Nullable nonterminals:

  (const_bindings | const_bindings_tail | const_exp | decls | directives |
  format_exp | func_body | hard_exp | implem | imports |
  interf | iter_tail | match_direction | module_names | o_rest |
  obj_names | path | path_tail | paths | pattern |
  pattern_exp | result_exp | sentence | sentences | source |
  source_tail)


The starters of non-terminals:

program ->
  (IMPLEMENTATION | INTERFACE)
interf ->
  (CONST | FUNC_DECL | OBJ_DECL)
implem ->
  (CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL | USE |
  WORD)
imports ->
  (USE)
import ->
  (USE)
module_names ->
  (WORD)
decls ->
  (CONST | FUNC_DECL | OBJ_DECL)
directives ->
  (CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL | WORD)
directive ->
  (CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL | WORD)
trace_all ->
  (TRACE_ALL)
decl ->
  (CONST | FUNC_DECL | OBJ_DECL)
obj_decl ->
  (OBJ_DECL)
obj_names ->
  (WORD)
const_decl ->
  (CONST)
const_bindings ->
  (WORD)
const_bindings_tail ->
  (COMMA)
const_binding ->
  (WORD)
func_decl ->
  (FUNC_DECL)
func_def ->
  (WORD)
func_body ->
  (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LCURL | LPAR | MATCH_DIR |
  NOT | NUMB | REF | TRAP | VAR |
  WORD)
pattern_alt ->
  (LCURL)
sentences ->
  (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WORD)
sentence ->
  (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | TRAP | VAR | WORD)
path ->
  (CHAR | COL | COL_CURL | COMMA | CUT |
  EQL | ERROR | FAIL | FENCE | ITER |
  LANGU | LCURL | LET | LPAR | NOT |
  NUMB | REF | TRAP | VAR | WORD)
path_tail ->
  (COL | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | ITER | LET | NOT |
  TRAP)
iter_tail ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | LET | NOT | TRAP)
o_rest ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | TRAP)
rest ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | TRAP)
source ->
  (CHAR | COL_CURL | LANGU | LCURL | LPAR |
  NUMB | REF | VAR | WORD)
source_tail ->
  (COL_CURL)
alt ->
  (LCURL)
paths ->
  (CHAR | COL | COL_CURL | COMMA | CUT |
  EQL | ERROR | FAIL | FENCE | ITER |
  LANGU | LCURL | LET | LPAR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WORD)
pattern ->
  (CHAR | LPAR | MATCH_DIR | NUMB | REF |
  VAR | WORD)
match_direction ->
  (MATCH_DIR)
pattern_exp ->
  (CHAR | LPAR | NUMB | REF | VAR |
  WORD)
pattern_exp_head ->
  (CHAR | LPAR | NUMB | REF | VAR |
  WORD)
hard_exp ->
  (CHAR | LPAR | NUMB | REF | VAR |
  WORD)
format_exp ->
  (CHAR | LPAR | NUMB | REF | VAR |
  WORD)
result_exp ->
  (CHAR | LANGU | LPAR | NUMB | REF |
  VAR | WORD)
result_exp_head ->
  (CHAR | LANGU | LPAR | NUMB | REF |
  VAR | WORD)
name ->
  (WORD)
const_exp ->
  (CHAR | LPAR | NUMB | REF | WORD)
const_exp_head ->
  (CHAR | LPAR | NUMB | REF | WORD)
static_symbol ->
  (CHAR | NUMB | WORD)


