diff --git a/.gitignore b/.gitignore
index 00aab34cd..9852a9075 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
 t.*
 coverage
 node_modules
+*.swp
+*.vim
+src/*.js
diff --git a/lib/lexer.js b/lib/lexer.js
index 602e868cd..f7a3ae8c6 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -117,7 +117,7 @@ exports.checkConsistency = function(camel, id){
   }
 };
 exports.doID = function(code, index){
-  var regexMatch, input, id, e, last, ref$, tag, ref1$, that;
+  var regexMatch, input, id, e, last, ref$, tag, ref1$, that, a;
   input = (regexMatch = (ID.lastIndex = index, ID).exec(code))[0];
   if (!input) {
     return 0;
@@ -339,10 +339,13 @@ exports.doID = function(code, index){
       break;
     case 'to':
     case 'til':
-      this.forange() && this.tokens.push(['FROM', '', this.line, this.column], ['STRNUM', '0', this.line, this.column]);
-      if (this.fget('from')) {
-        this.fset('from', false);
-        this.fset('by', true);
+      if (this.forange()) {
+        this.tokens.push(['FROM', '', this.line, this.column]);
+        this.tokens.push(['STRNUM', '0', this.line, this.column]);
+      }
+      if ((a = this.flags[this.closes.length]) && a.from) {
+        a.from = false;
+        a.by = true;
         tag = 'TO';
       } else if (!last.callable && last[0] === 'STRNUM' && (ref$ = this.tokens)[ref$.length - 2][0] === '[') {
         last[0] = 'RANGE';
@@ -1678,8 +1681,10 @@ function addImplicitBraces(tokens){
   }
 }
 function expandLiterals(tokens){
-  var i, fromNum, token, sig, ref$, ref1$, lno, cno, ref2$, ref3$, ref4$, char, toNum, tochar, byNum, byp, ref5$, ts, enc, add, i$, n, ref6$, ref7$, len$, word, that;
+  var i, nFrom, nTo, token, sig, ref$, ref1$, lno, cno, ref2$, char, tochar, nBy, byp, ref3$, ts, enc, i$, nI, ref4$, ref5$, len$, word, that;
   i = 0;
+  nFrom = null;
+  nTo = null;
   while (token = tokens[++i]) {
     switch (token[0]) {
     case 'STRNUM':
@@ -1700,57 +1705,66 @@ function expandLiterals(tokens){
         tokens[i + 2][0] = 'RANGE_BY';
       }
       token.op = token[1];
-      fromNum = 0;
+      nFrom = 0;
       // fallthrough
     case 'RANGE':
       lno = token[2];
       cno = token[3];
-      if (fromNum != null || (tokens[i - 1][0] === '[' && tokens[i + 1][0] === 'STRNUM' && ((tokens[i + 2][0] === ']' && (((ref2$ = tokens[i + 1][1].charAt(0)) === '\'' || ref2$ === '"') || +tokens[i + 1][1] >= 0)) || (tokens[i + 2][0] === 'RANGE_BY' && ((ref2$ = tokens[i + 3]) != null ? ref2$[0] : void 8) === 'STRNUM' && ((ref3$ = tokens[i + 4]) != null ? ref3$[0] : void 8) === ']')))) {
-        if (fromNum == null) {
-          ref4$ = decode(token[1], lno), fromNum = ref4$[0], char = ref4$[1];
+      if (tokens[i - 2][0] !== 'DOT' && (nFrom !== null || (tokens[i - 1][0] === '[' && tokens[i + 1][0] === 'STRNUM' && ((tokens[i + 2][0] === ']' && (tokens[i + 1][1][0] === '"' || tokens[i + 1][1][0] === "'" || +tokens[i + 1][1] >= 0)) || (tokens[i + 2][0] === 'RANGE_BY' && tokens[i + 3] && tokens[i + 4] && tokens[i + 3][0] === 'STRNUM' && tokens[i + 4][0] === ']'))))) {
+        if (nFrom === null) {
+          ref2$ = decode(token[1], lno), nFrom = ref2$[0], char = ref2$[1];
         }
-        ref4$ = decode(tokens[i + 1][1], lno), toNum = ref4$[0], tochar = ref4$[1];
-        if (toNum == null || char ^ tochar) {
+        ref2$ = decode(tokens[i + 1][1], lno), nTo = ref2$[0], tochar = ref2$[1];
+        if (nTo == null || char ^ tochar) {
           carp('bad "to" in range', lno);
         }
-        byNum = 1;
-        if (byp = ((ref4$ = tokens[i + 2]) != null ? ref4$[0] : void 8) === 'RANGE_BY') {
-          if (!(byNum = +((ref5$ = tokens[i + 3]) != null ? ref5$[1] : void 8))) {
+        nBy = 1;
+        if (byp = ((ref2$ = tokens[i + 2]) != null ? ref2$[0] : void 8) === 'RANGE_BY') {
