diff --git a/tests/cases/checker/02_simple_operations.py.ref.json b/tests/cases/checker/02_simple_operations.py.ref.json
index e3881e0..a2c5569 100644
--- a/tests/cases/checker/02_simple_operations.py.ref.json
+++ b/tests/cases/checker/02_simple_operations.py.ref.json
@@ -13,6 +13,20 @@
         ]
       },
       "message": "Cannot assign str to variable 'c' of type int"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          9,
+          4
+        ],
+        "end": [
+          9,
+          9
+        ]
+      },
+      "message": "Undefined operation __add__ between bool and bool"
     }
   ],
   "judgments": [
@@ -158,9 +172,7 @@
           "name": "d"
         }
       },
-      "type": {
-        "name": "int"
-      }
+      "type": {}
     },
     {
       "location": {
diff --git a/tests/cases/checker/03_functions.py.ref.json b/tests/cases/checker/03_functions.py.ref.json
index 3442bca..756a143 100644
--- a/tests/cases/checker/03_functions.py.ref.json
+++ b/tests/cases/checker/03_functions.py.ref.json
@@ -264,7 +264,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -328,7 +327,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -410,7 +408,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -509,7 +506,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -609,7 +605,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -725,7 +720,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -842,7 +836,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -924,7 +917,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -1006,7 +998,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -1123,7 +1114,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -1240,7 +1230,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
@@ -1357,7 +1346,6 @@
         "name": "foo"
       },
       "type": {
-        "name": "foo",
         "pos_args": [
           {
             "pos": 0,
diff --git a/tests/cases/checker/04_custom_types.midas b/tests/cases/checker/04_custom_types.midas
index 6a1a6a2..ff4edb1 100644
--- a/tests/cases/checker/04_custom_types.midas
+++ b/tests/cases/checker/04_custom_types.midas
@@ -3,12 +3,12 @@ type Second = float
 type MeterPerSecond = float
 
 extend Meter {
-    op __add__(Meter) -> Meter
-    op __sub__(Meter) -> Meter
-    op __truediv__(Second) -> MeterPerSecond
+    def __add__: fn(Meter, /) -> Meter
+    def __sub__: fn(Meter, /) -> Meter
+    def __truediv__: fn(Second, /) -> MeterPerSecond
 }
 
 extend Second {
-    op __add__(Second) -> Second
-    op __sub__(Second) -> Second
+    def __add__: fn(Second, /) -> Second
+    def __sub__: fn(Second, /) -> Second
 }
diff --git a/tests/cases/checker/06_subtyping.py b/tests/cases/checker/06_subtyping.py
index c334ab8..7ab9dd7 100644
--- a/tests/cases/checker/06_subtyping.py
+++ b/tests/cases/checker/06_subtyping.py
@@ -9,4 +9,4 @@ def maximum(a: float, b: float):
 
 
 v3 = maximum(v1, v2)
-v3 = v1 + v2
+v3 = v2 + v1
diff --git a/tests/cases/checker/06_subtyping.py.ref.json b/tests/cases/checker/06_subtyping.py.ref.json
index 689402e..0659939 100644
--- a/tests/cases/checker/06_subtyping.py.ref.json
+++ b/tests/cases/checker/06_subtyping.py.ref.json
@@ -63,7 +63,6 @@
         "name": "maximum"
       },
       "type": {
-        "name": "maximum",
         "pos_args": [],
         "args": [
           {
@@ -149,10 +148,10 @@
       },
       "expr": {
         "_type": "VariableExpr",
-        "name": "v1"
+        "name": "v2"
       },
       "type": {
-        "name": "int"
+        "name": "float"
       }
     },
     {
@@ -162,10 +161,10 @@
       },
       "expr": {
         "_type": "VariableExpr",
-        "name": "v2"
+        "name": "v1"
       },
       "type": {
-        "name": "float"
+        "name": "int"
       }
     },
     {
@@ -177,12 +176,12 @@
         "_type": "BinaryExpr",
         "left": {
           "_type": "VariableExpr",
-          "name": "v1"
+          "name": "v2"
         },
         "operator": "+",
         "right": {
           "_type": "VariableExpr",
-          "name": "v2"
+          "name": "v1"
         }
       },
       "type": {
diff --git a/tests/cases/midas-parser/01_simple_types.midas b/tests/cases/midas-parser/01_simple_types.midas
index 6446790..f0df3e2 100644
--- a/tests/cases/midas-parser/01_simple_types.midas
+++ b/tests/cases/midas-parser/01_simple_types.midas
@@ -10,8 +10,8 @@ type Difference[T] = T
 
