pass file modification times from icl module and dcl modules to backend

git-svn-id: https://svn.cs.ru.nl/repos/clean-compiler/trunk@808 1f8540f1-abd5-4d5b-9d24-4c5ce8603e2d

15 files changed, 98 insertions, 81 deletions

diff --git a/frontend/check.icl b/frontend/check.icl
index 3c8cf6b..1ddda1f 100644
--- a/frontend/check.icl
+++ b/frontend/check.icl
@@ -1582,7 +1582,7 @@ checkModule m icl_global_function_range fun_defs n_functions_and_macros_in_dcl_m
 	# icl_instance_range = {ir_from = first_inst_index, ir_to = nr_of_functions}
 	
 	// llslsls CheckState
-	= check_module2 mod_name mod_imported_objects mod_imports mod_type icl_global_function_range icl_instance_range nr_of_functions n_functions_and_macros_in_dcl_modules optional_pre_def_mod local_defs icl_functions init_dcl_modules cdefs sizes heaps cs
+	= check_module2 mod_name m.mod_modification_time mod_imported_objects mod_imports mod_type icl_global_function_range icl_instance_range nr_of_functions n_functions_and_macros_in_dcl_modules optional_pre_def_mod local_defs icl_functions init_dcl_modules cdefs sizes heaps cs
 
 check_module1 {mod_type,mod_name,mod_imports,mod_imported_objects,mod_defs = cdefs} icl_global_function_range fun_defs optional_dcl_mod optional_pre_def_mod scanned_modules dcl_modules functions_and_macros dcl_module_n_in_cache predef_symbols symbol_table err_file
 	# error = {ea_file = err_file, ea_loc = [], ea_ok = True }
@@ -1750,12 +1750,12 @@ add_function_conversion_table dcl_to_icl_function_conversions main_dcl_module_n
 			# dcl_modules = {dcl_modules & [main_dcl_module_n].dcl_conversions=Yes conversion_table}
 			-> dcl_modules
 
-check_module2 :: Ident [.ImportedObject] .[Import ImportDeclaration] .ModuleKind !.IndexRange !.IndexRange !Int !Int 
+check_module2 :: Ident {#Char} [.ImportedObject] .[Import ImportDeclaration] .ModuleKind !.IndexRange !.IndexRange !Int !Int 
 				(Optional (Module a)) [Declaration] *{#FunDef} *{#DclModule} (CollectedDefinitions ClassInstance IndexRange) 
 				*{#.Int} *Heaps *CheckState 
 			-> (!Bool,.IclModule,!.{#DclModule},.{!Group},!Optional {#Int},!.{#FunDef},!Int,!.Heaps,!.{#PredefinedSymbol},
 				!.Heap SymbolTableEntry,!.File,[String]);
-check_module2 mod_name mod_imported_objects mod_imports mod_type icl_global_function_range icl_instance_range nr_of_functions n_functions_and_macros_in_dcl_modules optional_pre_def_mod local_defs icl_functions init_dcl_modules cdefs sizes heaps cs
+check_module2 mod_name mod_modification_time mod_imported_objects mod_imports mod_type icl_global_function_range icl_instance_range nr_of_functions n_functions_and_macros_in_dcl_modules optional_pre_def_mod local_defs icl_functions init_dcl_modules cdefs sizes heaps cs
 	# (main_dcl_module_n,cs)=cs!cs_x.x_main_dcl_module_n
 	  (icl_sizes_without_added_dcl_defs, sizes) = memcpy sizes
 	  (copied_dcl_defs, dcl_modules, local_defs, cdefs, icl_sizes, cs)
@@ -1910,7 +1910,7 @@ check_module2 mod_name mod_imported_objects mod_imports mod_type icl_global_func
 			  	 			  com_instance_defs = class_instances }	  			  
 		  icl_mod		= { 	icl_name = mod_name, icl_functions = icl_functions, icl_common = icl_common, icl_instances = icl_instances, icl_specials = icl_specials,
 								icl_imported_objects = mod_imported_objects, icl_used_module_numbers = imported_module_numbers, icl_copied_from_dcl = copied_dcl_defs,
-	  			  				icl_import = icl_imported }
+	  			  				icl_import = icl_imported,  icl_modification_time = mod_modification_time}
 
 		  heaps = { heaps & hp_var_heap = var_heap, hp_expression_heap = expr_heap, hp_type_heaps = {hp_type_heaps & th_vars = th_vars}}
 
@@ -1929,7 +1929,7 @@ check_module2 mod_name mod_imported_objects mod_imports mod_type icl_global_func
 		  					icl_instances = icl_instance_range,
 		  					icl_specials = {ir_from = nr_of_functions, ir_to = nr_of_functions},
 							icl_imported_objects = mod_imported_objects, icl_used_module_numbers = imported_module_numbers, icl_copied_from_dcl = copied_dcl_defs,
-	    		  			icl_import = icl_imported }
+	    		  			icl_import = icl_imported, icl_modification_time = mod_modification_time}
 		= (False, icl_mod, dcl_modules, {}, No, {}, cs_x.x_main_dcl_module_n,heaps, cs_predef_symbols, cs_symbol_table, cs_error.ea_file, directly_imported_dcl_modules)
 	where
 		check_start_rule mod_kind mod_name {ir_from, ir_to} cs=:{cs_predef_symbols,cs_symbol_table,cs_x}
@@ -2204,7 +2204,7 @@ makeElemTypeOfArrayFunctionStrict st=:{st_args,st_result} me_offset offset_table
 					st_result = { st_result &  at_type = TA tuple [{ elem & at_annotation = AN_Strict } : res_array]}}
 		= st
 
