Merge pull request 'Avoid raising exceptions, report diagnostics instead' (#42) from fix/remove-raises into main

Reviewed-on: #42

LICENSE

@@ -0,0 +1,202 @@
+
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+   END OF TERMS AND CONDITIONS
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+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
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+   Copyright 2026 Louis Heredero
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README.md

@@ -1,5 +1,11 @@
 <h1>Midas</h1>
 
+<p align="center">
+<img src="assets/icon.svg" width="64">
+</p>
+
+<img src="https://git.kb28.ch/HEL/midas/actions/workflows/tests.yaml/badge.svg">
+
 *Midas* is a type system to _Maintain Integrity of Data with Annotated Structures_. In Greek mythology, [Midas](https://en.wikipedia.org/wiki/Midas) was a Phrygian king who was blessed with the gift of turning everything he touched into gold.
 
 *Midas* aims at providing Python developers with a simple annotation system to enable compile-time integrity and data type checks, as well as generating runtime assertions.
@@ -22,6 +28,8 @@ This framework is being developed as part of a Bachelor's Thesis by Louis Herede
   - [Showing Type Judgements](#showing-type-judgements)
   - [Validating Definitions](#validating-definitions)
 - [Tests](#tests)
+- [Contributing](#contributing)
+- [License](#license)
 </details>
 
 
@@ -161,3 +169,16 @@ Not specifying any subcommand is equivalent to running `run -a`
 - Run specific tests: `run tests/cases/test1.py tests/cases/test2.py ...`
 - Update all tests: `update -a`
 - Update specific tests: `update tests/cases/test1.py tests/cases/test2.py ...`
+
+## Contributing
+
+Feel free to [open an issue](https://git.kb28.ch/HEL/midas/issues) to report a bug or if you experience any issues with Midas.
+
+Contributions are also welcome so feel free to [open a pull request](https://git.kb28.ch/HEL/midas/pulls).
+
+> [!NOTE]
+> As this is part of my bachelor project, I will not accept any contributions before my defense
+
+## License
+
+Midas is distributed under the terms of the Apache-2.0 license. See [LICENSE](LICENSE) for details.

docs/architecture.typ

@@ -1,150 +0,0 @@
-#import "@preview/cetz:0.5.2": canvas, draw
-
-#let diagram-only = false
-
-#set document(
-  title: [Midas Architecture],
-  //author: "Louis Heredero",
-)
-
-#set text(
-  font: "Source Sans 3",
-)
-
-#let diagram = canvas({
-  let framed = draw.content.with(
-    padding: (x: .8em, y: 1em),
-    frame: "rect",
-    stroke: black,
-  )
-  let arrow = draw.line.with(mark: (end: ">", fill: black))
-  framed(
-    (0, 0),
-    name: "python-parser",
-  )[Python parser]
-
-  draw.content(
-    (rel: (0, 1), to: "python-parser.north"),
-    padding: 5pt,
-    anchor: "south",
-    name: "source-py",
-  )[_`source.py`_]
-  arrow("source-py", "python-parser")
-
-  framed(
-    (rel: (3, 0), to: "python-parser.east"),
-    anchor: "west",
-    name: "custom-parser",
-    align(center)[Custom python\ parser],
-  )
-
-  arrow("python-parser", "custom-parser", name: "arrow-python-ast")
-  draw.content(
-    "arrow-python-ast",
-    anchor: "south",
-    padding: 5pt,
-  )[`ast.Module`]
-
-  framed(
-    (rel: (-3, -2), to: "custom-parser.south"),
-    anchor: "east",
-    name: "python-resolver",
-  )[Python Resolver]
-  arrow(
-    "custom-parser",
-    ((), "|-", "python-resolver.east"),
-    "python-resolver",
-    name: "arrow-python-custom-ast",
-  )
-  draw.content(
-    (rel: (1.5, 0), to: "arrow-python-custom-ast.end"),
-    padding: 5pt,
-    anchor: "south",
-  )[P-AST#footnote[#strong[P]ython *AST*]<fn-past>]
-  draw.content(
-    "python-resolver.west",
-    padding: 5pt,
-    anchor: "south-east",
-  )[Resolved P-AST@fn-past]
-
-  draw.circle(
-    (rel: (1, -2), to: "custom-parser.south-east"),
-    radius: .4,
-    name: "midas-loader",
-  )
-  arrow(
-    "custom-parser",
-    "midas-loader",
-    name: "arrow-load-midas",
-    mark: (end: (symbol: ">", fill: black), start: "o"),
-  )
-  draw.content(
-    "arrow-load-midas",
-    anchor: "west",
-    padding: 5pt,
-  )[```python midas.using("types.midas")```]
-
-  framed(
-    (rel: (0, -2), to: "midas-loader.south"),
-    name: "midas-parser",
-  )[Midas lexer/parser]
-  arrow("midas-loader", "midas-parser", name: "arrow-midas-source")
-  draw.content(
-    "arrow-midas-source",
-    anchor: "west",
-    padding: 5pt,
-  )[_`types.midas`_]
-
-
-  framed(
-    (rel: (-2, 0), to: "midas-parser.west"),
-    anchor: "east",
-    name: "midas-resolver",
-  )[Midas Resolver]
-  arrow("midas-parser", "midas-resolver", name: "arrow-midas-ast")
-  draw.content(
-    "arrow-midas-ast",
-    anchor: "south",
-    padding: 5pt,
-  )[M-AST#footnote[#strong[M]idas *AST*]<fn-mast>]
-
-  framed(
-    (rel: (-3, 0), to: "midas-resolver.west"),
-    anchor: "east",
-    name: "checker",
-  )[Checker]
-  arrow("midas-resolver", "checker", name: "arrow-type-ctx")
-  arrow(
-    "python-resolver",
-    ((), "-|", "checker.north"),
-    "checker",
-  )
-  draw.content(
-    "arrow-type-ctx",
-    anchor: "south",
-    padding: 5pt,
-  )[Types context]
-})
-
-#show: doc => if diagram-only {
-  set page(width: auto, height: auto, margin: .5cm)
-  diagram
-} else { doc }
-
-#align(center, title())
-
-#v(1cm)
-
-#figure(
-  diagram,
-  caption: [Midas type-checker architecture],
-)
-
-== Components
-
-- *Python parser*: builtin Python AST parser, extracts abstract syntax from the raw Python source (```python ast.parse(...)```)
-- *Custom python parser*: converts the raw Python AST into custom, more suitable constructs, especially for type annotations
-- *Python resolver*: resolves bindings and references, tracks binding scopes
-- *Midas lexer/parser*: parses a Midas type definition file and extracts its AST
-- *Midas resolver*: walks the AST and fills the environment with the defined types and operations
-- *Checker*: evaluates expressions and checks type coherence