 // Complex custom type, containing two values accessible through properties
 type GeoLocation = {
-    lat: Latitude
-    lon: Longitude
+    prop lat: Latitude
+    prop lon: Longitude
 }
 
 // Define operations on our custom type
@@ -19,23 +19,23 @@ extend GeoLocation {
     // This type is compatible with the `-` operation with another GeoLocation
     // i.e. you can subtract a GeoLocation from another GeoLocation, resulting
     // in a Difference of GeoLocations
-    op __sub__(GeoLocation) -> Difference[GeoLocation]
+    def __sub__: fn(GeoLocation, /) -> Difference[GeoLocation]
 }
 
 // For complex generics, you need to specify how the genericity the properties
 // are handled
 type Difference[GeoLocation] = {
-    lat: Difference[Latitude]
-    lon: Difference[Longitude]
+    prop lat: Difference[Latitude]
+    prop lon: Difference[Longitude]
 }
 
 // Simple operation defined on our custom types
 extend Latitude {
-    op __sub__(Latitude) -> Difference[Latitude]
+    def __sub__: fn(Latitude, /) -> Difference[Latitude]
 }
 
 extend Longitude {
-    op __sub__(Longitude) -> Difference[Longitude]
+    def __sub__: fn(Longitude, /) -> Difference[Longitude]
 }
 
 // Predefined custom predicates that can be referenced in other definitions
@@ -45,13 +45,13 @@ predicate Equatorial(loc: GeoLocation) = (-10 <= loc.lat <= 10)
 predicate Arctic(loc: GeoLocation) = (loc.lat >= 66)
 
 type Person = {
-    name: str
+    prop name: str
 
     // Property with an inline constraint
-    age: Optional[int where (0 <= _ < 150)]
+    prop age: Optional[int where (0 <= _ < 150)]
 
     // Property referencing a predicate
-    height: float where StrictlyPositive
+    prop height: float where StrictlyPositive
 
