diff --git a/corpus/tests.txt b/corpus/tests.txt
index 0c39d2c..95f15e7 100644
--- a/corpus/tests.txt
+++ b/corpus/tests.txt
@@ -14,3 +14,63 @@ x # xyz
 	(expression
 		(identifier))
 	(comment))
+
+==================
+Identifiers
+==================
+
+variable_name
+_unused_variable
+__strange_format__
+a
+blahblah
+x.x
+
+---
+
+(source_file
+	(expression
+		(identifier))
+	(expression
+		(identifier))
+	(expression
+		(identifier))
+	(expression
+		(identifier))
+	(expression
+		(identifier))
+	(expression
+		(identifier)))
+
+==================
+Operators
+==================
+
++ - = / & |
+
+---
+
+(source_file
+	(expression
+		(operator)
+		(operator)
+		(operator)
+		(operator)
+		(operator)
+		(operator)))
+
+==================
+Expressions
+==================
+
+x_x = 1;
+
+---
+
+(source_file
+	(expression
+		(identifier))
+		(operator)
+		(integer)))
+
+
diff --git a/grammar.js b/grammar.js
index 166a92e..f192083 100644
--- a/grammar.js
+++ b/grammar.js
@@ -4,18 +4,24 @@ module.exports = grammar({
   rules: {
     source_file: $ => repeat(choice($.comment, $.expression)),
 
+    identifier: $ => /[a-zA-Z|_|.]+(_[a-zA-Z]+)*/,
+
     comment: $ => /(#)(.+?)([\n\r])/,
 
     expression: $ => choice(
-      $.identifier
-      // TODO: other kinds of definitions
+      $.identifier,
+      seq($.identifier, $.operator, $.identifier)
+      
     ),
 
-    identifier: $ => /[a-zA-Z]+(_[a-zA-Z]+)*/,
-
     operator: $ => choice(
       '=',
-      "+",
+      '-',
+      '+',
+      ';',
+      '/',
+      '|',
+      '&'
     ),
 
     integer: $ => /\d/,
diff --git a/src/grammar.json b/src/grammar.json
index 7a40701..ab727d7 100644
--- a/src/grammar.json
+++ b/src/grammar.json
@@ -17,6 +17,10 @@
         ]
       }
     },
+    "identifier": {
+      "type": "PATTERN",
+      "value": "[a-zA-Z|_|.]+(_[a-zA-Z]+)*"
+    },
     "comment": {
       "type": "PATTERN",
       "value": "(#)(.+?)([\\n\\r])"
@@ -27,13 +31,26 @@
         {
           "type": "SYMBOL",
           "name": "identifier"
+        },
+        {
+          "type": "SEQ",
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "identifier"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "operator"
+            },
+            {
+              "type": "SYMBOL",
+              "name": "identifier"
+            }
+          ]
         }
       ]
     },
-    "identifier": {
-      "type": "PATTERN",
-      "value": "[a-zA-Z]+(_[a-zA-Z]+)*"
-    },
     "operator": {
       "type": "CHOICE",
       "members": [
@@ -41,9 +58,29 @@
           "type": "STRING",
           "value": "="
         },
+        {
+          "type": "STRING",
+          "value": "-"
+        },
         {
           "type": "STRING",
           "value": "+"
+        },
+        {
+          "type": "STRING",
+          "value": ";"
+        },
+        {
+          "type": "STRING",
+          "value": "/"
+        },
+        {
+          "type": "STRING",
+          "value": "|"
+        },
+        {
+          "type": "STRING",
+          "value": "&"
         }
       ]
     },
diff --git a/src/node-types.json b/src/node-types.json
index 2201003..720ec73 100644
--- a/src/node-types.json
+++ b/src/node-types.json
@@ -4,16 +4,25 @@
     "named": true,
     "fields": {},
     "children": {
-      "multiple": false,
+      "multiple": true,
       "required": true,
       "types": [
         {
           "type": "identifier",
           "named": true
+        },
+        {
+          "type": "operator",
+          "named": true
         }
       ]
     }
   },
+  {
+    "type": "operator",
+    "named": true,
+    "fields": {}
+  },
   {
     "type": "source_file",
     "named": true,
@@ -33,10 +42,26 @@
       ]
     }
   },
+  {
+    "type": "&",
+    "named": false
+  },
   {
     "type": "+",
     "named": false
   },
+  {
+    "type": "-",
+    "named": false
+  },
+  {
+    "type": "/",
+    "named": false
+  },
+  {
+    "type": ";",
+    "named": false
+  },
   {
     "type": "=",
     "named": false
@@ -48,5 +73,9 @@
   {
     "type": "identifier",
     "named": true
+  },
+  {
+    "type": "|",
+    "named": false
   }
 ]
\ No newline at end of file
diff --git a/src/parser.c b/src/parser.c
index 678081b..c6891a6 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -6,48 +6,66 @@
 #endif
 