examples/00_syntax_prototype/01_simple_types.py

@@ -1,16 +0,0 @@
-# type: ignore
-# ruff: disable[F821]
-from __future__ import annotations
-
-# A simple data-frame with different column of various simple types
-# Columns can be named and/or typed
-df: Frame[
-    verified: bool,
-    birth_year: int,
-    height: float + ( _ > 0 ) + ( _ < 250 ),
-    name: str,
-    date: datetime,
-    float,  # unnamed
-    unknown: _,  # untyped
-    _  # unnamed and untyped
-]

examples/00_syntax_prototype/02_custom_types.midas

@@ -1,24 +0,0 @@
-// Simple custom type derived from floats
-type Latitude<float>
-type Longitude<float>
-
-// Complex custom type, containing two values accessible through properties
-type GeoLocation<Latitude, Longitude> {
-    lat: Latitude
-    lon: Longitude
-}
-
-type LatitudeDiff<float>
-type LongitudeDiff<float>
-
-// Simple operation defined on our custom types
-op <Latitude> - <Latitude> = <LatitudeDiff>
-op <Longitude> - <Longitude> = <LongitudeDiff>
-
-// Simple custom type with a constraint
-type Age<int + (0 <= _) + (_ < 150)>
-
-// Predefined custom constraints that can be referenced in other definitions
-constraint Positive = _ >= 0
-constraint StrictlyPositive = _ > 0
-//constraint Even = _ % 2 == 0

examples/00_syntax_prototype/02_custom_types.py

@@ -1,30 +0,0 @@
-# type: ignore
-# ruff: disable[F821]
-from __future__ import annotations
-
-# A data-frame using a custom type
-df: Frame[
-    location: GeoLocation
-]
-
-# Properties of a type can be used on a column of that type
-lat: Column[GeoLocation] = df["location"].lat
-lon: Column[GeoLocation] = df["location"].lon
-
-# Unregistered operations between types are not permitted
-lat + lon  # Invalid operation
-
-# Registered operations are permitted
-lat1: Latitude = lat[0]
-lat2: Latitude = lat[1]
-lat_diff: Difference[Latitude] = lat2 - lat1  # Valid operation
-
-# In addition to the type, a column can have one or more constraints, either defined inline or in a separate file
-df2: Frame[
-    age: int + (_ >= 0),
-    height: float + (_ >= 0),
-]
-df2_bis: Frame[
-    age: int + Positive,
-    height: float + Positive,
-]