-initialDclModule ({mod_name, mod_defs=mod_defs=:{def_funtypes,def_macros}, mod_type}, sizes, all_defs) module_n
+initialDclModule ({mod_name, mod_modification_time, mod_defs=mod_defs=:{def_funtypes,def_macros}, mod_type}, sizes, all_defs) module_n
 	# dcl_common= createCommonDefinitions mod_defs
 	= 	{	dcl_name			= mod_name
 		,	dcl_functions		= { function \\ function <- mod_defs.def_funtypes }
@@ -2226,6 +2226,7 @@ initialDclModule ({mod_name, mod_defs=mod_defs=:{def_funtypes,def_macros}, mod_t
 								_			-> False
 */
 		,	dcl_module_kind	= mod_type
+		,	dcl_modification_time = mod_modification_time
 // ... RWS
 		,	dcl_imported_module_numbers = EndNumbers
 		}
diff --git a/frontend/checksupport.dcl b/frontend/checksupport.dcl
index f1baa74..6e6688f 100644
--- a/frontend/checksupport.dcl
+++ b/frontend/checksupport.dcl
@@ -98,6 +98,9 @@ cConversionTableSize	:== 9 // AA
 	,	icl_imported_objects	:: ![ImportedObject]
 	,	icl_used_module_numbers :: !NumberSet
 	,	icl_copied_from_dcl 	:: !CopiedDefinitions
+// RWS ...
+	,	icl_modification_time	:: !{#Char}
+// ... RWS
 	}
 
 ::	DclModule =
@@ -112,6 +115,7 @@ cConversionTableSize	:== 9 // AA
 	,	dcl_conversions		:: !Optional ConversionTable
 // RWS ...	,	dcl_is_system		:: !Bool
 	,	dcl_module_kind		:: !ModuleKind
+	,	dcl_modification_time:: !{#Char}
 // ... RWS
 	,	dcl_imported_module_numbers :: !NumberSet
 	}
diff --git a/frontend/checksupport.icl b/frontend/checksupport.icl
index 3320f1a..223da52 100644
--- a/frontend/checksupport.icl
+++ b/frontend/checksupport.icl
@@ -111,6 +111,9 @@ where
 	,	icl_imported_objects	:: ![ImportedObject]
 	,	icl_used_module_numbers :: !NumberSet
 	,	icl_copied_from_dcl 	:: !CopiedDefinitions
+// RWS ...
+	,	icl_modification_time	:: !{#Char}
+// ... RWS
 	}
 
 ::	DclModule =
@@ -125,6 +128,7 @@ where
 	,	dcl_conversions		:: !Optional ConversionTable
 // RWS ...	,	dcl_is_system		:: !Bool
 	,	dcl_module_kind		:: !ModuleKind
+	,	dcl_modification_time:: !{#Char}
 // ... RWS
 	,	dcl_imported_module_numbers :: !NumberSet
 	}
diff --git a/frontend/frontend.dcl b/frontend/frontend.dcl
index 7751e3d..84fdf3b 100644
--- a/frontend/frontend.dcl
+++ b/frontend/frontend.dcl
@@ -31,5 +31,5 @@ import checksupport, transform, overloading
 	|	FrontEndPhaseConvertModules
 	|	FrontEndPhaseAll
 
-frontEndInterface :: !FrontEndOptions !Ident !SearchPaths !{#DclModule} !{#FunDef} !(Optional Bool) !*PredefinedSymbols !*HashTable !*Files !*File !*File !*File (!Optional !*File) !*Heaps
+frontEndInterface :: !FrontEndOptions !Ident !SearchPaths !{#DclModule} !{#FunDef} !(Optional Bool) !*PredefinedSymbols !*HashTable (ModTimeFunction *Files) !*Files !*File !*File !*File (!Optional !*File) !*Heaps
   	-> ( !Optional *FrontEndSyntaxTree,!*{# FunDef },!{#DclModule},!Int,!Int,!*PredefinedSymbols, !*HashTable, !*Files, !*File, !*File, !*File, !Optional !*File, !*Heaps) 
diff --git a/frontend/frontend.icl b/frontend/frontend.icl
index 1cd3a5a..24fd0a4 100644
--- a/frontend/frontend.icl
+++ b/frontend/frontend.icl
@@ -83,20 +83,20 @@ frontSyntaxTree cached_functions_and_macros cached_dcl_mods n_functions_and_macr
 
