feat(checker): add context to reports

examples/02_demonstration/weather/custom_types.midas

@@ -5,7 +5,7 @@ type Celsius = float
 type Kelvin = float where _ >= 0
 type Hectopascal = float
 
-type Temperature = Celsius where in_range(-30.0, 100.0)
+type Temperature = Celsius where in_range(-30.0, 100.0)(_)
 type Pressure = Hectopascal where in_range(800.0, 1100.0)(_)
 type Humidity = float where is_percentage(_)
 type HeatIndex = float
@@ -61,5 +61,5 @@ alias DailyAverages = Frame[
     heat_index: Mean[HeatIndex],
 ]
 
-predicate limit_amplitude(max_amp: float)(ls: list[float]) = max(ls) - min(ls) <= max_amp
-type LowAmplitudeWave = list[float where _ >= 1] where limit_amplitude(10)(_)
+// predicate limit_amplitude(max_amp: float)(ls: list[float]) = max(ls) - min(ls) <= max_amp
+// type LowAmplitudeWave = list[float where _ >= 1] where limit_amplitude(10)(_)

examples/02_demonstration/weather/gen_data.py

@@ -11,7 +11,7 @@ delta = end_ts - start_ts
 
 min_temp, max_temp = -30.0, 100.0
 min_pres, max_pres = 800.0, 1100.0
-min_hum, max_hum = 0.0, 1.0
+min_hum, max_hum = 0.0, 100.0
 
 N = 3000
 

midas/checker/frames/frame_groupby_methods.py

@@ -51,6 +51,7 @@ class FrameGroupByMethodRegistry(MethodRegistry[Call]):
         new_columns: list[DataFrameType.Column] = []
 
         for column in call.groupby.frame.columns:
+            with self.reporter.with_context(f"in column '{column.name}'"):
                 column_groupby: ColumnGroupBy = ColumnGroupBy(column=column.type)
                 result_type: Type = self.typer.call_method(
                     location=call.location,

midas/checker/frames/frame_methods.py

@@ -159,7 +159,10 @@ class FrameMethodRegistry(MethodRegistry[Call]):
                 col_type2 = ColumnType(type=operand[1])
 
             if col_type2 is not None:
-                col_type = self._get_method_result(call, col_type1, col_type2, method)
+                with self.reporter.with_context(f"in column '{column.name}'"):
+                    col_type = self._get_method_result(
+                        call, col_type1, col_type2, method
+                    )
 
             new_column = DataFrameType.Column(
                 index=column.index,

midas/checker/midas.py

@@ -407,8 +407,18 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
             return UnknownType()
 
     def visit_constraint_type(self, type: m.ConstraintType) -> Type:
+        base_type: Type = type.type.accept(self)
+        self._predicate_params["_"] = base_type
+        constraint_type: Type = self.type_of(type.constraint)
+        self._predicate_params = {}
+        if not self.types.is_subtype(constraint_type, self._bool):
+            self.reporter.error(
+                type.location,
+                f"Constraint must evaluate to a boolean, got {constraint_type}",
+            )
+
         return ConstraintType(
-            type=type.type.accept(self),
+            type=base_type,
             constraint=type.constraint,
         )
 

midas/checker/reporter.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from contextlib import contextmanager
 from typing import Optional
 
 from midas.ast.location import Location
@@ -54,6 +55,7 @@ class FileReporter:
     def __init__(self, base_reporter: Reporter, path: Optional[str]) -> None:
         self.base_reporter: Reporter = base_reporter
         self.path: Optional[str] = path
+        self._context: list[str] = []
 
     def for_file(self, path: Optional[str]) -> FileReporter:
         """Create a new file reporter for the given path with the same base reporter
@@ -66,6 +68,14 @@ class FileReporter:
         """
         return FileReporter(self.base_reporter, path)
 
+    @contextmanager
+    def with_context(self, ctx: str):
+        self._context.append(ctx)
+        try:
+            yield
+        finally:
+            self._context.pop()
+
     def report(self, type: DiagnosticType, location: Location, message: str):
         """Report a diagnostic to the base reporter
 
@@ -74,6 +84,8 @@ class FileReporter:
             location (Location): the location of the diagnostic in the file
             message (str): the diagnostic's message
         """
+        for ctx in self._context:
+            message = message + ", " + ctx
         self.base_reporter.report(self.path, type, location, message)
 
     def error(self, location: Location, message: str):