examples/00_syntax_prototype/03_custom_types_v2.midas

@@ -1,73 +0,0 @@
-// Simple custom type derived from float
-type Custom(float)
-
-// Simple custom types with constraints
-type Latitude(float) where (-90 <= _ <= 90)
-type Longitude(float) where (-180 <= _ <= 180)
-
-// Generic custom type (a Difference of T is derived from T, e.g. a difference of floats is a float
-type Difference[T](T)
-
-// Complex custom type, containing two values accessible through properties
-type GeoLocation {
-    lat: Latitude
-    lon: Longitude
-}
-
-// Define operations on our custom type
-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]
-}
-
-// For complex generics, you need to specify how the genericity the properties
-// are handled
-type Difference[GeoLocation] {
-    lat: Difference[Latitude]
-    lon: Difference[Longitude]
-}
-
-// Simple operation defined on our custom types
-extend Latitude {
-    op __sub__(Latitude) -> Difference[Latitude]
-}
-
-extend Longitude {
-    op __sub__(Longitude) -> Difference[Longitude]
-}
-
-// Predefined custom predicates that can be referenced in other definitions
-predicate Positive(v: float) = v >= 0
-predicate StrictlyPositive(v: float) = v > 0
-predicate Equatorial(loc: GeoLocation) = (-10 <= loc.lat <= 10)
-predicate Arctic(loc: GeoLocation) = (loc.lat >= 66)
-
-type Person {
-    name: str
-
-    // Property with an inline constraint
-    age: int? where (0 <= _ < 150)
-
-    // Property referencing a predicate
-    height: float where StrictlyPositive
-
-    home: GeoLocation
-}
-
-// Custom complex type derived from another complex type, with a constraint
-// on a property
-// Multiple proposed syntaxes, not yet defined
-
-// Explicit, but new keyword
-type EquatorialPerson refines Person where Equatorial(_.home)
-
-// Explicit with existing keyword, might be confusing if expectations regarding 'is'
-type EquatorialPerson is Person where Equatorial(_.home)
-
-// Consistent and Python-friendly but can be confused with structural extension
-type EquatorialPerson(Person) where Equatorial(_.home)
-
-// Allow new properties, probably not useful
-type EquatorialPerson extends Person where Equatorial(_.home)

examples/00_syntax_prototype/04_functions.py

@@ -1,15 +0,0 @@
-# type: ignore
-# ruff: disable[F821]
-from __future__ import annotations
-
-
-def func(
-    col1: Column[float + (0 <= _ <= 1)],
-    col2: Column[float + (0 <= _ <= 1)],
-) -> Column[float + (0 <= _ <= 2)]:
-    result: Column[float + (0 <= _ <= 2)] = col1 + col2
-    return result
-
-
-def func2(a: int, /, b: float, *, c: str):
-    pass

examples/00_syntax_prototype/05_custom_types_v3.midas

@@ -1,33 +0,0 @@
-type Foo1 = float
-type Foo2 = float where (_ > 3)
-type Foo3 = int | float
-type Foo4 = int where (_ > 3) | float where (_ > 3)
-type Foo5 = (int | float) where (_ > 3)
-type Foo6 = {
-    foo: float
-    bar: float where (_ > 3)
-}
-
-type Foo7[T] = T where (_ > 3)
-type Foo8[A, B<:int] = {
-    a: A
-    b: B
-}
-
-type Complex = {
-    a: int
-    b: int
-}
-type Complex2 = Complex where (_.a > 3 & _.b < 5)
-
-predicate Positive(n: int) = n >= 0
-
-extend Foo1 {
-    op __add__(Foo1) -> Foo1
-}
-
-extend Foo7[T] {
-    op __add__(Foo7[T]) -> Foo7[T]
-}
-
-type Optional[T] = None | T

examples/01_simple_type_checking/01_simple_operations.py

@@ -6,7 +6,7 @@ c = a + b  # -> int
 c = "invalid"  # -> can't assign str to int variable
 
 d = True
-e = d + d
+e = d + d  # -> addition not defined between booleans
 
 f: float = a
 

examples/01_simple_type_checking/02_simple_types.py

@@ -1,6 +1,7 @@
 # type: ignore
 # ruff: disable [F821]
 
-distance: Meter = cast(Meter, 123.45)
-time: Second = cast(Second, 6.7)
+distance = cast(Meter, 123.45)
+time = cast(Second, 6.7)
 speed = distance / time
+print(speed)

examples/01_simple_type_checking/03_control_flow.py

@@ -1,3 +1,5 @@
+# Return types must have a LUB
+# Valid
 def minimum(x: int, y: int):
     if x < y:
         return x
@@ -5,18 +7,28 @@ def minimum(x: int, y: int):
         return y
 
 
+# Invalid
+def func(a: int):
+    if a < 5:
+        return "Oops"
+    return True
+
+
 a = 15
 b = 72
 c = minimum(a, b)
 