-    home: GeoLocation
+    prop home: GeoLocation
 }
diff --git a/tests/cases/midas-parser/01_simple_types.midas.ref.json b/tests/cases/midas-parser/01_simple_types.midas.ref.json
index 1d94718..be45687 100644
--- a/tests/cases/midas-parser/01_simple_types.midas.ref.json
+++ b/tests/cases/midas-parser/01_simple_types.midas.ref.json
@@ -511,17 +511,11 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "lat",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 13,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 13,
-      "column": 8
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -530,15 +524,33 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Latitude",
+      "lexeme": "lat",
       "line": 13,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 13,
+      "column": 13
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 13,
+      "column": 14
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "Latitude",
+      "line": 13,
+      "column": 15
+    },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 13,
-      "column": 18
+      "column": 23
     },
     {
       "type": "WHITESPACE",
@@ -547,17 +559,11 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "lon",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 14,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 14,
-      "column": 8
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -566,15 +572,33 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Longitude",
+      "lexeme": "lon",
       "line": 14,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 14,
+      "column": 13
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 14,
+      "column": 14
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "Longitude",
+      "line": 14,
+      "column": 15
+    },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 14,
-      "column": 19
+      "column": 24
     },
     {
       "type": "RIGHT_BRACE",
@@ -703,8 +727,8 @@
       "column": 1
     },
     {
-      "type": "OP",
-      "lexeme": "op",
+      "type": "DEF",
+      "lexeme": "def",
       "line": 22,
       "column": 5
     },
@@ -712,79 +736,115 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 22,
-      "column": 7
+      "column": 8
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "__sub__",
       "line": 22,
-      "column": 8
+      "column": 9
+    },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 22,
+      "column": 16
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 22,
+      "column": 17
+    },
+    {
+      "type": "FUNC",
+      "lexeme": "fn",
+      "line": 22,
+      "column": 18
     },
     {
       "type": "LEFT_PAREN",
       "lexeme": "(",
       "line": 22,
-      "column": 15
+      "column": 20
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "GeoLocation",
       "line": 22,
-      "column": 16
+      "column": 21
+    },
+    {
+      "type": "COMMA",
+      "lexeme": ",",
+      "line": 22,
+      "column": 32
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 22,
+      "column": 33
+    },
+    {
+      "type": "SLASH",
+      "lexeme": "/",
+      "line": 22,
+      "column": 34
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 22,
-      "column": 27
+      "column": 35
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 22,
-      "column": 28
+      "column": 36
     },
     {
       "type": "ARROW",
       "lexeme": "->",
       "line": 22,
-      "column": 29
+      "column": 37
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 22,
-      "column": 31
+      "column": 39
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Difference",
       "line": 22,
-      "column": 32
+      "column": 40
     },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 22,
-      "column": 42
+      "column": 50
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "GeoLocation",
       "line": 22,
-      "column": 43
+      "column": 51
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 22,
-      "column": 54
+      "column": 62
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 22,
-      "column": 55
+      "column": 63
     },
     {
       "type": "RIGHT_BRACE",
@@ -901,17 +961,11 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "lat",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 28,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 28,
-      "column": 8
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -920,33 +974,51 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Difference",
+      "lexeme": "lat",
       "line": 28,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 28,
+      "column": 13
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 28,
+      "column": 14
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "Difference",
+      "line": 28,
+      "column": 15
+    },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 28,
-      "column": 20
+      "column": 25
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Latitude",
       "line": 28,
-      "column": 21
+      "column": 26
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 28,
-      "column": 29
+      "column": 34
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 28,
-      "column": 30
+      "column": 35
     },
     {
       "type": "WHITESPACE",
@@ -955,17 +1027,11 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "lon",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 29,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 29,
-      "column": 8
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -974,33 +1040,51 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Difference",
+      "lexeme": "lon",
       "line": 29,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 29,
+      "column": 13
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 29,
+      "column": 14