 // import StdDebug
 
-frontEndInterface :: !FrontEndOptions !Ident !SearchPaths !{#DclModule} !{#FunDef} !(Optional Bool) !*PredefinedSymbols !*HashTable !*Files !*File !*File !*File (!Optional !*File) !*Heaps
+frontEndInterface :: !FrontEndOptions !Ident !SearchPaths !{#DclModule} !{#FunDef} !(Optional Bool) !*PredefinedSymbols !*HashTable (ModTimeFunction *Files) !*Files !*File !*File !*File (!Optional !*File) !*Heaps
   	-> ( !Optional *FrontEndSyntaxTree,!*{# FunDef },!{#DclModule},!Int,!Int,!*PredefinedSymbols, !*HashTable, !*Files, !*File, !*File, !*File, !Optional !*File, !*Heaps) 
-frontEndInterface options mod_ident search_paths cached_dcl_modules functions_and_macros list_inferred_types predef_symbols hash_table files error io out tcl_file heaps 
+frontEndInterface options mod_ident search_paths cached_dcl_modules functions_and_macros list_inferred_types predef_symbols hash_table modtimefunction files error io out tcl_file heaps 
 // 	# files = trace_n ("Compiling "+++mod_ident.id_name) files
 
 	# (ok, mod, hash_table, error, predef_symbols, files)
-		= wantModule cWantIclFile mod_ident NoPos options.feo_generics(hash_table /* ---> ("Parsing:", mod_ident)*/) error search_paths predef_symbols files
+		= wantModule cWantIclFile mod_ident NoPos options.feo_generics(hash_table /* ---> ("Parsing:", mod_ident)*/) error search_paths predef_symbols modtimefunction files
 	| not ok
 		= (No,{},{},0,0,predef_symbols, hash_table, files, error, io, out, tcl_file, heaps)
 
 	# cached_module_idents = [dcl_mod.dcl_name \\ dcl_mod<-:cached_dcl_modules]
 	# (nr_of_chached_functions_and_macros, functions_and_macros) = usize functions_and_macros
 	# (ok, mod, global_fun_range, mod_functions, optional_dcl_mod, modules, dcl_module_n_in_cache,n_functions_and_macros_in_dcl_modules,hash_table, error, predef_symbols, files)
-		= scanModule (mod -*-> "Scanning") cached_module_idents nr_of_chached_functions_and_macros options.feo_generics hash_table error search_paths predef_symbols files
+		= scanModule (mod -*-> "Scanning") cached_module_idents nr_of_chached_functions_and_macros options.feo_generics hash_table error search_paths predef_symbols modtimefunction files
 	/* JVG: */
 //	# hash_table = {hash_table & hte_entries={}}
 	# hash_table = remove_icl_symbols_from_hash_table hash_table
@@ -275,11 +275,11 @@ frontEndInterface options mod_ident search_paths cached_dcl_modules functions_an
 //	# (fun_defs,out,var_heap,predef_symbols) = sa components main_dcl_module_n dcl_mods fun_defs out var_heap predef_symbols;
 
 	# heaps = {hp_var_heap = var_heap, hp_expression_heap=expression_heap, hp_type_heaps=type_heaps}
-	#! 	fe ={	fe_icl =
+	# 	fe ={	fe_icl =
 //							 {icl_mod & icl_functions=fun_defs }
 							 {icl_functions=fun_defs,icl_instances=icl_instances,icl_specials=icl_specials,icl_common=icl_common,icl_import=icl_import,
 							 icl_name=icl_name,icl_imported_objects=icl_imported_objects,icl_used_module_numbers=icl_used_module_numbers,
-							 icl_copied_from_dcl=icl_copied_from_dcl}
+							 icl_copied_from_dcl=icl_copied_from_dcl,icl_modification_time=icl_mod.icl_modification_time}
 
 			,	fe_dcls = dcl_mods
 			,	fe_components = components
diff --git a/frontend/main.icl b/frontend/main.icl
index e1795d4..087046a 100644
--- a/frontend/main.icl
+++ b/frontend/main.icl
@@ -165,10 +165,14 @@ compileModule mod_name dcl_cache ms
 	  dcl_cache = {dcl_cache & hash_table=hash_table}
 	= loadModule mod_ident.boxed_ident dcl_cache ms
 
+dummyModTime :: {#Char} .f -> ({#Char}, .f)
+dummyModTime _ f
+	=	("", f)
+
 loadModule :: Ident *DclCache *MainState -> *(!Optional InterMod,!*DclCache,!*MainState);
 loadModule mod_ident {dcl_modules,functions_and_macros,predef_symbols,hash_table,heaps} ms=:{ms_files,ms_error,ms_io,ms_out,ms_paths}
 	# (optional_syntax_tree,cached_functions_and_macros,cached_dcl_mods,_,main_dcl_module_n,predef_symbols, hash_table, ms_files, ms_error, ms_io, ms_out,_,heaps)
-		= frontEndInterface { feo_up_to_phase = FrontEndPhaseAll,feo_generics = False} mod_ident {sp_locations = [], sp_paths = ms_paths} dcl_modules functions_and_macros No predef_symbols hash_table ms_files ms_error ms_io ms_out No heaps
+		= frontEndInterface { feo_up_to_phase = FrontEndPhaseAll, feo_generics = False, feo_fusion = False} mod_ident {sp_locations = [], sp_paths = ms_paths} dcl_modules functions_and_macros No predef_symbols hash_table dummyModTime ms_files ms_error ms_io ms_out No heaps
 	# ms = {ms & ms_files=ms_files, ms_error=ms_error,ms_io=ms_io,ms_out=ms_out}
 	= case optional_syntax_tree of
 		Yes {fe_icl={/*icl_functions,*/icl_used_module_numbers}, fe_dcls, fe_dclIclConversions, fe_iclDclConversions}
diff --git a/frontend/parse.dcl b/frontend/parse.dcl
index 6f0659f..ac78a2f 100644
--- a/frontend/parse.dcl
+++ b/frontend/parse.dcl
@@ -10,5 +10,5 @@ import syntax, hashtable, scanner, predef
 cWantIclFile :== True	
 cWantDclFile :== False	
 
