refactoring

util/core.lua

@@ -199,9 +199,8 @@ function public.filter(t, p)
 end
 
 function public.map(t, f)
-	local mapped = M.t
-	for k, v in t do mapped[k] = f(v, k) end
-	return mapped
+	for k, v in t do t[k] = f(v, k) end
+	return t
 end
 
 function public.trim(str)

util/persistence.lua

@@ -50,8 +50,7 @@ function public.read_list(schema, str)
     if str == '' then return t end
     local separator = schema[2]
     local element_type = schema[3]
-    local parts = split(str, separator)
-    return map(parts, function(part)
+    return map(split(str, separator), function(part)
         return read(element_type, part)
     end)
 end
@@ -59,7 +58,7 @@ end
 function public.write_list(schema, list)
     local separator = schema[2]
     local element_type = schema[3]
-    local parts = map(list, function(element)
+    local parts = map(copy(list), function(element)
         return write(element_type, element)
     end)
     return join(parts, separator)