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "Difference",
+      "line": 29,
+      "column": 15
+    },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 29,
-      "column": 20
+      "column": 25
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Longitude",
       "line": 29,
-      "column": 21
+      "column": 26
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 29,
-      "column": 30
+      "column": 35
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 29,
-      "column": 31
+      "column": 36
     },
     {
       "type": "RIGHT_BRACE",
@@ -1075,8 +1159,8 @@
       "column": 1
     },
     {
-      "type": "OP",
-      "lexeme": "op",
+      "type": "DEF",
+      "lexeme": "def",
       "line": 34,
       "column": 5
     },
@@ -1084,79 +1168,115 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 34,
-      "column": 7
+      "column": 8
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "__sub__",
       "line": 34,
-      "column": 8
+      "column": 9
+    },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 34,
+      "column": 16
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 34,
+      "column": 17
+    },
+    {
+      "type": "FUNC",
+      "lexeme": "fn",
+      "line": 34,
+      "column": 18
     },
     {
       "type": "LEFT_PAREN",
       "lexeme": "(",
       "line": 34,
-      "column": 15
+      "column": 20
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Latitude",
       "line": 34,
-      "column": 16
+      "column": 21
+    },
+    {
+      "type": "COMMA",
+      "lexeme": ",",
+      "line": 34,
+      "column": 29
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 34,
+      "column": 30
+    },
+    {
+      "type": "SLASH",
+      "lexeme": "/",
+      "line": 34,
+      "column": 31
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 34,
-      "column": 24
+      "column": 32
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 34,
-      "column": 25
+      "column": 33
     },
     {
       "type": "ARROW",
       "lexeme": "->",
       "line": 34,
-      "column": 26
+      "column": 34
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 34,
-      "column": 28
+      "column": 36
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Difference",
       "line": 34,
-      "column": 29
+      "column": 37
     },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 34,
-      "column": 39
+      "column": 47
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Latitude",
       "line": 34,
-      "column": 40
+      "column": 48
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 34,
-      "column": 48
+      "column": 56
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 34,
-      "column": 49
+      "column": 57
     },
     {
       "type": "RIGHT_BRACE",
@@ -1219,8 +1339,8 @@
       "column": 1
     },
     {
-      "type": "OP",
-      "lexeme": "op",
+      "type": "DEF",
+      "lexeme": "def",
       "line": 38,
       "column": 5
     },
@@ -1228,79 +1348,115 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 38,
-      "column": 7
+      "column": 8
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "__sub__",
       "line": 38,
-      "column": 8
+      "column": 9
+    },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 38,
+      "column": 16
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 38,
+      "column": 17
+    },
+    {
+      "type": "FUNC",
+      "lexeme": "fn",
+      "line": 38,
+      "column": 18
     },
     {
       "type": "LEFT_PAREN",
       "lexeme": "(",
       "line": 38,
-      "column": 15
+      "column": 20
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Longitude",
       "line": 38,
-      "column": 16
+      "column": 21
+    },
+    {
+      "type": "COMMA",
+      "lexeme": ",",
+      "line": 38,
+      "column": 30
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 38,
+      "column": 31
+    },
+    {
+      "type": "SLASH",
+      "lexeme": "/",
+      "line": 38,
+      "column": 32
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 38,
-      "column": 25
+      "column": 33
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 38,
-      "column": 26
+      "column": 34
     },
     {
       "type": "ARROW",
       "lexeme": "->",
       "line": 38,
-      "column": 27
+      "column": 35
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 38,
-      "column": 29
+      "column": 37
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Difference",
       "line": 38,
-      "column": 30
+      "column": 38
     },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 38,
-      "column": 40
+      "column": 48
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "Longitude",
       "line": 38,
-      "column": 41
+      "column": 49
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 38,
-      "column": 50
+      "column": 58
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 38,
-      "column": 51
+      "column": 59
     },
     {
       "type": "RIGHT_BRACE",
@@ -1903,34 +2059,46 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "name",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 48,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 48,
-      "column": 9
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 48,
+      "column": 9
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "name",
+      "line": 48,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 48,
+      "column": 14
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 48,
+      "column": 15
+    },
     {
       "type": "IDENTIFIER",
       "lexeme": "str",
       "line": 48,
-      "column": 11
+      "column": 16
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 48,
-      "column": 14
+      "column": 19
     },
     {
       "type": "NEWLINE",