-wantModule :: !Bool !Ident !Position !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols !*Files
+wantModule :: !Bool !Ident !Position !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols (ModTimeFunction *Files) !*Files
 	-> (!Bool, !ParsedModule, !*HashTable, !*File, !*PredefinedSymbols, !*Files)
diff --git a/frontend/parse.icl b/frontend/parse.icl
index 2955d9c..17cee43 100644
--- a/frontend/parse.icl
+++ b/frontend/parse.icl
@@ -289,23 +289,23 @@ isClassOrInstanceDefsContext context	:== context bitand cClassOrInstanceDefsCont
 cWantIclFile :== True	
 cWantDclFile :== False	
 
-wantModule :: !Bool !Ident !Position !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols !*Files
+wantModule :: !Bool !Ident !Position !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols (ModTimeFunction *Files) !*Files
 	-> (!Bool, !ParsedModule, !*HashTable, !*File, !*PredefinedSymbols, !*Files)
-wantModule iclmodule file_id=:{id_name} import_file_position support_generics hash_table error searchPaths pre_def_symbols files
-	= case openScanner file_name searchPaths files of
-		(Yes scanState, files)
+wantModule iclmodule file_id=:{id_name} import_file_position support_generics hash_table error searchPaths pre_def_symbols modtimefunction files
+	= case openScanner file_name searchPaths modtimefunction files of
+		(Yes (scanState, modification_time), files)
 			# hash_table=set_hte_mark (if iclmodule 1 0) hash_table
-			# (ok,mod,hash_table,file,pre_def_symbols,files) = initModule file_name scanState hash_table error pre_def_symbols files
+			# (ok,mod,hash_table,file,pre_def_symbols,files) = initModule file_name modification_time scanState hash_table error pre_def_symbols files
 			# hash_table=set_hte_mark 0 hash_table
 			->(ok,mod,hash_table,file,pre_def_symbols,files)
 		(No, files)
-			-> let mod = { mod_name = file_id, mod_type = MK_None, mod_imports = [], mod_imported_objects = [], mod_defs = [] } in
+			-> let mod = { mod_name = file_id,  mod_modification_time = "", mod_type = MK_None, mod_imports = [], mod_imported_objects = [], mod_defs = [] } in
 			  (False, mod, hash_table, error <<< "Error " <<< import_file_position <<< ": "  <<< file_name <<< " could not be imported\n", pre_def_symbols, files)
 where
 	file_name = if iclmodule (id_name +++ ".icl") (id_name +++ ".dcl")
-	initModule :: String ScanState !*HashTable !*File !*PredefinedSymbols *Files
+	initModule :: String String ScanState !*HashTable !*File !*PredefinedSymbols *Files
 				-> (!Bool, !ParsedModule, !*HashTable, !*File, !*PredefinedSymbols, !*Files)
-	initModule file_name scanState hash_table error pre_def_symbols files
+	initModule file_name modification_time scanState hash_table error pre_def_symbols files
 		# (succ, mod_type, mod_name, scanState) = try_module_header iclmodule scanState
 		| succ
 			# pState				=	{ ps_scanState = scanState
@@ -327,7 +327,7 @@ where
 			  defs = if (ParseOnly && id_name <> "StdOverloaded" && id_name <> "StdArray" && id_name <> "StdEnum" && id_name <> "StdBool" && id_name <> "StdDynamics" && id_name <> "StdGeneric")
 						[PD_Import imports \\ PD_Import imports <- defs]
 						defs
-			  mod					= { mod_name = mod_ident, mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs = defs }
+			  mod					= { mod_name = mod_ident, mod_modification_time = modification_time, mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs = defs }
 			= ( ps_error.pea_ok
 			  , mod, ps_hash_table
 			  , ps_error.pea_file
@@ -336,7 +336,7 @@ where
 			  )
 		// otherwise // ~ succ
 		# ({fp_line}, scanState) = getPosition scanState
-		  mod = { mod_name = file_id, mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs = [] }
+		  mod = { mod_name = file_id,  mod_modification_time = modification_time, mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs = [] }
 		= (False, mod, hash_table, error <<< "Error [" <<< file_name <<< ',' <<< fp_line <<< "]: incorrect module header",
 			pre_def_symbols, closeScanner scanState files)
 	where
diff --git a/frontend/postparse.dcl b/frontend/postparse.dcl
index e0fa317..95d9b21 100644
--- a/frontend/postparse.dcl
+++ b/frontend/postparse.dcl
@@ -4,5 +4,5 @@ import StdEnv
 
 import syntax, parse, predef
 
-scanModule :: !ParsedModule ![Ident] !Int !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols !*Files
+scanModule :: !ParsedModule ![Ident] !Int !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols (ModTimeFunction *Files) !*Files
 	-> (!Bool, !ScannedModule, !IndexRange, ![FunDef], !Optional ScannedModule, ![ScannedModule],!Int,!Int,!*HashTable, !*File, !*PredefinedSymbols, !*Files)
diff --git a/frontend/postparse.icl b/frontend/postparse.icl
index 112b02b..b6f7f64 100644
--- a/frontend/postparse.icl
+++ b/frontend/postparse.icl
@@ -1002,25 +1002,25 @@ transformArrayDenot exprs pi
 			[{bind_dst=toParsedExpr i pi, bind_src=expr} \\ expr <- exprs & i <- [0..]]
 			pi
 