 #define LANGUAGE_VERSION 14
-#define STATE_COUNT 6
-#define LARGE_STATE_COUNT 4
-#define SYMBOL_COUNT 9
+#define STATE_COUNT 9
+#define LARGE_STATE_COUNT 3
+#define SYMBOL_COUNT 15
 #define ALIAS_COUNT 0
-#define TOKEN_COUNT 6
+#define TOKEN_COUNT 11
 #define EXTERNAL_TOKEN_COUNT 0
 #define FIELD_COUNT 0
-#define MAX_ALIAS_SEQUENCE_LENGTH 2
+#define MAX_ALIAS_SEQUENCE_LENGTH 3
 #define PRODUCTION_ID_COUNT 1
 
 enum {
-  sym_comment = 1,
-  sym_identifier = 2,
+  sym_identifier = 1,
+  sym_comment = 2,
   anon_sym_EQ = 3,
-  anon_sym_PLUS = 4,
-  sym_integer = 5,
-  sym_source_file = 6,
-  sym_expression = 7,
-  aux_sym_source_file_repeat1 = 8,
+  anon_sym_DASH = 4,
+  anon_sym_PLUS = 5,
+  anon_sym_SEMI = 6,
+  anon_sym_SLASH = 7,
+  anon_sym_PIPE = 8,
+  anon_sym_AMP = 9,
+  sym_integer = 10,
+  sym_source_file = 11,
+  sym_expression = 12,
+  sym_operator = 13,
+  aux_sym_source_file_repeat1 = 14,
 };
 
 static const char * const ts_symbol_names[] = {
   [ts_builtin_sym_end] = "end",
-  [sym_comment] = "comment",
   [sym_identifier] = "identifier",
+  [sym_comment] = "comment",
   [anon_sym_EQ] = "=",
+  [anon_sym_DASH] = "-",
   [anon_sym_PLUS] = "+",
+  [anon_sym_SEMI] = ";",
+  [anon_sym_SLASH] = "/",
+  [anon_sym_PIPE] = "|",
+  [anon_sym_AMP] = "&",
   [sym_integer] = "integer",
   [sym_source_file] = "source_file",
   [sym_expression] = "expression",
+  [sym_operator] = "operator",
   [aux_sym_source_file_repeat1] = "source_file_repeat1",
 };
 
 static const TSSymbol ts_symbol_map[] = {
   [ts_builtin_sym_end] = ts_builtin_sym_end,
-  [sym_comment] = sym_comment,
   [sym_identifier] = sym_identifier,
+  [sym_comment] = sym_comment,
   [anon_sym_EQ] = anon_sym_EQ,
+  [anon_sym_DASH] = anon_sym_DASH,
   [anon_sym_PLUS] = anon_sym_PLUS,
+  [anon_sym_SEMI] = anon_sym_SEMI,
+  [anon_sym_SLASH] = anon_sym_SLASH,
+  [anon_sym_PIPE] = anon_sym_PIPE,
+  [anon_sym_AMP] = anon_sym_AMP,
   [sym_integer] = sym_integer,
   [sym_source_file] = sym_source_file,
   [sym_expression] = sym_expression,
+  [sym_operator] = sym_operator,
   [aux_sym_source_file_repeat1] = aux_sym_source_file_repeat1,
 };
 
@@ -56,11 +74,11 @@ static const TSSymbolMetadata ts_symbol_metadata[] = {
     .visible = false,
     .named = true,
   },
-  [sym_comment] = {
+  [sym_identifier] = {
     .visible = true,
     .named = true,
   },
-  [sym_identifier] = {
+  [sym_comment] = {
     .visible = true,
     .named = true,
   },
@@ -68,10 +86,30 @@ static const TSSymbolMetadata ts_symbol_metadata[] = {
     .visible = true,
     .named = false,
   },
+  [anon_sym_DASH] = {
+    .visible = true,
+    .named = false,
+  },
   [anon_sym_PLUS] = {
     .visible = true,
     .named = false,
   },
+  [anon_sym_SEMI] = {
+    .visible = true,
+    .named = false,
+  },
+  [anon_sym_SLASH] = {
+    .visible = true,
+    .named = false,
+  },
+  [anon_sym_PIPE] = {
+    .visible = true,
+    .named = false,
+  },
+  [anon_sym_AMP] = {
+    .visible = true,
+    .named = false,
+  },
   [sym_integer] = {
     .visible = true,
     .named = true,
@@ -84,6 +122,10 @@ static const TSSymbolMetadata ts_symbol_metadata[] = {
     .visible = true,
     .named = true,
   },
+  [sym_operator] = {
+    .visible = true,
+    .named = true,
+  },
   [aux_sym_source_file_repeat1] = {
     .visible = false,
     .named = false,
@@ -105,6 +147,9 @@ static const TSStateId ts_primary_state_ids[STATE_COUNT] = {
   [3] = 3,
   [4] = 4,
   [5] = 5,
+  [6] = 6,
+  [7] = 7,
+  [8] = 8,
 };
 