@@ -1963,17 +2131,11 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "age",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 51,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 51,
-      "column": 8
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -1982,74 +2144,68 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Optional",
+      "lexeme": "age",
       "line": 51,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 51,
+      "column": 13
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 51,
+      "column": 14
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "Optional",
+      "line": 51,
+      "column": 15
+    },
     {
       "type": "LEFT_BRACKET",
       "lexeme": "[",
       "line": 51,
-      "column": 18
+      "column": 23
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "int",
       "line": 51,
-      "column": 19
+      "column": 24
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 51,
-      "column": 22
+      "column": 27
     },
     {
       "type": "WHERE",
       "lexeme": "where",
       "line": 51,
-      "column": 23
+      "column": 28
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 51,
-      "column": 28
+      "column": 33
     },
     {
       "type": "LEFT_PAREN",
       "lexeme": "(",
       "line": 51,
-      "column": 29
+      "column": 34
     },
     {
       "type": "NUMBER",
       "lexeme": "0",
       "line": 51,
-      "column": 30
-    },
-    {
-      "type": "WHITESPACE",
-      "lexeme": " ",
-      "line": 51,
-      "column": 31
-    },
-    {
-      "type": "LESS_EQUAL",
-      "lexeme": "<=",
-      "line": 51,
-      "column": 32
-    },
-    {
-      "type": "WHITESPACE",
-      "lexeme": " ",
-      "line": 51,
-      "column": 34
-    },
-    {
-      "type": "UNDERSCORE",
-      "lexeme": "_",
-      "line": 51,
       "column": 35
     },
     {
@@ -2059,8 +2215,8 @@
       "column": 36
     },
     {
-      "type": "LESS",
-      "lexeme": "<",
+      "type": "LESS_EQUAL",
+      "lexeme": "<=",
       "line": 51,
       "column": 37
     },
@@ -2068,31 +2224,55 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 51,
-      "column": 38
+      "column": 39
+    },
+    {
+      "type": "UNDERSCORE",
+      "lexeme": "_",
+      "line": 51,
+      "column": 40
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 51,
+      "column": 41
+    },
+    {
+      "type": "LESS",
+      "lexeme": "<",
+      "line": 51,
+      "column": 42
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 51,
+      "column": 43
     },
     {
       "type": "NUMBER",
       "lexeme": "150",
       "line": 51,
-      "column": 39
+      "column": 44
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 51,
-      "column": 42
+      "column": 47
     },
     {
       "type": "RIGHT_BRACKET",
       "lexeme": "]",
       "line": 51,
-      "column": 43
+      "column": 48
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 51,
-      "column": 44
+      "column": 49
     },
     {
       "type": "NEWLINE",
@@ -2124,59 +2304,71 @@
       "line": 54,
       "column": 1
     },
+    {
+      "type": "PROP",
+      "lexeme": "prop",
+      "line": 54,
+      "column": 5
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 54,
+      "column": 9
+    },
     {
       "type": "IDENTIFIER",
       "lexeme": "height",
       "line": 54,
-      "column": 5
+      "column": 10
     },
     {
       "type": "COLON",
       "lexeme": ":",
       "line": 54,
-      "column": 11
+      "column": 16
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 54,
-      "column": 12
+      "column": 17
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "float",
       "line": 54,
-      "column": 13
+      "column": 18
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 54,
-      "column": 18
+      "column": 23
     },
     {
       "type": "WHERE",
       "lexeme": "where",
       "line": 54,
-      "column": 19
+      "column": 24
     },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 54,
-      "column": 24
+      "column": 29
     },
     {
       "type": "IDENTIFIER",
       "lexeme": "StrictlyPositive",
       "line": 54,
-      "column": 25
+      "column": 30
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 54,
-      "column": 41
+      "column": 46
     },
     {
       "type": "NEWLINE",
@@ -2191,34 +2383,46 @@
       "column": 1
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "home",
+      "type": "PROP",
+      "lexeme": "prop",
       "line": 56,
       "column": 5
     },
-    {
-      "type": "COLON",
-      "lexeme": ":",
-      "line": 56,
-      "column": 9
-    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 56,
+      "column": 9
+    },
+    {
+      "type": "IDENTIFIER",
+      "lexeme": "home",
+      "line": 56,
       "column": 10
     },
+    {
+      "type": "COLON",
+      "lexeme": ":",
+      "line": 56,
+      "column": 14
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 56,
+      "column": 15
+    },
     {
       "type": "IDENTIFIER",
       "lexeme": "GeoLocation",
       "line": 56,
-      "column": 11
+      "column": 16
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 56,
-      "column": 22
+      "column": 27
     },
     {
       "type": "RIGHT_BRACE",
@@ -2345,9 +2549,10 @@
       "params": [],
       "type": {
         "_type": "ComplexType",
-        "properties": [
+        "members": [
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "lat",
             "type": {
               "_type": "NamedType",
@@ -2355,7 +2560,8 @@
             }
           },
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "lon",
             "type": {
               "_type": "NamedType",
@@ -2367,30 +2573,40 @@
     },
     {
       "_type": "ExtendStmt",
-      "type": {