-scanModules :: [ParsedImport] [ScannedModule] [Ident] SearchPaths Bool *Files *CollectAdmin -> (Bool, [ScannedModule], *Files, *CollectAdmin)
-scanModules [] parsed_modules cached_modules searchPaths support_generics files ca
+scanModules :: [ParsedImport] [ScannedModule] [Ident] SearchPaths Bool (ModTimeFunction *Files) *Files *CollectAdmin -> (Bool, [ScannedModule], *Files, *CollectAdmin)
+scanModules [] parsed_modules cached_modules searchPaths support_generics _ files ca
 	= (True, parsed_modules, files, ca)
-scanModules [{import_module,import_symbols,import_file_position} : mods] parsed_modules cached_modules searchPaths support_generics files ca
+scanModules [{import_module,import_symbols,import_file_position} : mods] parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 	| in_cache import_module cached_modules
-		= scanModules mods parsed_modules cached_modules searchPaths support_generics files ca
+		= scanModules mods parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 	# (found_module,mod_type) = try_to_find import_module parsed_modules
 	| found_module
 		= case mod_type of
 			MK_NoMainDcl
 				# ca = postParseError import_file_position ("main module \'"+++import_module.id_name+++"\' does not have a definition module") ca
-				# (_,parsed_modules,files,ca) = scanModules mods parsed_modules cached_modules searchPaths support_generics files ca
+				# (_,parsed_modules,files,ca) = scanModules mods parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 				-> (False,parsed_modules,files,ca)
 			_
-				-> scanModules mods parsed_modules cached_modules searchPaths support_generics files ca
+				-> scanModules mods parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 		# (succ, parsed_modules, files, ca)
-				= parseAndScanDclModule import_module import_file_position parsed_modules cached_modules searchPaths support_generics files ca
+				= parseAndScanDclModule import_module import_file_position parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 		  (mods_succ, parsed_modules, files, ca)
-		  		= scanModules mods parsed_modules cached_modules searchPaths support_generics files ca
+		  		= scanModules mods parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 		= (succ && mods_succ, parsed_modules, files, ca)
 where
 	in_cache mod_id []
@@ -1039,26 +1039,26 @@ where
 			= try_to_find mod_id pmods
 
 MakeEmptyModule name mod_type
-	:== { mod_name = name, mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs =
+	:== { mod_name = name, mod_modification_time = "", mod_type = mod_type, mod_imports = [], mod_imported_objects = [], mod_defs =
 				{	def_types = [], def_constructors = [], def_selectors = [], def_classes = [], def_macros = { ir_from = 0, ir_to = 0 },
 					def_members = [], def_funtypes = [], def_instances = [], /* AA */ def_generics = [] } }
 
-parseAndScanDclModule :: !Ident !Position ![ScannedModule] ![Ident] !SearchPaths !Bool !*Files !*CollectAdmin
+parseAndScanDclModule :: !Ident !Position ![ScannedModule] ![Ident] !SearchPaths !Bool (ModTimeFunction *Files) !*Files !*CollectAdmin
 	-> *(!Bool, ![ScannedModule], !*Files, !*CollectAdmin)
-parseAndScanDclModule dcl_module import_file_position parsed_modules cached_modules searchPaths support_generics files ca
+parseAndScanDclModule dcl_module import_file_position parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 	# {ca_error, ca_fun_count, ca_rev_fun_defs, ca_predefs, ca_u_predefs, ca_hash_table}
 		= ca
 	  hash_table = ca_hash_table
 	  pea_file = ca_error.pea_file
 	  predefs = ca_u_predefs
-	# (parse_ok, mod, hash_table, err_file, predefs, files) = wantModule cWantDclFile dcl_module import_file_position support_generics hash_table pea_file searchPaths predefs files
+	# (parse_ok, mod, hash_table, err_file, predefs, files) = wantModule cWantDclFile dcl_module import_file_position support_generics hash_table pea_file searchPaths predefs modtimefunction files
 	# ca = {ca_hash_table=hash_table, ca_error={pea_file=err_file,pea_ok=True}, ca_u_predefs=predefs, ca_fun_count=ca_fun_count, ca_rev_fun_defs=ca_rev_fun_defs, ca_predefs=ca_predefs}
 	| parse_ok
-		= scan_dcl_module mod parsed_modules searchPaths files ca
+		= scan_dcl_module mod parsed_modules searchPaths modtimefunction files ca
 		= (False, [MakeEmptyModule mod.mod_name MK_None: parsed_modules], files, ca)
 where
-	scan_dcl_module :: ParsedModule [ScannedModule] !SearchPaths *Files *CollectAdmin -> (Bool, [ScannedModule], *Files, *CollectAdmin)
-	scan_dcl_module mod=:{mod_defs = pdefs} parsed_modules searchPaths files ca
+	scan_dcl_module :: ParsedModule [ScannedModule] !SearchPaths (ModTimeFunction *Files) *Files *CollectAdmin -> (Bool, [ScannedModule], *Files, *CollectAdmin)
+	scan_dcl_module mod=:{mod_defs = pdefs} parsed_modules searchPaths modtimefunction files ca
 		# (_, defs, imports, imported_objects, ca)
 			=	reorganiseDefinitions False pdefs 0 0 0 0 ca
 	  	  (macro_defs, ca)
@@ -1070,12 +1070,12 @@ where
 		  mod
 		  	=	{ mod & mod_imports = imports, mod_imported_objects = imported_objects, mod_defs = { defs & def_macros = range }}
 		  (import_ok, parsed_modules, files, ca)
-		  		= scanModules imports [mod : parsed_modules] cached_modules searchPaths support_generics files ca
+		  		= scanModules imports [mod : parsed_modules] cached_modules searchPaths support_generics modtimefunction files ca
 		= (pea_ok && import_ok, parsed_modules, files, ca)
 