 
+# Recursive but typable thanks to return hint
 def factorial(n: int) -> int:
     if n <= 1:
         return 1
     return n * factorial(n - 1)
 
 
-category = "Category 1" if a < 10 else "Category 2"
+# Branches must be of the same type
+category = "Category 1" if a < 10 else "Category 2"  # Valid
+category = "Category 1" if a < 10 else 3  # Invalid
 
 
 def foo() -> None:

examples/01_simple_type_checking/04_complex_types.midas

@@ -15,7 +15,9 @@ extend Coordinate {
 type Difference[T <: float] = T
 type MeterDifference = Difference[Meter]
 
-type CompDiff[T <: float] = {
+type CompDiff[T <: float] = object
+
+extend CompDiff[T <: float] {
     prop d1: Difference[T]
     prop d2: Difference[T]
 }

examples/01_simple_type_checking/04_complex_types.py

@@ -1,20 +1,20 @@
 # type: ignore
 # ruff: disable [F821]
 
-p1: Coordinate
-p2: Coordinate
+p1 = cast(Coordinate, object())
+p2 = cast(Coordinate, object())
 
 diff_x = p2.x - p1.x
 diff_y = p2.y - p1.y
 
 dist = diff_x + diff_y
 
-p2.x += cast(Meter, 1)
+p2.x += cast(Meter, 1.0)
 p2.y = True  # invalid, wrong type
 p2.z = 3  # invalid, no property 'z' on Coordinate
 p2.x.a = 3  # invalid, no properties on Meter
 
-foo: list[float] = []
+foo = cast(list[float], [])
 
 append = foo.append
 
@@ -23,7 +23,7 @@ foo.append(2)
 append(True)  # invalid, must be float
 append(2)
 
-bar: list[list[Meter]]
+bar = cast(list[list[Meter]], [])
 
 bar.append([p2.x])
 

examples/01_simple_type_checking/06_overloads.py

@@ -1,9 +1,9 @@
 # type: ignore
 # ruff: disable [F821]
 
-foo: Foo
-t1: T1
-t2: T2
+foo = cast(Foo, object())
+t1 = cast(T1, object())
+t2 = cast(T2, object())
 
 a = foo.bar(t1)
 b = foo.bar(t2)
@@ -13,6 +13,6 @@ func = foo.bar
 c = func(t1)
 d = func(t2)
 
-t2b: T2b
+t2b = cast(T2b, object())
 
 e = foo.bar(t2b)

examples/02_demonstration/demo_stubs.pyi

@@ -1,14 +0,0 @@
-from __future__ import annotations
-from typing import Generic, TypeVar
-
-class Currency(float): ...
-
-_T0 = TypeVar("_T0", bound=Currency, covariant=True)
-
-class Price(Currency, Generic[_T0]):
-    def __add__(self, _0: Price[_T0], /) -> Price[_T0]: ...
-
-class EUR(Currency): ...
-class USD(Currency): ...
-class CHF(Currency): ...
-class Discount(float): ...

justfile

@@ -0,0 +1,14 @@
+# Local Variables:
+# mode: makefile
+# End:
+set shell := ["bash", "-uc"]
+
+build-docs:
+  typst c --root . docs/manual.typ
+  typst c --root . docs/function_subtyping.typ
+
+tests:
+  uv run -m tests
+
+check-docstrings:
+  uv run scripts/docstring_checker.py

midas/checker/frames/column_groupby_methods.py

@@ -86,6 +86,9 @@ class ColumnGroupByMethodRegistry(MethodRegistry[Call]):
 
         # TODO: maybe better to filter arguments and pass some, in case the
         # return type depends on them
+
+        # Don't catch UndefinedMethodException because all aggregation
+        # methods should be defined on columns too
         returns: Type = self.typer.call_method(
             location=call.location,
             call_expr=call.call_expr,

midas/checker/frames/frame_groupby_methods.py

@@ -53,6 +53,8 @@ class FrameGroupByMethodRegistry(MethodRegistry[Call]):
         for column in call.groupby.frame.columns:
             with self.reporter.with_context(f"in column '{column.name}'"):
                 column_groupby: ColumnGroupBy = ColumnGroupBy(column=column.type)
+                # Don't catch UndefinedMethodException because all aggregation
+                # methods should be defined on columns too
                 result_type: Type = self.typer.call_method(
                     location=call.location,
                     call_expr=call.call_expr,

midas/checker/midas.py

@@ -170,7 +170,10 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
             type = GenericType(name=name, params=params, body=type)
         else:
             type = DerivedType(name=name, type=type)
-        self.types.define_type(name, type)
+        try:
+            self.types.define_type(name, type)
+        except ValueError:
+            self.reporter.error(stmt.location, f"Type {name} already defined")
         self._local_variables.clear()
         self._current_name = None
 