 static bool ts_lex(TSLexer *lexer, TSStateId state) {
@@ -113,55 +158,101 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
   switch (state) {
     case 0:
       if (eof) ADVANCE(4);
-      if (lookahead == '#') ADVANCE(3);
-      if (lookahead == '+') ADVANCE(9);
-      if (lookahead == '=') ADVANCE(8);
+      if (lookahead == '#') ADVANCE(2);
+      if (lookahead == '&') ADVANCE(15);
+      if (lookahead == '+') ADVANCE(11);
+      if (lookahead == '-') ADVANCE(10);
+      if (lookahead == '/') ADVANCE(13);
+      if (lookahead == ';') ADVANCE(12);
+      if (lookahead == '=') ADVANCE(9);
+      if (lookahead == '|') ADVANCE(14);
       if (lookahead == '\t' ||
           lookahead == '\n' ||
           lookahead == '\r' ||
           lookahead == ' ') SKIP(0)
-      if (('0' <= lookahead && lookahead <= '9')) ADVANCE(10);
-      if (('A' <= lookahead && lookahead <= 'Z') ||
-          ('a' <= lookahead && lookahead <= 'z')) ADVANCE(7);
+      if (('0' <= lookahead && lookahead <= '9')) ADVANCE(16);
+      if (lookahead == '.' ||
+          ('A' <= lookahead && lookahead <= 'Z') ||
+          lookahead == '_' ||
+          ('a' <= lookahead && lookahead <= 'z')) ADVANCE(6);
       END_STATE();
     case 1:
-      if (lookahead == '\n') ADVANCE(5);
-      if (lookahead == '\r') ADVANCE(6);
+      if (lookahead == '\n') ADVANCE(7);
+      if (lookahead == '\r') ADVANCE(8);
       if (lookahead != 0) ADVANCE(1);
       END_STATE();
     case 2:
-      if (('A' <= lookahead && lookahead <= 'Z') ||
-          ('a' <= lookahead && lookahead <= 'z')) ADVANCE(7);
-      END_STATE();
-    case 3:
       if (lookahead != 0 &&
           lookahead != '\n') ADVANCE(1);
       END_STATE();
+    case 3:
+      if (eof) ADVANCE(4);
+      if (lookahead == '#') ADVANCE(2);
+      if (lookahead == '\t' ||
+          lookahead == '\n' ||
+          lookahead == '\r' ||
+          lookahead == ' ') SKIP(3)
+      if (lookahead == '.' ||
+          ('A' <= lookahead && lookahead <= 'Z') ||
+          lookahead == '_' ||
+          ('a' <= lookahead && lookahead <= 'z') ||
+          lookahead == '|') ADVANCE(6);
+      END_STATE();
     case 4:
       ACCEPT_TOKEN(ts_builtin_sym_end);
       END_STATE();
     case 5:
-      ACCEPT_TOKEN(sym_comment);
+      ACCEPT_TOKEN(sym_identifier);
+      if (lookahead == '_') ADVANCE(5);
+      if (lookahead == '.' ||
+          lookahead == '|') ADVANCE(6);
+      if (('A' <= lookahead && lookahead <= 'Z') ||
+          ('a' <= lookahead && lookahead <= 'z')) ADVANCE(5);
       END_STATE();
     case 6:
-      ACCEPT_TOKEN(sym_comment);
-      if (lookahead == '\n') ADVANCE(5);
-      if (lookahead == '\r') ADVANCE(6);
-      if (lookahead != 0) ADVANCE(1);
+      ACCEPT_TOKEN(sym_identifier);
+      if (lookahead == '_') ADVANCE(5);
+      if (lookahead == '.' ||
+          ('A' <= lookahead && lookahead <= 'Z') ||
+          ('a' <= lookahead && lookahead <= 'z') ||
+          lookahead == '|') ADVANCE(6);
       END_STATE();
     case 7:
-      ACCEPT_TOKEN(sym_identifier);
-      if (lookahead == '_') ADVANCE(2);
-      if (('A' <= lookahead && lookahead <= 'Z') ||
-          ('a' <= lookahead && lookahead <= 'z')) ADVANCE(7);
+      ACCEPT_TOKEN(sym_comment);
       END_STATE();
     case 8:
-      ACCEPT_TOKEN(anon_sym_EQ);
+      ACCEPT_TOKEN(sym_comment);
+      if (lookahead == '\n') ADVANCE(7);
+      if (lookahead == '\r') ADVANCE(8);
+      if (lookahead != 0) ADVANCE(1);
       END_STATE();
     case 9:
-      ACCEPT_TOKEN(anon_sym_PLUS);
+      ACCEPT_TOKEN(anon_sym_EQ);
       END_STATE();
     case 10:
+      ACCEPT_TOKEN(anon_sym_DASH);
+      END_STATE();
+    case 11:
+      ACCEPT_TOKEN(anon_sym_PLUS);
+      END_STATE();
+    case 12:
+      ACCEPT_TOKEN(anon_sym_SEMI);
+      END_STATE();
+    case 13:
+      ACCEPT_TOKEN(anon_sym_SLASH);
+      END_STATE();
+    case 14:
+      ACCEPT_TOKEN(anon_sym_PIPE);
+      if (lookahead == '_') ADVANCE(5);
+      if (lookahead == '.' ||
+          ('A' <= lookahead && lookahead <= 'Z') ||
+          ('a' <= lookahead && lookahead <= 'z') ||
+          lookahead == '|') ADVANCE(6);
+      END_STATE();
+    case 15:
+      ACCEPT_TOKEN(anon_sym_AMP);
+      END_STATE();
+    case 16:
       ACCEPT_TOKEN(sym_integer);
       END_STATE();
     default:
@@ -171,60 +262,97 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
 