+          if (!(nBy = +((ref3$ = tokens[i + 3]) != null ? ref3$[1] : void 8))) {
             carp('bad "by" in range', tokens[i + 2][2]);
           }
-        } else if (fromNum > toNum) {
-          byNum = -1;
+        } else if (nFrom > nTo) {
+          nBy = -1;
         }
         ts = [];
         enc = char ? character : String;
-        add = fn$;
         if (token.op === 'to') {
-          for (i$ = fromNum; byNum < 0 ? i$ >= toNum : i$ <= toNum; i$ += byNum) {
-            n = i$;
-            add();
+          for (i$ = nFrom; nBy < 0 ? i$ >= nTo : i$ <= nTo; i$ += nBy) {
+            nI = i$;
+            ts.push(['STRNUM', enc(nI), lno, cno]);
+            ts.push([',', ',', lno, cno]);
+            if (ts.length > 0x10000) {
+              carp('range limit exceeded', lno);
+            }
           }
         } else {
-          for (i$ = fromNum; byNum < 0 ? i$ > toNum : i$ < toNum; i$ += byNum) {
-            n = i$;
-            add();
+          for (i$ = nFrom; nBy < 0 ? i$ > nTo : i$ < nTo; i$ += nBy) {
+            nI = i$;
+            ts.push(['STRNUM', enc(nI), lno, cno]);
+            ts.push([',', ',', lno, cno]);
+            if (ts.length > 0x10000) {
+              carp('range limit exceeded', lno);
+            }
           }
         }
-        ts.pop() || carp('empty range', lno);
+        if (!ts.pop()) {
+          carp('empty range', lno);
+        }
         tokens.splice.apply(tokens, [i, 2 + 2 * byp].concat(arrayFrom$(ts)));
         i += ts.length - 1;
       } else {
         token[0] = 'STRNUM';
-        if (((ref6$ = tokens[i + 2]) != null ? ref6$[0] : void 8) === 'RANGE_BY') {
+        if (((ref4$ = tokens[i + 2]) != null ? ref4$[0] : void 8) === 'RANGE_BY') {
           tokens.splice(i + 2, 1, ['BY', 'by', lno, cno]);
         }
         tokens.splice(i + 1, 0, ['TO', token.op, lno, cno]);
       }
-      fromNum = null;
+      nFrom = null;
       break;
     case 'WORDS':
       ts = [['[', '[', lno = token[2], cno = token[3]]];
-      for (i$ = 0, len$ = (ref7$ = token[1].match(/\S+/g) || '').length; i$ < len$; ++i$) {
-        word = ref7$[i$];
+      for (i$ = 0, len$ = (ref5$ = token[1].match(/\S+/g) || '').length; i$ < len$; ++i$) {
+        word = ref5$[i$];
         ts.push(['STRNUM', string('\'', word, lno), lno, cno], [',', ',', lno, cno]);
       }
       tokens.splice.apply(tokens, [i, 1].concat(arrayFrom$(ts), [[']', ']', lno, cno]]));
@@ -1760,7 +1774,7 @@ function expandLiterals(tokens){
       if (that = tokens[i - 1]) {
         if (that[1] === 'new') {
           tokens.splice(i++, 0, ['PARAM(', '', token[2], token[3]], [')PARAM', '', token[2], token[3]], ['->', '', token[2], token[3]]);
-        } else if ((ref7$ = that[0]) === 'FUNCTION' || ref7$ === 'GENERATOR' || ref7$ === 'LET') {
+        } else if ((ref5$ = that[0]) === 'FUNCTION' || ref5$ === 'GENERATOR' || ref5$ === 'LET') {
           tokens.splice(i, 0, ['CALL(', '', token[2], token[3]], [')CALL', '', token[2], token[3]]);
           i += 2;
         }
@@ -1786,7 +1800,7 @@ function expandLiterals(tokens){
       }
       break;
     case 'BIOP':
-      if (!token.spaced && ((ref7$ = token[1]) === '+' || ref7$ === '-') && tokens[i + 1][0] !== ')') {
+      if (!token.spaced && ((ref5$ = token[1]) === '+' || ref5$ === '-') && tokens[i + 1][0] !== ')') {
         tokens[i][0] = '+-';
       }
       continue;
@@ -1797,11 +1811,6 @@ function expandLiterals(tokens){
       tokens.splice(++i, 0, [',', ',', token[2], token[3]]);
     }
   }
-  function fn$(){
-    if (0x10000 < ts.push(['STRNUM', enc(n), lno, cno], [',', ',', lno, cno])) {
-      carp('range limit exceeded', lno);
-    }
-  }
 }
 function detectEnd(tokens, i, ok, go){
   var levels, token, tag;
diff --git a/src/ast.ls b/src/ast.ls
index ae8bcd41d..38b4d698b 100644
--- a/src/ast.ls
+++ b/src/ast.ls
@@ -3145,8 +3145,11 @@ UTILS =
 