The followers of nullable non-terminals:

interf ->
  ($END)
implem ->
  ($END)
imports ->
  ($END | CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL |
  WORD)
module_names ->
  (SC)
decls ->
  ($END)
directives ->
  ($END)
obj_names ->
  (SC)
const_bindings ->
  (SC)
const_bindings_tail ->
  (SC)
func_body ->
  (SC)
sentences ->
  (RCURL)
sentence ->
  (SC | WITH)
path ->
  (SC | WITH)
path_tail ->
  (SC | WITH)
iter_tail ->
  (SC | WITH)
o_rest ->
  (SC | WITH)
source ->
  (COL | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | ITER | LET | NOT |
  SC | TRAP | WITH)
source_tail ->
  (COL | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | ITER | LET | NOT |
  SC | TRAP | WITH)
paths ->
  (RCURL)
pattern ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | SC | TRAP | WITH)
match_direction ->
  (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | NOT | NUMB |
  REF | SC | TRAP | VAR | WITH |
  WORD)
pattern_exp ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | RPAR | SC | TRAP |
  WITH)
hard_exp ->
  (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | SC | TRAP | WITH)
format_exp ->
  (EQL | SC)
result_exp ->
  (COL | COL_CURL | COMMA | CUT | EQL |
  ERROR | FAIL | FENCE | ITER | LET |
  NOT | RANGU | RPAR | SC | TRAP |
  WITH)
const_exp ->
  (COMMA | RPAR | SC)


*** Annotated grammar ***

program
: (INTERFACE)
     INTERFACE #interf 
| (IMPLEMENTATION)
     IMPLEMENTATION #implem 
;

#interf
: ($END | CONST | FUNC_DECL | OBJ_DECL)
     #decls 
;

#implem
: ($END | CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL |
  USE | WORD)
     #imports #directives 
;

#imports
: ($END | CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL |
  WORD)
     /* empty */
| (USE)
     import #imports 
;

import
: (USE)
     USE #module_names SC 
;

#module_names
: (SC)
     /* empty */
| (WORD)
     name #module_names 
;

#decls
: ($END)
     /* empty */
| (CONST | FUNC_DECL | OBJ_DECL)
     decl SC #decls 
;

#directives
: ($END)
     /* empty */
| (CONST | FUNC_DECL | OBJ_DECL | TRACE_ALL | WORD)
     directive SC #directives 
;

directive
: (CONST | FUNC_DECL | OBJ_DECL)
     decl 
| (WORD)
     func_def 
| (TRACE_ALL)
     trace_all 
;

trace_all
: (TRACE_ALL)
     TRACE_ALL 
;

decl
: (OBJ_DECL)
     obj_decl 
| (CONST)
     const_decl 
| (FUNC_DECL)
     func_decl 
;

obj_decl
: (OBJ_DECL)
     OBJ_DECL #obj_names 
;

#obj_names
: (SC)
     /* empty */
| (WORD)
     name #obj_names 
;

const_decl
: (CONST)
     CONST #const_bindings 
;

#const_bindings
: (SC)
     /* empty */
| (WORD)
     const_binding #const_bindings_tail 
;

#const_bindings_tail
: (SC)
     /* empty */
| (COMMA)
     COMMA const_binding #const_bindings_tail 
;

const_binding
: (WORD)
     name EQL #const_exp 
;

func_decl
: (FUNC_DECL)
     FUNC_DECL name #format_exp EQL #format_exp 
;

func_def
: (WORD)
     name #func_body 
;

#func_body
: (LCURL)
     pattern_alt 
| (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WORD)
     #sentence 
;

pattern_alt
: (LCURL)
     LCURL #sentences RCURL 
;

#sentences
: (RCURL)
     /* empty */
| (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WORD)
     #sentence SC #sentences 
;

#sentence
: (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WITH | WORD)
     #pattern #o_rest 
;

#path
: (CHAR | COL | COL_CURL | COMMA | CUT |
  EQL | ERROR | FAIL | FENCE | ITER |
  LANGU | LCURL | LET | LPAR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WITH | WORD)
     #source #path_tail 
;

#path_tail
: (SC | WITH)
     /* empty */
| (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | TRAP)
     rest 
| (LET)
     LET #hard_exp #o_rest 
| (ITER)
     ITER #source #iter_tail 
| (COL)
     COL #sentence 
;