@@ -178,7 +181,10 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
         name: str = stmt.name.lexeme
         self._current_name = name
         type: Type = stmt.type.accept(self)
-        self.types.define_type(name, type)
+        try:
+            self.types.define_type(name, type)
+        except ValueError:
+            self.reporter.error(stmt.location, f"Type {name} already defined")
         self._current_name = None
 
     def visit_member_stmt(self, stmt: m.MemberStmt) -> None: ...
@@ -201,6 +207,7 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
             )
 
     def visit_predicate_stmt(self, stmt: m.PredicateStmt) -> None:
+        name: str = stmt.name.lexeme
         for spec in stmt.params:
             for param in spec.mixed:
                 assert param.name is not None
@@ -222,14 +229,17 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
                     returns=type,
                 )
         self._predicate_params = {}
-        self.types.define_predicate(
-            stmt.name.lexeme,
-            Predicate(
-                type=type,
-                body=stmt.body,
-                alias=len(params) == 0,
-            ),
-        )
+        try:
+            self.types.define_predicate(
+                name,
+                Predicate(
+                    type=type,
+                    body=stmt.body,
+                    alias=len(params) == 0,
+                ),
+            )
+        except ValueError:
+            self.reporter.error(stmt.location, f"Predicate {name} already defined")
 
     def _is_valid_predicate(self, body: Type) -> bool:
         """Check whether the given type is valid as a predicate's body

midas/checker/python.py

@@ -48,7 +48,9 @@ TypedExpr = tuple[p.Expr, Type]
 
 
 class ReturnException(Exception):
-    pass
+    def __init__(self, stmt: p.Stmt):
+        super().__init__()
+        self.stmt: p.Stmt = stmt
 
 
 class UndefinedMethodException(Exception):
@@ -116,7 +118,10 @@ class PythonTyper(
         self.judgements = []
         self.evaluated_casts = []
 
-        self.check(stmts)
+        try:
+            self.check(stmts)
+        except ReturnException as e:
+            self.reporter.error(e.stmt.location, "Return statement outside of function")
 
         return TypedAST(
             stmts=stmts,
@@ -576,7 +581,7 @@ class PythonTyper(
     def visit_return_stmt(self, stmt: p.ReturnStmt) -> None:
         type: Type = self.type_of(stmt.value) if stmt.value is not None else UnitType()
         self.env.return_types.append(type)
-        raise ReturnException()
+        raise ReturnException(stmt)
 
     def visit_if_stmt(self, stmt: p.IfStmt) -> None:
         # Not evaluated in sub-environment because assignments in the test leak out of the if
@@ -599,7 +604,7 @@ class PythonTyper(
         else_returned: bool = self.process_block(stmt.orelse, env)
         self.env.return_types.extend(env.return_types)
         if body_returned and else_returned:
-            raise ReturnException()
+            raise ReturnException(stmt)
 
     def visit_pass(self, stmt: p.Pass) -> None:
         pass
@@ -627,7 +632,7 @@ class PythonTyper(
         self.env = outer_env
 
         if body_returned:
-            raise ReturnException()
+            raise ReturnException(stmt)
 
     def visit_import_stmt(self, stmt: p.ImportStmt) -> None:
         self._visit_imports(stmt.location, stmt.imports)
@@ -772,14 +777,21 @@ class PythonTyper(
         match expr.callee:
             case p.GetExpr(object=obj, name=method):
                 obj_type: Type = self.type_of(obj)
-                return self.call_method(
-                    location=expr.location,
-                    call_expr=expr,
-                    obj=(obj, obj_type),
-                    method_name=method,
-                    positional=positional,
-                    keywords=keywords,
-                )
+                try:
+                    return self.call_method(
+                        location=expr.location,
+                        call_expr=expr,
+                        obj=(obj, obj_type),
+                        method_name=method,
+                        positional=positional,
+                        keywords=keywords,
+                    )
+                except UndefinedMethodException:
+                    self.reporter.error(
+                        expr.location,
+                        f"Unknown method {method} on type {obj_type}",
+                    )
+                    return UnknownType()
 
         callee: Type = self.type_of(expr.callee)
         result: CallResult = self.dispatcher.get_result(
@@ -1001,7 +1013,11 @@ class PythonTyper(
 
         if len(node.args) != 0:
             args: list[Type] = [self.resolve_type_expr(arg) for arg in node.args]
-            return self.types.apply_generic(base, args)
+            try:
+                return self.types.apply_generic(base, args)
+            except Exception as e:
+                self.reporter.error(node.location, f"Cannot apply generic type: {e}")
+                return UnknownType()
         return base
 