     # Copies properties from right to left.
     import: '''function(obj, src){
-      var own = {}.hasOwnProperty;
-      for (var key in src) if (own.call(src, key)) obj[key] = src[key];
+      for (var key in src) {
+        if (Object.hasOwnProperty.call(src, key)) {
+          obj[key] = src[key];
+        }
+      }
       return obj;
     }'''
     import-all: '''function(obj, src){
diff --git a/src/lexer.ls b/src/lexer.ls
index 87fe3deb9..c785322dd 100644
--- a/src/lexer.ls
+++ b/src/lexer.ls
@@ -250,14 +250,21 @@ exports <<<
                     return 4
                 @forange! and tag = 'FROM'
             case 'to' 'til'
-                @forange! and @tokens.push do
-                    ['FROM' '' @line, @column] ['STRNUM' '0' @line, @column]
-                if @fget 'from'
-                    @fset 'from' false
-                    @fset 'by' true
-                    tag = 'TO'
-                else if not last.callable and last.0 is 'STRNUM' and @tokens[*-2].0 is '['
-                    last <<< 0:'RANGE' op: id
+                # check <for> without <from>
+                if @forange!
+                    @tokens.push ['FROM' '' @line, @column]
+                    @tokens.push ['STRNUM' '0' @line, @column]
+                # check <from> flag
+                if (a = @flags[@closes.length]) and a.from
+                    # <from> is done, current is <to>, next is <by>
+                    a.from = false
+                    a.by   = true
+                    tag    = 'TO'
+                # check at the array start
+                else if not last.callable and last.0 == 'STRNUM' and @tokens[*-2].0 == '['
+                    # STRNUM is converted to RANGE
+                    last.0  = 'RANGE'
+                    last.op = id
                     return id.length
                 else if ']' in @closes
                     @token 'TO' id
@@ -1218,7 +1225,8 @@ character = if not JSON? then uxxxx else ->
 # - Insert `, ` after each non-callable token facing an argument token.
 !function expand-literals tokens
     i = 0
-    var from-num
+    nFrom = null
+    nTo   = null
     while token = tokens[++i]
         switch token.0
         case 'STRNUM'
@@ -1239,46 +1247,89 @@ character = if not JSON? then uxxxx else ->
             if tokens[i + 2].0 is 'BY'
                 tokens[i + 2].0 = 'RANGE_BY'
             token.op = token.1
-            from-num = 0
+            nFrom = 0
             fallthrough
         case 'RANGE'
+            # {{{
+            # prepare
             lno = token.2
             cno = token.3
-            if from-num? or (tokens[i-1].0 is '['
-            and tokens[i + 1].0 is 'STRNUM'
-            and ((tokens[i + 2].0 is ']'
-                and (tokens[i + 1].1.char-at(0) in ['\'' '"']
-                    or +tokens[i + 1].1 >= 0))
-                or (tokens[i + 2].0 is 'RANGE_BY'
-                and tokens[i + 3]?.0 is 'STRNUM'
-                and tokens[i + 4]?.0 is ']')))
-                unless from-num?
-                    [from-num, char] = decode token.1, lno
-                [to-num, tochar] = decode tokens[i + 1].1, lno
-                carp 'bad "to" in range' lno if not to-num? or char .^. tochar
-                by-num = 1
-                if byp = tokens[i + 2]?.0 is 'RANGE_BY'
-                    carp 'bad "by" in range' tokens[i + 2].2 unless by-num = +tokens[i + 3]?.1
-                else if from-num > to-num
-                    by-num = -1
-                ts = []
-                enc = if char then character else String
-                add = !->
-                     if 0x10000 < ts.push ['STRNUM' enc n; lno, cno] [',' ',' lno, cno]
-                         carp 'range limit exceeded' lno
-                if token.op is 'to'
-                    for n from from-num to to-num by by-num then add!