-        "_type": "NamedType",
-        "name": "GeoLocation"
-      },
-      "operations": [
+      "name": "GeoLocation",
+      "params": [],
+      "members": [
         {
-          "_type": "OpStmt",
+          "_type": "MemberStmt",
+          "kind": "METHOD",
           "name": "__sub__",
-          "operand": {
-            "_type": "NamedType",
-            "name": "GeoLocation"
-          },
-          "result": {
-            "_type": "GenericType",
-            "type": {
-              "_type": "NamedType",
-              "name": "Difference"
-            },
-            "args": [
+          "type": {
+            "_type": "FunctionType",
+            "pos_args": [
               {
-                "_type": "NamedType",
-                "name": "GeoLocation"
+                "name": null,
+                "type": {
+                  "_type": "NamedType",
+                  "name": "GeoLocation"
+                },
+                "required": true
               }
-            ]
+            ],
+            "args": [],
+            "kw_args": [],
+            "returns": {
+              "_type": "GenericType",
+              "type": {
+                "_type": "NamedType",
+                "name": "Difference"
+              },
+              "args": [
+                {
+                  "_type": "NamedType",
+                  "name": "GeoLocation"
+                }
+              ]
+            }
           }
         }
       ]
@@ -2406,9 +2622,10 @@
       ],
       "type": {
         "_type": "ComplexType",
-        "properties": [
+        "members": [
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "lat",
             "type": {
               "_type": "GenericType",
@@ -2425,7 +2642,8 @@
             }
           },
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "lon",
             "type": {
               "_type": "GenericType",
@@ -2446,60 +2664,80 @@
     },
     {
       "_type": "ExtendStmt",
-      "type": {
-        "_type": "NamedType",
-        "name": "Latitude"
-      },
-      "operations": [
+      "name": "Latitude",
+      "params": [],
+      "members": [
         {
-          "_type": "OpStmt",
+          "_type": "MemberStmt",
+          "kind": "METHOD",
           "name": "__sub__",
-          "operand": {
-            "_type": "NamedType",
-            "name": "Latitude"
-          },
-          "result": {
-            "_type": "GenericType",
-            "type": {
-              "_type": "NamedType",
-              "name": "Difference"
-            },
-            "args": [
+          "type": {
+            "_type": "FunctionType",
+            "pos_args": [
               {
-                "_type": "NamedType",
-                "name": "Latitude"
+                "name": null,
+                "type": {
+                  "_type": "NamedType",
+                  "name": "Latitude"
+                },
+                "required": true
               }
-            ]
+            ],
+            "args": [],
+            "kw_args": [],
+            "returns": {
+              "_type": "GenericType",
+              "type": {
+                "_type": "NamedType",
+                "name": "Difference"
+              },
+              "args": [
+                {
+                  "_type": "NamedType",
+                  "name": "Latitude"
+                }
+              ]
+            }
           }
         }
       ]
     },
     {
       "_type": "ExtendStmt",
-      "type": {
-        "_type": "NamedType",
-        "name": "Longitude"
-      },
-      "operations": [
+      "name": "Longitude",
+      "params": [],
+      "members": [
         {
-          "_type": "OpStmt",
+          "_type": "MemberStmt",
+          "kind": "METHOD",
           "name": "__sub__",
-          "operand": {
-            "_type": "NamedType",
-            "name": "Longitude"
-          },
-          "result": {
-            "_type": "GenericType",
-            "type": {
-              "_type": "NamedType",
-              "name": "Difference"
-            },
-            "args": [
+          "type": {
+            "_type": "FunctionType",
+            "pos_args": [
               {
-                "_type": "NamedType",
-                "name": "Longitude"
+                "name": null,
+                "type": {
+                  "_type": "NamedType",
+                  "name": "Longitude"
+                },
+                "required": true
               }
-            ]
+            ],
+            "args": [],
+            "kw_args": [],
+            "returns": {
+              "_type": "GenericType",
+              "type": {
+                "_type": "NamedType",
+                "name": "Difference"
+              },
+              "args": [
+                {
+                  "_type": "NamedType",
+                  "name": "Longitude"
+                }
+              ]
+            }
           }
         }
       ]
@@ -2620,9 +2858,10 @@
       "params": [],
       "type": {
         "_type": "ComplexType",
-        "properties": [
+        "members": [
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "name",
             "type": {
               "_type": "NamedType",
@@ -2630,7 +2869,8 @@
             }
           },
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "age",
             "type": {
               "_type": "GenericType",
@@ -2672,7 +2912,8 @@
             }
           },
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "height",
             "type": {
               "_type": "ConstraintType",
@@ -2687,7 +2928,8 @@
             }
           },
           {
-            "_type": "PropertyStmt",
+            "_type": "MemberStmt",
+            "kind": "PROPERTY",
             "name": "home",
             "type": {
               "_type": "NamedType",