Index: compile_rules.py
==================================================================
--- compile_rules.py
+++ compile_rules.py
@@ -1,13 +1,15 @@
 """
 Grammalecte: compile rules
 """
 
 import re
+import os
 import traceback
 import json
 import colorsys
+import time
 
 import compile_rules_js_convert as jsconv
 import compile_rules_graph as crg
 
 
@@ -417,11 +419,11 @@
     dOptPriority = {}
     for sLine in lOptionLines:
         sLine = sLine.strip()
         if sLine.startswith("OPTGROUP/"):
             m = re.match("OPTGROUP/([a-z0-9]+):(.+)$", sLine)
-            lStructOpt.append( (m.group(1), list(map(str.split, m.group(2).split(",")))) )
+            lStructOpt.append( [m.group(1), list(map(str.split, m.group(2).split(",")))] )
         elif sLine.startswith("OPTSOFTWARE:"):
             lOpt = [ [s, {}]  for s in sLine[12:].strip().split() ]  # don’t use tuples (s, {}), because unknown to JS
         elif sLine.startswith("OPT/"):
             m = re.match("OPT/([a-z0-9]+):(.+)$", sLine)
             for i, sOpt in enumerate(m.group(2).split()):
@@ -463,13 +465,22 @@
 def printBookmark (nLevel, sComment, nLine):
     "print bookmark within the rules file"
     print("  {:>6}:  {}".format(nLine, "  " * nLevel + sComment))
 
 
-def make (spLang, sLang, bJavaScript):
+def make (spLang, sLang, bUseCache=False):
     "compile rules, returns a dictionary of values"
     # for clarity purpose, don’t create any file here
+
+    if bUseCache and os.path.isfile("_build/data_cache.json"):
+        print("> don’t rebuild rules, use cache...")
+        sJSON = open("_build/data_cache.json", "r", encoding="utf-8").read()
+        dCacheVars = json.loads(sJSON)
+        print("  build made at: " + time.strftime("%Y-%m-%d %H:%M:%S", time.gmtime(dCacheVars.get("fBuildTime", 0))))
+        return dCacheVars
+
+    fBuildTime = time.time()
 
     print("> read rules file...")
     try:
         lRules = open(spLang + "/rules.grx", 'r', encoding="utf-8").readlines()
     except:
@@ -610,20 +621,25 @@
 
     displayStats(lParagraphRules, lSentenceRules)
 
     print("Unnamed rules: " + str(nRULEWITHOUTNAME))
 
-    dVars = {   "callables": sPyCallables,
-                "callablesJS": sJSCallables,
-                "gctests": sGCTests,
-                "gctestsJS": sGCTestsJS,
-                "paragraph_rules": mergeRulesByOption(lParagraphRules),
-                "sentence_rules": mergeRulesByOption(lSentenceRules),
-                "paragraph_rules_JS": jsconv.writeRulesToJSArray(mergeRulesByOption(lParagraphRulesJS)),
-                "sentence_rules_JS": jsconv.writeRulesToJSArray(mergeRulesByOption(lSentenceRulesJS)) }
+    dVars = {
+        "fBuildTime": fBuildTime,
+        "callables": sPyCallables,
+        "callablesJS": sJSCallables,
+        "gctests": sGCTests,
+        "gctestsJS": sGCTestsJS,
+        "paragraph_rules": mergeRulesByOption(lParagraphRules),
+        "sentence_rules": mergeRulesByOption(lSentenceRules),
+        "paragraph_rules_JS": jsconv.writeRulesToJSArray(mergeRulesByOption(lParagraphRulesJS)),
+        "sentence_rules_JS": jsconv.writeRulesToJSArray(mergeRulesByOption(lSentenceRulesJS))
+    }
     dVars.update(dOptions)
 
     # compile graph rules
-    dVars2 = crg.make(lGraphRule, dDEF, sLang, dOptPriority, bJavaScript)
+    dVars2 = crg.make(lGraphRule, dDEF, sLang, dOptPriority)
     dVars.update(dVars2)
 
+    with open("_build/data_cache.json", "w", encoding="utf-8") as hDst:
+        hDst.write(json.dumps(dVars, ensure_ascii=False))
     return dVars