-scanModule :: !ParsedModule ![Ident] !Int !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols !*Files
+scanModule :: !ParsedModule ![Ident] !Int !Bool !*HashTable !*File !SearchPaths !*PredefinedSymbols (ModTimeFunction *Files) !*Files
 	-> (!Bool, !ScannedModule, !IndexRange, ![FunDef], !Optional ScannedModule, ![ScannedModule],!Int,!Int,!*HashTable, !*File, !*PredefinedSymbols, !*Files)
-scanModule mod=:{mod_name,mod_type,mod_defs = pdefs} cached_modules first_new_function_or_macro_index support_generics hash_table err_file searchPaths predefs files
+scanModule mod=:{mod_name,mod_type,mod_defs = pdefs} cached_modules first_new_function_or_macro_index support_generics hash_table err_file searchPaths predefs modtimefunction files
 	# (predefIdents, predefs) = SelectPredefinedIdents predefs
 	# ca =	{	ca_error		= {pea_file = err_file, pea_ok = True}
 			,	ca_fun_count	= first_new_function_or_macro_index
@@ -1088,9 +1088,9 @@ scanModule mod=:{mod_name,mod_type,mod_defs = pdefs} cached_modules first_new_fu
 	  (reorganise_icl_ok, ca) = ca!ca_error.pea_ok
 
 	  (import_dcl_ok, optional_parsed_dcl_mod,dcl_module_n,parsed_modules, cached_modules,files, ca)
-	  		= scan_main_dcl_module mod_name mod_type files ca
+	  		= scan_main_dcl_module mod_name mod_type modtimefunction files ca
 	  (import_dcls_ok, parsed_modules, files, ca)
-	  		= scanModules imports parsed_modules cached_modules searchPaths support_generics files ca
+	  		= scanModules imports parsed_modules cached_modules searchPaths support_generics modtimefunction files ca
 
 	  (pea_dcl_ok,optional_dcl_mod,ca) =  collect_main_dcl_module optional_parsed_dcl_mod dcl_module_n ca
 
@@ -1122,12 +1122,12 @@ scanModule mod=:{mod_name,mod_type,mod_defs = pdefs} cached_modules first_new_fu
 //	  (pre_def_mod, ca_u_predefs) = buildPredefinedModule ca_u_predefs
 	= (reorganise_icl_ok && pea_ok && import_dcl_ok && import_dcls_ok, mod, fun_range, reverse ca_rev_fun_defs, optional_dcl_mod, /*pre_def_mod,*/ modules, dcl_module_n,n_functions_and_macros_in_dcl_modules,hash_table, err_file, ca_u_predefs, files)
 where
-	scan_main_dcl_module :: Ident ModuleKind *Files *CollectAdmin -> (!Bool,!Optional (Module (CollectedDefinitions (ParsedInstance FunDef) [FunDef])),!Int,![ScannedModule],![Ident],!*Files,!*CollectAdmin)
-	scan_main_dcl_module mod_name MK_Main files ca
+	scan_main_dcl_module :: Ident ModuleKind (ModTimeFunction *Files) *Files *CollectAdmin -> (!Bool,!Optional (Module (CollectedDefinitions (ParsedInstance FunDef) [FunDef])),!Int,![ScannedModule],![Ident],!*Files,!*CollectAdmin)
+	scan_main_dcl_module mod_name MK_Main _ files ca
 		= (True, No,NoIndex,[MakeEmptyModule mod_name MK_NoMainDcl], cached_modules,files, ca)
-	scan_main_dcl_module mod_name MK_None files ca
+	scan_main_dcl_module mod_name MK_None _ files ca
 		= (True, No,NoIndex,[], cached_modules,files, ca)
-	scan_main_dcl_module mod_name kind files ca
+	scan_main_dcl_module mod_name kind modtimefunction files ca
 		# module_n_in_cache = in_cache 0 cached_modules;
 			with
 			in_cache module_n []
@@ -1142,7 +1142,7 @@ where
 		  hash_table = ca_hash_table
 		  pea_file = ca_error.pea_file
 		  predefs = ca_u_predefs
-		# (parse_ok, mod, hash_table, err_file, predefs, files) = wantModule cWantDclFile mod_name NoPos support_generics hash_table pea_file searchPaths predefs files
+		# (parse_ok, mod, hash_table, err_file, predefs, files) = wantModule cWantDclFile mod_name NoPos support_generics hash_table pea_file searchPaths predefs modtimefunction files
 		# ca = {ca_hash_table=hash_table, ca_error={pea_file=err_file,pea_ok=True}, ca_u_predefs=predefs, ca_fun_count=ca_fun_count, ca_rev_fun_defs=ca_rev_fun_defs, ca_predefs=ca_predefs}
 		| not parse_ok
 			= (False, No,NoIndex, [],cached_modules, files, ca)
@@ -1150,7 +1150,7 @@ where
 			# (_, defs, imports, imported_objects, ca) =	reorganiseDefinitions False pdefs 0 0 0 0 ca
 			# mod  = { mod & mod_imports = imports, mod_imported_objects = imported_objects, mod_defs = defs}
 			# cached_modules = [mod.mod_name:cached_modules]
-			# (import_ok, parsed_modules, files, ca) = scanModules imports [] cached_modules searchPaths support_generics files ca
+			# (import_ok, parsed_modules, files, ca) = scanModules imports [] cached_modules searchPaths support_generics modtimefunction files ca
 			= (import_ok, Yes mod, NoIndex,parsed_modules, cached_modules,files, ca)
 