     def visit_frame_column(self, node: p.FrameColumn) -> ColumnType:
@@ -1078,10 +1094,13 @@ class PythonTyper(
                 bound: Optional[Type] = None
                 variance: Variance = Variance.INVARIANT
                 if "bound" in call.keywords:
-                    bound_type: p.MidasType = self._parse_type_from_expr(
-                        call.keywords["bound"]
-                    )
-                    bound = self.resolve_type_expr(bound_type)
+                    try:
+                        bound_type: p.MidasType = self._parse_type_from_expr(
+                            call.keywords["bound"]
+                        )
+                        bound = self.resolve_type_expr(bound_type)
+                    except NotImplementedError:
+                        bound = UnknownType()
 
                 if is_kw_true("covariant"):
                     variance = Variance.COVARIANT
@@ -1096,7 +1115,13 @@ class PythonTyper(
                     else:
                         variance = Variance.CONTRAVARIANT
                 var: TypeVar = TypeVar(name=name, bound=bound, variance=variance)
-                self.types.define_type(name, var)
+                try:
+                    self.types.define_type(name, var)
+                except ValueError:
+                    self.reporter.error(
+                        call.location,
+                        f"A type or type variable with the name {name} is already defined",
+                    )
                 return var
 
             case _:
@@ -1127,6 +1152,14 @@ class PythonTyper(
                 return parser._parse_type(node.body)
             case p.VariableExpr(name=name):
                 return p.BaseType(location=location, base=name, args=())
+            case p.SubscriptExpr(object=p.VariableExpr(name=name), index=arg):
+                args: tuple[p.MidasType, ...] = (
+                    tuple(self._parse_type_from_expr(a) for a in arg.items)
+                    if isinstance(arg, p.TupleExpr)
+                    else (self._parse_type_from_expr(arg),)
+                )
+                return p.BaseType(location=location, base=name, args=args)
+
             case _:
                 raise NotImplementedError
 

midas/checker/types.py

@@ -362,9 +362,6 @@ def substitute_typevars(type: Type, substitutions: dict[str, Type]) -> Type:
         case UnknownType() | UnitType():
             return type
 
-        case TopType() | GenericType():
-            raise NotImplementedError(f"Unsupported type {type}")
-
         # Ensure exhaustiveness
         case _:
             assert_never(type)

test.py

@@ -1,33 +0,0 @@
-import json
-from pathlib import Path
-
-from midas.ast.printer import MidasAstPrinter
-from midas.lexer.midas import MidasLexer
-from midas.lexer.token import Token
-from midas.parser.midas import MidasParser
-
-
-def test_midas():
-    # Midas type definitions
-    path: Path = Path("examples") / "00_syntax_prototype" / "03_custom_types_v2.midas"
-    definitions: str = path.read_text()
-    midas_lexer: MidasLexer = MidasLexer(definitions, path.name)
-    tokens: list[Token] = midas_lexer.process()
-    # print([f"{t.type.name}('{t.lexeme}')" for t in tokens])
-    with open("tokens.json", "w") as f:
-        json.dump([f"{t.type.name}('{t.lexeme}')" for t in tokens], f, indent=4)
-
-    parser = MidasParser(tokens)
-    parsed = parser.parse()
-    print(parsed)
-    for err in parser.errors:
-        print(err.get_report())
-    printer = MidasAstPrinter()
-    for stmt in parsed:
-        if stmt is None:
-            print("None")
-            continue
-        print(printer.print(stmt))
-
-
-test_midas()

tests/cases/midas-parser/01_simple_types.midas

@@ -2,8 +2,8 @@
 type Custom = float
 
 // Simple custom types with constraints
-type Latitude = float where (-90 <= _ <= 90)
-type Longitude = float where (-180 <= _ <= 180)
+type Latitude = float where (-90 <= _ & _ <= 90)
+type Longitude = float where (-180 <= _ & _ <= 180)
 
 // Generic custom type (a Difference of T is derived from T, e.g. a difference of floats is a float
 type Difference[T] = T
@@ -54,10 +54,10 @@ extend Person {
     prop name: str
 
     // Property with an inline constraint
-    prop age: Optional[int where (0 <= _ < 150)]
+    prop age: int where (0 <= _ & _ < 150)
 
