Begin module interface

First module will be the math module which will provide standard math
functions (sin, cos, ...)

src/language/PEGGrammar.hpp

@@ -54,6 +54,8 @@ struct character : if_must_else< one< '\\' >, escaped_c, ascii::any> {};
 
 struct literal : if_must< one< '"' >, until< one< '"' >, character > > {};
 
+struct import_kw :  TAO_PEGTL_KEYWORD("import") {};
+
 struct LITERAL : seq< literal, ignored >{};
 
 struct REAL : seq< real, ignored >{};
@@ -108,9 +110,14 @@ struct cout_kw : TAO_PEGTL_KEYWORD("cout") {};
 struct cerr_kw : TAO_PEGTL_KEYWORD("cerr") {};
 struct clog_kw : TAO_PEGTL_KEYWORD("clog") {};
 
-struct keywork : sor < basic_type, true_kw, false_kw, do_kw, while_kw, for_kw, if_kw, else_kw, and_kw, or_kw, xor_kw, break_kw, continue_kw, cout_kw, cerr_kw, clog_kw > {};
+struct keywork : sor < basic_type, import_kw, true_kw, false_kw, let_kw, do_kw, while_kw, for_kw, if_kw, else_kw, and_kw, or_kw, xor_kw, break_kw, continue_kw, cout_kw, cerr_kw, clog_kw > {};
+
+struct identifier_minus_keyword : minus< identifier, keywork > {};
 
-struct name : minus< identifier, keywork > {};
+struct module_name : identifier_minus_keyword {};
+struct MODULE_NAME : seq< module_name, ignored > {};
+
+struct name : identifier_minus_keyword {};
 struct NAME : seq< name, ignored > {};
 
 struct right_arrow_kw : seq< one< '-' >, one< '>' > > {};
@@ -269,8 +276,14 @@ struct for_statement_block : seq< sor< braced_instruction_list,
                                       instruction >,
                                  ignored >{};
 
+struct IMPORT : seq< import_kw, ignored >{};
+
+struct import_instruction : if_must< IMPORT, MODULE_NAME , semicol >{};
+struct IMPORT_INSTRUCTION : seq<import_instruction, ignored> {};
+struct import_list : star< IMPORT_INSTRUCTION > {};
+
 struct instruction_list : star< INSTRUCTION >{};
-struct grammar : must<ignored, instruction_list, eof>{};
+struct grammar : must<ignored, import_list, instruction_list, eof>{};
 
 template <typename Rule>
 struct errors : public normal<Rule>
@@ -288,6 +301,11 @@ struct errors : public normal<Rule>
 template <typename Rule>
 inline const std::string errors<Rule>::error_message = "parse error matching "+ internal::demangle< Rule >();
 
+template <>
+inline const std::string errors<language::module_name>::error_message = "parse error, missing module name";
+template <>
+inline const std::string errors<language::MODULE_NAME>::error_message = "parse error, missing module name";
+
 template <>
 inline const std::string errors<language::semicol>::error_message = "parse error, missing ';'";
 template <>