 	collect_main_dcl_module (Yes mod=:{mod_defs=defs}) dcl_module_n ca
diff --git a/frontend/predef.icl b/frontend/predef.icl
index 43d33ac..bc13c2b 100644
--- a/frontend/predef.icl
+++ b/frontend/predef.icl
@@ -440,7 +440,7 @@ buildPredefinedModule pre_def_symbols
 	  (type_defs, cons_defs, pre_def_symbols)	= add_tuple_defs pre_mod_id MaxTupleArity [array_def,strict_def,unboxed_def] [] pre_def_symbols
 	  alias_dummy_type = make_identity_fun_type alias_dummy_symb.pds_ident type_var // MW++
 	  (class_def, member_def, pre_def_symbols) = make_TC_class_def pre_def_symbols
-	= ({ mod_name = pre_mod_id, mod_type = MK_System, mod_imports = [],  mod_imported_objects = [],
+	= ({ mod_name = pre_mod_id, mod_modification_time = "", mod_type = MK_System, mod_imports = [],  mod_imported_objects = [],
 		 mod_defs = {
 			def_types = [string_def, list_def,strict_list_def,unboxed_list_def,tail_strict_list_def,strict_tail_strict_list_def,unboxed_tail_strict_list_def,overloaded_list_def : type_defs],
 						def_constructors = [cons_def,strict_cons_def,unboxed_cons_def,tail_strict_cons_def,strict_tail_strict_cons_def,unboxed_tail_strict_cons_def,overloaded_cons_def,
diff --git a/frontend/scanner.dcl b/frontend/scanner.dcl
index dd25d2c..b20e43f 100644
--- a/frontend/scanner.dcl
+++ b/frontend/scanner.dcl
@@ -3,10 +3,15 @@ definition module scanner
 import StdEnv, general
 
 // RWS Proof ... ::	SearchPaths	:== [String]
+
 :: SearchPaths = 
 	{ sp_locations   :: [(String, String)]       // (module, path)
 	, sp_paths       :: [String]
 	}
+
+:: ModTimeFunction f
+	:== ({#Char} !f -> *(!{#Char}, !f))
+
 // ... RWS
 
 ::	* ScanState
@@ -139,7 +144,7 @@ instance replaceToken ScanState
 class getPosition state :: !*state -> (!FilePosition,!*state)  // Position of current Token (or Char)
 instance getPosition ScanState
 
-openScanner :: !String !SearchPaths !*Files -> (!Optional ScanState, !*Files)
+openScanner :: !String !SearchPaths (ModTimeFunction *Files) !*Files -> (!Optional (ScanState, {#Char}), !*Files) // state, file time
 closeScanner :: !ScanState !*Files -> *Files
 
 setUseLayout :: !Bool !ScanState -> ScanState
diff --git a/frontend/scanner.icl b/frontend/scanner.icl
index 911a127..7a5a204 100644
--- a/frontend/scanner.icl
+++ b/frontend/scanner.icl
@@ -9,6 +9,10 @@ from utilities import revCharListToString, isSpecialChar
 	{ sp_locations   :: [(String, String)]       // (module, path)
 	, sp_paths       :: [String]
 	}
+
+:: ModTimeFunction f
+	:== ({#Char} !f -> *(!{#Char}, !f))
+
 // ... RWS
 
 ::	*ScanState = ScanState !RScanState
@@ -1467,12 +1471,12 @@ where
 	toString NoAssoc	= "infix "
 	