     // Property referencing a predicate
-    prop height: float where StrictlyPositive
+    prop height: float where StrictlyPositive(_)
 
     prop home: GeoLocation
 }

tests/cases/midas-parser/01_simple_types.midas.ref.json

@@ -187,8 +187,8 @@
       "column": 38
     },
     {
-      "type": "LESS_EQUAL",
-      "lexeme": "<=",
+      "type": "AND",
+      "lexeme": "&",
       "line": 5,
       "column": 39
     },
@@ -196,25 +196,49 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 5,
+      "column": 40
+    },
+    {
+      "type": "UNDERSCORE",
+      "lexeme": "_",
+      "line": 5,
       "column": 41
     },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 5,
+      "column": 42
+    },
+    {
+      "type": "LESS_EQUAL",
+      "lexeme": "<=",
+      "line": 5,
+      "column": 43
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 5,
+      "column": 45
+    },
     {
       "type": "NUMBER",
       "lexeme": "90",
       "line": 5,
-      "column": 42
+      "column": 46
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 5,
-      "column": 44
+      "column": 48
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 5,
-      "column": 45
+      "column": 49
     },
     {
       "type": "TYPE",
@@ -325,8 +349,8 @@
       "column": 40
     },
     {
-      "type": "LESS_EQUAL",
-      "lexeme": "<=",
+      "type": "AND",
+      "lexeme": "&",
       "line": 6,
       "column": 41
     },
@@ -334,25 +358,49 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 6,
+      "column": 42
+    },
+    {
+      "type": "UNDERSCORE",
+      "lexeme": "_",
+      "line": 6,
       "column": 43
     },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 6,
+      "column": 44
+    },
+    {
+      "type": "LESS_EQUAL",
+      "lexeme": "<=",
+      "line": 6,
+      "column": 45
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 6,
+      "column": 47
+    },
     {
       "type": "NUMBER",
       "lexeme": "180",
       "line": 6,
-      "column": 44
+      "column": 48
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 6,
-      "column": 47
+      "column": 51
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 6,
-      "column": 48
+      "column": 52
     },
     {
       "type": "NEWLINE",
@@ -2240,22 +2288,40 @@
     },
     {
       "type": "IDENTIFIER",
-      "lexeme": "Optional",
+      "lexeme": "int",
       "line": 57,
       "column": 15
     },
     {
-      "type": "LEFT_BRACKET",
-      "lexeme": "[",
+      "type": "WHITESPACE",
+      "lexeme": " ",
       "line": 57,
-      "column": 23
+      "column": 18
     },
     {
-      "type": "IDENTIFIER",
-      "lexeme": "int",
+      "type": "WHERE",
+      "lexeme": "where",
+      "line": 57,
+      "column": 19
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
       "line": 57,
       "column": 24
     },
+    {
+      "type": "LEFT_PAREN",
+      "lexeme": "(",
+      "line": 57,
+      "column": 25
+    },
+    {
+      "type": "NUMBER",
+      "lexeme": "0",
+      "line": 57,
+      "column": 26
+    },
     {
       "type": "WHITESPACE",
       "lexeme": " ",
@@ -2263,8 +2329,8 @@
       "column": 27
     },
     {
-      "type": "WHERE",
-      "lexeme": "where",
+      "type": "LESS_EQUAL",
+      "lexeme": "<=",
       "line": 57,
       "column": 28
     },
@@ -2272,17 +2338,35 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 57,
+      "column": 30
+    },
+    {
+      "type": "UNDERSCORE",
+      "lexeme": "_",
+      "line": 57,
+      "column": 31
+    },
+    {
+      "type": "WHITESPACE",
+      "lexeme": " ",
+      "line": 57,
+      "column": 32
+    },
+    {
+      "type": "AND",
+      "lexeme": "&",
+      "line": 57,
       "column": 33
     },
     {
-      "type": "LEFT_PAREN",
-      "lexeme": "(",
+      "type": "WHITESPACE",
+      "lexeme": " ",
       "line": 57,
       "column": 34
     },
     {
-      "type": "NUMBER",
-      "lexeme": "0",
+      "type": "UNDERSCORE",
+      "lexeme": "_",
       "line": 57,
       "column": 35
     },
@@ -2293,8 +2377,8 @@
       "column": 36
     },
     {
-      "type": "LESS_EQUAL",
-      "lexeme": "<=",
+      "type": "LESS",
+      "lexeme": "<",
       "line": 57,
       "column": 37
     },
@@ -2302,55 +2386,25 @@
       "type": "WHITESPACE",
       "lexeme": " ",
       "line": 57,
-      "column": 39
-    },
-    {
-      "type": "UNDERSCORE",
-      "lexeme": "_",
-      "line": 57,
-      "column": 40
-    },
-    {
-      "type": "WHITESPACE",
-      "lexeme": " ",
-      "line": 57,
-      "column": 41
-    },
-    {
-      "type": "LESS",
-      "lexeme": "<",
-      "line": 57,
-      "column": 42
-    },
-    {
-      "type": "WHITESPACE",
-      "lexeme": " ",
-      "line": 57,
-      "column": 43
+      "column": 38
     },
     {
       "type": "NUMBER",
       "lexeme": "150",
       "line": 57,
-      "column": 44
+      "column": 39
     },
     {
       "type": "RIGHT_PAREN",
       "lexeme": ")",
       "line": 57,
-      "column": 47
-    },
-    {
-      "type": "RIGHT_BRACKET",
-      "lexeme": "]",
-      "line": 57,
-      "column": 48
+      "column": 42
     },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 57,
-      "column": 49
+      "column": 43
     },
     {
       "type": "NEWLINE",
@@ -2442,11 +2496,29 @@
       "line": 60,
       "column": 30
     },
+    {
+      "type": "LEFT_PAREN",
+      "lexeme": "(",
+      "line": 60,
+      "column": 46
+    },
+    {
+      "type": "UNDERSCORE",
+      "lexeme": "_",
+      "line": 60,
+      "column": 47
+    },
+    {
+      "type": "RIGHT_PAREN",
+      "lexeme": ")",
+      "line": 60,
+      "column": 48
+    },
     {
       "type": "NEWLINE",
       "lexeme": "\n",
       "line": 60,
-      "column": 46
+      "column": 49
     },
     {
       "type": "NEWLINE",
@@ -2544,7 +2616,7 @@
         "constraint": {
           "_type": "GroupingExpr",
           "expr": {
-            "_type": "BinaryExpr",
+            "_type": "LogicalExpr",
             "left": {
               "_type": "BinaryExpr",
               "left": {
@@ -2560,10 +2632,17 @@
                 "_type": "WildcardExpr"
               }
             },
-            "operator": "<=",
+            "operator": "&",
             "right": {
-              "_type": "LiteralExpr",
-              "value": 90
+              "_type": "BinaryExpr",
+              "left": {
+                "_type": "WildcardExpr"
+              },
+              "operator": "<=",
+              "right": {
+                "_type": "LiteralExpr",
+                "value": 90
+              }
             }
           }
         }
@@ -2582,7 +2661,7 @@
         "constraint": {
           "_type": "GroupingExpr",
           "expr": {
-            "_type": "BinaryExpr",
+            "_type": "LogicalExpr",
             "left": {
               "_type": "BinaryExpr",
               "left": {
@@ -2598,10 +2677,17 @@
                 "_type": "WildcardExpr"
               }
             },
-            "operator": "<=",
+            "operator": "&",
             "right": {
-              "_type": "LiteralExpr",
-              "value": 180
+              "_type": "BinaryExpr",
+              "left": {
+                "_type": "WildcardExpr"
+              },
+              "operator": "<=",
+              "right": {
+                "_type": "LiteralExpr",
+                "value": 180
+              }
             }
           }
         }
@@ -3013,42 +3099,40 @@
           "kind": "PROPERTY",
           "name": "age",
           "type": {
-            "_type": "GenericType",
+            "_type": "ConstraintType",
             "type": {
               "_type": "NamedType",
-              "name": "Optional"
+              "name": "int"
             },
-            "args": [
-              {
-                "_type": "ConstraintType",
-                "type": {
-                  "_type": "NamedType",
-                  "name": "int"
+            "constraint": {
+              "_type": "GroupingExpr",
+              "expr": {
+                "_type": "LogicalExpr",
+                "left": {
+                  "_type": "BinaryExpr",
+                  "left": {
+                    "_type": "LiteralExpr",
+                    "value": 0
+                  },
+                  "operator": "<=",
+                  "right": {
+                    "_type": "WildcardExpr"
+                  }
                 },
-                "constraint": {
-                  "_type": "GroupingExpr",
-                  "expr": {
-                    "_type": "BinaryExpr",
-                    "left": {
-                      "_type": "BinaryExpr",
-                      "left": {
-                        "_type": "LiteralExpr",
-                        "value": 0
-                      },
-                      "operator": "<=",
-                      "right": {
-                        "_type": "WildcardExpr"
-                      }
-                    },
-                    "operator": "<",
-                    "right": {
-                      "_type": "LiteralExpr",
-                      "value": 150
-                    }
+                "operator": "&",
+                "right": {
+                  "_type": "BinaryExpr",
+                  "left": {
+                    "_type": "WildcardExpr"
+                  },
+                  "operator": "<",
+                  "right": {
+                    "_type": "LiteralExpr",
+                    "value": 150
                   }
                 }
               }
-            ]
+            }
           }
         },
         {
@@ -3062,8 +3146,17 @@
               "name": "float"
             },
             "constraint": {
-              "_type": "VariableExpr",
-              "name": "StrictlyPositive"
+              "_type": "CallExpr",
+              "callee": {
+                "_type": "VariableExpr",
+                "name": "StrictlyPositive"
+              },
+              "arguments": [
+                {
+                  "_type": "WildcardExpr"
+                }
+              ],
+              "keywords": {}
             }
           }
         },