Index: compile_rules_graph.py
==================================================================
--- compile_rules_graph.py
+++ compile_rules_graph.py
@@ -316,11 +316,11 @@
     else:
         print(" # Unknown action.", sActionId)
         return None
 
 
-def make (lRule, dDef, sLang, dOptPriority, bJavaScript):
+def make (lRule, dDef, sLang, dOptPriority):
     "compile rules, returns a dictionary of values"
     # for clarity purpose, don’t create any file here
 
     # removing comments, zeroing empty lines, creating definitions, storing tests, merging rule lines
     print("  parsing rules...")
@@ -452,10 +452,10 @@
 
     # Result
     return {
         "graph_callables": sPyCallables,
         "graph_callablesJS": sJSCallables,
-        "rules_graphs": dAllGraph,
+        "rules_graphs": str(dAllGraph),
         "rules_graphsJS": str(dAllGraph).replace("True", "true").replace("False", "false"),
-        "rules_actions": dACTIONS,
+        "rules_actions": str(dACTIONS),
         "rules_actionsJS": str(dACTIONS).replace("True", "true").replace("False", "false")
     }

Index: make.py
==================================================================
--- make.py
+++ make.py
@@ -184,11 +184,11 @@
     for sf in os.listdir(spLangPack):
         if not os.path.isdir(spLangPack+"/"+sf):
             hZip.write(spLangPack+"/"+sf, sAddPath+spLangPack+"/"+sf)
 
 
-def create (sLang, xConfig, bInstallOXT, bJavaScript):
+def create (sLang, xConfig, bInstallOXT, bJavaScript, bUseCache):
     "make Grammalecte for project <sLang>"
     oNow = datetime.datetime.now()
     print("============== MAKE GRAMMALECTE [{0}] at {1.hour:>2} h {1.minute:>2} min {1.second:>2} s ==============".format(sLang, oNow))
 
     #### READ CONFIGURATION
@@ -198,11 +198,11 @@
     dVars = xConfig._sections['args']
     dVars['locales'] = dVars["locales"].replace("_", "-")
     dVars['loc'] = str(dict([ [s, [s[0:2], s[3:5], ""]] for s in dVars["locales"].split(" ") ]))
 
     ## COMPILE RULES
-    dResult = compile_rules.make(spLang, dVars['lang'], bJavaScript)
+    dResult = compile_rules.make(spLang, dVars['lang'], bUseCache)
     dVars.update(dResult)
 
     ## READ GRAMMAR CHECKER PLUGINS
     print("PYTHON:")
     print("+ Plugins: ", end="")
@@ -373,10 +373,11 @@
 def main ():
     "build Grammalecte with requested options"
     print("Python: " + sys.version)
     xParser = argparse.ArgumentParser()
     xParser.add_argument("lang", type=str, nargs='+', help="lang project to generate (name of folder in /lang)")
+    xParser.add_argument("-uc", "--use_cache", help="use data cache instead of rebuilding rules", action="store_true")
     xParser.add_argument("-b", "--build_data", help="launch build_data.py (part 1 and 2)", action="store_true")
     xParser.add_argument("-bb", "--build_data_before", help="launch build_data.py (only part 1: before dictionary building)", action="store_true")
     xParser.add_argument("-ba", "--build_data_after", help="launch build_data.py (only part 2: before dictionary building)", action="store_true")
     xParser.add_argument("-d", "--dict", help="generate FSA dictionary", action="store_true")
     xParser.add_argument("-t", "--tests", help="run unit tests", action="store_true")
@@ -440,11 +441,11 @@
 
             # copy dictionaries from Graphspell
             copyGraphspellDictionaries(dVars, xArgs.javascript, xArgs.add_extended_dictionary, xArgs.add_community_dictionary, xArgs.add_personal_dictionary)
 
             # make
-            sVersion = create(sLang, xConfig, xArgs.install, xArgs.javascript, )
+            sVersion = create(sLang, xConfig, xArgs.install, xArgs.javascript, xArgs.use_cache)
 
             # tests
             if xArgs.tests or xArgs.perf or xArgs.perf_memo:
                 print("> Running tests")
                 try: