 1
+  end
+  return _accum_0
+end)()
+local n2 = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for i = 1, 10 do
+    if i % 2 == 1 then
+      _accum_0[_len_0] = i
+      _len_0 = _len_0 + 1
+    end
+  end
+  return _accum_0
+end)()
+local aa = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for x = 1, 10 do
+    for y = 5, 14 do
+      _accum_0[_len_0] = {
+        x,
+        y
+      }
+      _len_0 = _len_0 + 1
+    end
+  end
+  return _accum_0
+end)()
+local bb = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for thing in y do
+    for i = 1, 10 do
+      _accum_0[_len_0] = y
+      _len_0 = _len_0 + 1
+    end
+  end
+  return _accum_0
+end)()
+local cc = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for i = 1, 10 do
+    for thing in y do
+      _accum_0[_len_0] = y
+      _len_0 = _len_0 + 1
+    end
+  end
+  return _accum_0
+end)()
+local dd = (function()
+  local _accum_0 = { }
+  local _len_0 = 1
+  for i = 1, 10 do
+    if cool then
+      for thing in y do
+        if x > 3 then
+          if c + 3 then
+            _accum_0[_len_0] = y
+            _len_0 = _len_0 + 1
+          end
+        end
+      end
+    end
+  end
+  return _accum_0
+end)()
+_ = (function()
+  local _tbl_0 = { }
+  for i = 1, 10 do
+    _tbl_0["hello"] = "world"
+  end
+  return _tbl_0
+end)()
+return nil

tests/outputs/syntax.lua

@@ -107,6 +107,9 @@ end
 if not (1212 and 3434) then
   print("hello")
 end
+for i = 1, 10 do
+  print("hello")
+end
 print("nutjob")
 if hello then
   _ = 343