#iter_tail
: (LET)
     LET #hard_exp #o_rest 
| (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | SC | TRAP | WITH)
     #o_rest 
;

#o_rest
: (SC | WITH)
     /* empty */
| (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | TRAP)
     rest 
;

rest
: (COMMA)
     COMMA #path 
| (FENCE)
     FENCE #path 
| (CUT)
     CUT #path 
| (ERROR)
     ERROR #path 
| (EQL)
     EQL #path 
| (NOT)
     NOT #source #o_rest 
| (FAIL)
     FAIL 
| (TRAP)
     TRAP #path WITH pattern_alt 
;

#source
: (LCURL)
     alt #source_tail 
| (CHAR | COL | COL_CURL | COMMA | CUT |
  EQL | ERROR | FAIL | FENCE | ITER |
  LANGU | LET | LPAR | NOT | NUMB |
  REF | SC | TRAP | VAR | WITH |
  WORD)
     #result_exp #source_tail 
;

#source_tail
: (COL | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | ITER | LET | NOT |
  SC | TRAP | WITH)
     /* empty */
| (COL_CURL)
     COL_CURL pattern_alt #source_tail 
;

alt
: (LCURL)
     LCURL #paths RCURL 
;

#paths
: (RCURL)
     /* empty */
| (CHAR | COL | COL_CURL | COMMA | CUT |
  EQL | ERROR | FAIL | FENCE | ITER |
  LANGU | LCURL | LET | LPAR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WORD)
     #path SC #paths 
;

#pattern
: (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | MATCH_DIR | NOT |
  NUMB | REF | SC | TRAP | VAR |
  WITH | WORD)
     #match_direction #pattern_exp 
;

#match_direction
: (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | NOT | NUMB |
  REF | SC | TRAP | VAR | WITH |
  WORD)
     /* empty */
| (MATCH_DIR)
     MATCH_DIR 
;

#pattern_exp
: (COMMA | CUT | EQL | ERROR | FAIL |
  FENCE | NOT | RPAR | SC | TRAP |
  WITH)
     /* empty */
| (CHAR | LPAR | NUMB | REF | VAR |
  WORD)
     pattern_exp_head #pattern_exp 
;

pattern_exp_head
: (REF)
     REF name 
| (CHAR | NUMB | WORD)
     static_symbol 
| (LPAR)
     LPAR #pattern_exp RPAR 
| (VAR)
     VAR 
;

#hard_exp
: (CHAR | COMMA | CUT | EQL | ERROR |
  FAIL | FENCE | LPAR | NOT | NUMB |
  REF | SC | TRAP | VAR | WITH |
  WORD)
     #pattern_exp 
;

#format_exp
: (CHAR | EQL | LPAR | NUMB | REF |
  SC | VAR | WORD)
     #pattern_exp 
;

#result_exp
: (COL | COL_CURL | COMMA | CUT | EQL |
  ERROR | FAIL | FENCE | ITER | LET |
  NOT | RANGU | RPAR | SC | TRAP |
  WITH)
     /* empty */
| (CHAR | LANGU | LPAR | NUMB | REF |
  VAR | WORD)
     result_exp_head #result_exp 
;

result_exp_head
: (REF)
     REF name 
| (CHAR | NUMB | WORD)
     static_symbol 
| (LPAR)
     LPAR #result_exp RPAR 
| (VAR)
     VAR 
| (LANGU)
     LANGU name #result_exp RANGU 
;

name
: (WORD)
     WORD 
;

#const_exp
: (COMMA | RPAR | SC)
     /* empty */
| (CHAR | LPAR | NUMB | REF | WORD)
     const_exp_head #const_exp 
;

const_exp_head
: (REF)
     REF name 
| (CHAR | NUMB | WORD)
     static_symbol 
| (LPAR)
     LPAR #const_exp RPAR 
;

static_symbol
: (CHAR)
     CHAR 
| (WORD)
     WORD 
| (NUMB)
     NUMB 
;