grammar correction : an instruction can be a block

expr_grammar_action.g

@@ -33,7 +33,7 @@ rules
 S -> FUNDEFS SYM_EOF { Node(Tlistglobdef, $1) }
 FUNDEFS -> FUNDEF FUNDEFS { Node(Tfundef, $1)::$2 }
 FUNDEFS -> { [] }
-FUNDEF -> IDENTIFIER SYM_LPARENTHESIS LPARAMS SYM_RPARENTHESIS SYM_LBRACE LINSTRS SYM_RBRACE { [Node(Tfunname, [$1]); Node(Tfunargs, $3); Node(Tfunbody, [$6])] }
+FUNDEF -> IDENTIFIER SYM_LPARENTHESIS LPARAMS SYM_RPARENTHESIS INSTR { [Node(Tfunname, [$1]); Node(Tfunargs, $3); Node(Tfunbody, [$5])] }
 
 LPARAMS -> IDENTIFIER REST_PARAMS { $1::$2 }
 LPARAMS -> { [] }
@@ -46,10 +46,11 @@ INSTRS -> INSTR INSTRS { $1::$2 }
 INSTRS -> { [] }
 
 INSTR -> SYM_IF SYM_LPARENTHESIS EXPR SYM_RPARENTHESIS SYM_LBRACE LINSTRS SYM_RBRACE ELSE { Node(Tif, [$3; $6; $8]) }
-INSTR -> SYM_WHILE SYM_LPARENTHESIS EXPR SYM_RPARENTHESIS SYM_LBRACE LINSTRS SYM_RBRACE { Node(Twhile, [$3; $6]) }
+INSTR -> SYM_WHILE SYM_LPARENTHESIS EXPR SYM_RPARENTHESIS INSTR { Node(Twhile, [$3; $5]) }
 INSTR -> SYM_RETURN EXPR SYM_SEMICOLON { Node(Treturn, [$2]) }
 INSTR -> SYM_PRINT SYM_LPARENTHESIS EXPR SYM_RPARENTHESIS SYM_SEMICOLON { Node(Tprint, [$3]) }
 INSTR -> IDENTIFIER SYM_ASSIGN EXPR SYM_SEMICOLON { Node(Tassign, [$1; $3]) }
+INSTR -> SYM_LBRACE LINSTRS SYM_RBRACE { $2 }
 
 ELSE -> SYM_ELSE SYM_LBRACE LINSTRS SYM_RBRACE { $3 }
 ELSE -> { NullLeaf }