-                else
-                    for n from from-num til to-num by by-num then add!
-                ts.pop! or carp 'empty range' lno
-                tokens.splice i, 2 + 2 * byp, ...ts
-                i += ts.length - 1
+            # check token sequence,
+            # range with accessor should not be expanded
+            if tokens[i - 2].0 != 'DOT' and
+               # implicit range (when <from> flag-number is set) or,
+               (nFrom != null or
+               # there is a "simple" numeric range startup with..
+               (tokens[i - 1].0 == '[' and
+                tokens[i + 1].0 == 'STRNUM' and
+                # either end of the range..
+                ((tokens[i + 2].0 == ']' and
+                  # with a string literal(?) or a positive number..
+                  # Q: why this exact check order should matter?
+                  (tokens[i + 1].1.0 == '"' or
+                   tokens[i + 1].1.0 == "'" or
+                   +tokens[i + 1].1 >= 0)) or
+                 # ..or, a full <range_by>
+                 (tokens[i + 2].0 == 'RANGE_BY' and
+                  tokens[i + 3] and tokens[i + 4] and
+                  tokens[i + 3].0 == 'STRNUM' and
+                  tokens[i + 4].0 == ']'))))
+                    # do RANGE expansion
+                    # determine <from> number
+                    if nFrom == null
+                        # Q: the purpose of char?
+                        [nFrom, char] = decode token.1, lno
+                    # determine <to> number
+                    [nTo, tochar] = decode tokens[i + 1].1, lno
+                    carp 'bad "to" in range' lno if not nTo? or char .^. tochar
+                    # determine <by> number
+                    nBy = 1
+                    if byp = tokens[i + 2]?.0 is 'RANGE_BY'
+                        carp 'bad "by" in range' tokens[i + 2].2 unless nBy = +tokens[i + 3]?.1
+                    else if nFrom > nTo
+                        nBy = -1
+                    # prepare tokens stack
+                    ts = []
+                    # prepare encoder function
+                    enc = if char
+                        then character
+                        else String
+                    # fill the stack
+                    if token.op == 'to'
+                        for nI from nFrom to nTo by nBy
+                            ts.push ['STRNUM', (enc nI), lno, cno]
+                            ts.push [',', ',', lno, cno]
+                            if ts.length > 0x10000
+                                carp 'range limit exceeded' lno
+                    else
+                        for nI from nFrom til nTo by nBy
+                            ts.push ['STRNUM', (enc nI), lno, cno]
+                            ts.push [',', ',', lno, cno]
+                            if ts.length > 0x10000
+                                carp 'range limit exceeded' lno
+                    # remove last (garbage) token from the stack
+                    # and make a short check
+                    if not ts.pop!
+                        carp 'empty range' lno
+                    # replace this <RANGE> with stacked tokens
+                    # the tokens array should be modified *in place*
+                    #tokens = (tokens.slice 0, i) ++ ts ++ (tokens.slice i + 2 + 2*byp)
+                    tokens.splice i, 2 + 2 * byp, ...ts
+                    # advance index
+                    i += ts.length - 1
+                    # done
             else
-                token.0 = 'STRNUM'
-                if tokens[i + 2]?.0 is 'RANGE_BY'
-                    tokens.splice i + 2, 1, ['BY' 'by' lno, cno]
-                tokens.splice i + 1, 0, ['TO', token.op, lno, cno]
-            from-num = null
+                    token.0 = 'STRNUM'
+                    if nFrom != null
+                        # set implicit <from> number
+                        token.1 = '0'
+                    else if tokens[i + 2]?.0 is 'RANGE_BY'
+                        tokens.splice i + 2, 1, ['BY' 'by' lno, cno]
+                    # insert <TO>
+                    tokens.splice i + 1, 0, ['TO', token.op, lno, cno]
+            # clear <from> flag-number
+            nFrom = null
+            # }}}
         case 'WORDS'
             ts = [['[' '[' lno = token.2, cno = token.3]]
             for word in token.1.match /\S+/g or ''
@@ -1302,7 +1353,8 @@ character = if not JSON? then uxxxx else ->
             if not token.spaced and token.1 in <[ + - ]> and tokens[i + 1].0 isnt ')'
                 tokens[i].0 = '+-'
             continue
-        default continue
+        default
+            continue
         if token.spaced and tokens[i + 1].0 in ARG
             tokens.splice ++i, 0 [',' ',' token.2, token.3]