 static const TSLexMode ts_lex_modes[STATE_COUNT] = {
   [0] = {.lex_state = 0},
-  [1] = {.lex_state = 0},
+  [1] = {.lex_state = 3},
   [2] = {.lex_state = 0},
-  [3] = {.lex_state = 0},
-  [4] = {.lex_state = 0},
-  [5] = {.lex_state = 0},
+  [3] = {.lex_state = 3},
+  [4] = {.lex_state = 3},
+  [5] = {.lex_state = 3},
+  [6] = {.lex_state = 0},
+  [7] = {.lex_state = 3},
+  [8] = {.lex_state = 3},
 };
 
 static const uint16_t ts_parse_table[LARGE_STATE_COUNT][SYMBOL_COUNT] = {
   [0] = {
     [ts_builtin_sym_end] = ACTIONS(1),
-    [sym_comment] = ACTIONS(1),
     [sym_identifier] = ACTIONS(1),
+    [sym_comment] = ACTIONS(1),
     [anon_sym_EQ] = ACTIONS(1),
+    [anon_sym_DASH] = ACTIONS(1),
     [anon_sym_PLUS] = ACTIONS(1),
+    [anon_sym_SEMI] = ACTIONS(1),
+    [anon_sym_SLASH] = ACTIONS(1),
+    [anon_sym_PIPE] = ACTIONS(1),
+    [anon_sym_AMP] = ACTIONS(1),
     [sym_integer] = ACTIONS(1),
   },
   [1] = {
-    [sym_source_file] = STATE(5),
-    [sym_expression] = STATE(2),
-    [aux_sym_source_file_repeat1] = STATE(2),
+    [sym_source_file] = STATE(6),
+    [sym_expression] = STATE(3),
+    [aux_sym_source_file_repeat1] = STATE(3),
     [ts_builtin_sym_end] = ACTIONS(3),
-    [sym_comment] = ACTIONS(5),
-    [sym_identifier] = ACTIONS(7),
+    [sym_identifier] = ACTIONS(5),
+    [sym_comment] = ACTIONS(7),
   },
   [2] = {
-    [sym_expression] = STATE(3),
-    [aux_sym_source_file_repeat1] = STATE(3),
+    [sym_operator] = STATE(8),
     [ts_builtin_sym_end] = ACTIONS(9),
-    [sym_comment] = ACTIONS(11),
-    [sym_identifier] = ACTIONS(7),
-  },
-  [3] = {
-    [sym_expression] = STATE(3),
-    [aux_sym_source_file_repeat1] = STATE(3),
-    [ts_builtin_sym_end] = ACTIONS(13),
-    [sym_comment] = ACTIONS(15),
-    [sym_identifier] = ACTIONS(18),
+    [sym_identifier] = ACTIONS(11),
+    [sym_comment] = ACTIONS(9),
+    [anon_sym_EQ] = ACTIONS(13),
+    [anon_sym_DASH] = ACTIONS(13),
+    [anon_sym_PLUS] = ACTIONS(13),
+    [anon_sym_SEMI] = ACTIONS(13),
+    [anon_sym_SLASH] = ACTIONS(13),
+    [anon_sym_PIPE] = ACTIONS(15),
+    [anon_sym_AMP] = ACTIONS(13),
   },
 };
 