 
-openScanner :: !String !SearchPaths !*Files -> (!Optional ScanState, !*Files)
-openScanner file_name searchPaths files
-	= case fopenInSearchPaths file_name searchPaths FReadData files of
+openScanner :: !String !SearchPaths (ModTimeFunction *Files) !*Files -> (!Optional (ScanState, {#Char}), !*Files) // state, file time
+openScanner file_name searchPaths modtimefunction files
+	= case fopenInSearchPaths file_name searchPaths FReadData modtimefunction files of
 		(No, files)
 			->	(No, files)
-		(Yes file, files)
+		(Yes (file, time), files)
 			->  (Yes (ScanState {	ss_input 		= Input
 												{ inp_stream		= InFile file
 									 			, inp_filename		= file_name
@@ -1482,48 +1486,41 @@ openScanner file_name searchPaths files
 						,	ss_offsides		=	[(1,False)] // to generate offsides between global definitions
 						,	ss_scanOptions	=	0
 						,	ss_tokenBuffer	=	Buffer0
-						})
+						}, time)
 				, files
 				)
 
-/* RWS Proof ...
-fopenInSearchPaths :: !{#Char} [!{#Char}] !Int !*f -> (Optional *File,!*f) | FileSystem f
-fopenInSearchPaths fileName [] mode f
-	=	(No, f)
-fopenInSearchPaths fileName [path : paths] mode f
-	# (opened, file, f)
-		=	fopen (path + fileName) mode f
-	| opened
-		=	(Yes file, f)
-	// otherwise
-		=	fopenInSearchPaths fileName paths mode f
-*/
-fopenInSearchPaths :: !{#Char} SearchPaths !Int !*f -> (Optional *File,!*f) | FileSystem f
-fopenInSearchPaths fileName searchPaths mode f
+fopenInSearchPaths :: !{#Char} SearchPaths !Int (ModTimeFunction *f) !*f -> (Optional (*File, {#Char}),!*f) | FileSystem f
+fopenInSearchPaths fileName searchPaths mode modtimefunction f
 	# filtered_locations
 		=	filter (\(moduleName,path) -> moduleName == fileName) searchPaths.sp_locations
 	| isEmpty filtered_locations
-		=	fopenAnywhereInSearchPaths fileName searchPaths.sp_paths mode f
+		=	fopenAnywhereInSearchPaths fileName searchPaths.sp_paths mode modtimefunction f
 	# (_, path)
 		=	hd filtered_locations
 	# (opened, file, f)
 		=	fopen (path + fileName) mode f
 	| opened
-		=	(Yes file, f)
+		=	getModificationTime file path modtimefunction f
 	| otherwise
 		=	(No, f)
 	where
-		fopenAnywhereInSearchPaths :: !{#Char} ![{#Char}] !Int *f -> (Optional *File, !*f) | FileSystem f
-		fopenAnywhereInSearchPaths fileName [] mode f
+		fopenAnywhereInSearchPaths :: !{#Char} ![{#Char}] !Int (ModTimeFunction *f) *f -> (Optional (*File, {#Char}),!*f) | FileSystem f
+		fopenAnywhereInSearchPaths fileName [] _ _ f
 			=	(No, f)
-		fopenAnywhereInSearchPaths fileName [path : paths] mode f
+		fopenAnywhereInSearchPaths fileName [path : paths] mode modtimefunction f
 			# (opened, file, f)
 				=	fopen (path + fileName) mode f
 			| opened
-				=	(Yes file, f)
+				=	getModificationTime file path modtimefunction f
 			// otherwise
-				=	fopenAnywhereInSearchPaths fileName paths mode f
-// ... RWS
+				=	fopenAnywhereInSearchPaths fileName paths mode modtimefunction f
+
+		getModificationTime :: *File {#Char} (ModTimeFunction *f) *f -> (Optional (*File, {#Char}),!*f) | FileSystem f
+		getModificationTime file path modtimefunction f
+			# (time, f)
+				=	modtimefunction (path + fileName) f
+			=	(Yes (file, time), f)
 
 closeScanner :: !ScanState !*Files -> *Files
 closeScanner (ScanState scan_state) files = closeScanner_ scan_state files
diff --git a/frontend/syntax.dcl b/frontend/syntax.dcl
index b3dc90d..f85a457 100644
--- a/frontend/syntax.dcl
+++ b/frontend/syntax.dcl
@@ -83,6 +83,7 @@ instance toString Ident
 	
 ::	Module defs = 
 	{	mod_name		:: !Ident
+	,	mod_modification_time		:: {#Char}
 	,	mod_type		:: !ModuleKind
 	, 	mod_imports		:: ![ParsedImport]
 	,	mod_imported_objects :: ![ImportedObject]
diff --git a/frontend/syntax.icl b/frontend/syntax.icl
index 4427233..ec1de27 100644
--- a/frontend/syntax.icl
+++ b/frontend/syntax.icl
@@ -80,6 +80,7 @@ where toString {import_module} = toString import_module
 	
 ::	Module defs = 
 	{	mod_name		:: !Ident
+	,	mod_modification_time	:: {#Char}
 	,	mod_type		:: !ModuleKind
 	, 	mod_imports		:: ![ParsedImport]
 	,	mod_imported_objects :: ![ImportedObject]