 static const uint16_t ts_small_parse_table[] = {
-  [0] = 1,
-    ACTIONS(21), 3,
-      ts_builtin_sym_end,
-      sym_comment,
+  [0] = 4,
+    ACTIONS(5), 1,
       sym_identifier,
-  [6] = 1,
-    ACTIONS(23), 1,
+    ACTIONS(17), 1,
       ts_builtin_sym_end,
+    ACTIONS(19), 1,
+      sym_comment,
+    STATE(4), 2,
+      sym_expression,
+      aux_sym_source_file_repeat1,
+  [14] = 4,
+    ACTIONS(21), 1,
+      ts_builtin_sym_end,
+    ACTIONS(23), 1,
+      sym_identifier,
+    ACTIONS(26), 1,
+      sym_comment,
+    STATE(4), 2,
+      sym_expression,
+      aux_sym_source_file_repeat1,
+  [28] = 1,
+    ACTIONS(29), 3,
+      ts_builtin_sym_end,
+      sym_identifier,
+      sym_comment,
+  [34] = 1,
+    ACTIONS(31), 1,
+      ts_builtin_sym_end,
+  [38] = 1,
+    ACTIONS(33), 1,
+      sym_identifier,
+  [42] = 1,
+    ACTIONS(35), 1,
+      sym_identifier,
 };
 
 static const uint32_t ts_small_parse_table_map[] = {
-  [SMALL_STATE(4)] = 0,
-  [SMALL_STATE(5)] = 6,
+  [SMALL_STATE(3)] = 0,
+  [SMALL_STATE(4)] = 14,
+  [SMALL_STATE(5)] = 28,
+  [SMALL_STATE(6)] = 34,
+  [SMALL_STATE(7)] = 38,
+  [SMALL_STATE(8)] = 42,
 };
 
 static const TSParseActionEntry ts_parse_actions[] = {
@@ -232,14 +360,20 @@ static const TSParseActionEntry ts_parse_actions[] = {
   [1] = {.entry = {.count = 1, .reusable = false}}, RECOVER(),
   [3] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_source_file, 0),
   [5] = {.entry = {.count = 1, .reusable = true}}, SHIFT(2),
-  [7] = {.entry = {.count = 1, .reusable = true}}, SHIFT(4),
-  [9] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_source_file, 1),
-  [11] = {.entry = {.count = 1, .reusable = true}}, SHIFT(3),
-  [13] = {.entry = {.count = 1, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2),
-  [15] = {.entry = {.count = 2, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2), SHIFT_REPEAT(3),
-  [18] = {.entry = {.count = 2, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2), SHIFT_REPEAT(4),
-  [21] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_expression, 1),
-  [23] = {.entry = {.count = 1, .reusable = true}},  ACCEPT_INPUT(),
+  [7] = {.entry = {.count = 1, .reusable = true}}, SHIFT(3),
+  [9] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_expression, 1),
+  [11] = {.entry = {.count = 1, .reusable = false}}, REDUCE(sym_expression, 1),
+  [13] = {.entry = {.count = 1, .reusable = true}}, SHIFT(7),
+  [15] = {.entry = {.count = 1, .reusable = false}}, SHIFT(7),
+  [17] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_source_file, 1),
+  [19] = {.entry = {.count = 1, .reusable = true}}, SHIFT(4),
+  [21] = {.entry = {.count = 1, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2),
+  [23] = {.entry = {.count = 2, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2), SHIFT_REPEAT(2),
+  [26] = {.entry = {.count = 2, .reusable = true}}, REDUCE(aux_sym_source_file_repeat1, 2), SHIFT_REPEAT(4),
+  [29] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_expression, 3),
+  [31] = {.entry = {.count = 1, .reusable = true}},  ACCEPT_INPUT(),
+  [33] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_operator, 1),
+  [35] = {.entry = {.count = 1, .reusable = true}}, SHIFT(5),
 };
 
 #ifdef __cplusplus