diff --git a/gen/python.py b/gen/python.py
index 2e6c7d3..99b926d 100644
--- a/gen/python.py
+++ b/gen/python.py
@@ -86,6 +86,12 @@ class Pass:
     pass
 
 
+class ForStmt:
+    target: Expr
+    iterator: Expr
+    body: list[Stmt]
+
+
 ###<
 
 
diff --git a/midas/ast/printer.py b/midas/ast/printer.py
index 77a6069..364da35 100644
--- a/midas/ast/printer.py
+++ b/midas/ast/printer.py
@@ -596,6 +596,23 @@ class PythonAstPrinter(
     def visit_pass(self, stmt: p.Pass) -> None:
         self._write_line("Pass")
 
+    def visit_for_stmt(self, stmt: p.ForStmt) -> None:
+        self._write_line("ForStmt")
+        with self._child_level():
+            self._write_line("target")
+            with self._child_level(single=True):
+                stmt.target.accept(self)
+            self._write_line("iterator")
+            with self._child_level(single=True):
+                stmt.iterator.accept(self)
+            self._write_line("body", last=True)
+            with self._child_level():
+                for i, body_stmt in enumerate(stmt.body):
+                    self._idx = i
+                    if i == len(stmt.body) - 1:
+                        self._mark_last()
+                    body_stmt.accept(self)
+
     def visit_binary_expr(self, expr: p.BinaryExpr) -> None:
         self._write_line("BinaryExpr")
         with self._child_level():
diff --git a/midas/ast/python.py b/midas/ast/python.py
index f3c9e1c..b781d2e 100644
--- a/midas/ast/python.py
+++ b/midas/ast/python.py
@@ -110,6 +110,9 @@ class Stmt(ABC):
         @abstractmethod
         def visit_pass(self, stmt: Pass) -> T: ...
 
+        @abstractmethod
+        def visit_for_stmt(self, stmt: ForStmt) -> T: ...
+
 
 @dataclass(frozen=True)
 class ExpressionStmt(Stmt):
@@ -189,6 +192,16 @@ class Pass(Stmt):
         return visitor.visit_pass(self)
 
 
+@dataclass(frozen=True)
+class ForStmt(Stmt):
+    target: Expr
+    iterator: Expr
+    body: list[Stmt]
+
+    def accept(self, visitor: Stmt.Visitor[T]) -> T:
+        return visitor.visit_for_stmt(self)
+
+
 ###############
 # Expressions #
 ###############
diff --git a/midas/checker/python.py b/midas/checker/python.py
index d667164..316836e 100644
--- a/midas/checker/python.py
+++ b/midas/checker/python.py
@@ -78,17 +78,37 @@ class PythonTyper(
 
         return TypedAST(stmts=stmts, judgements=self.judgements)
 
-    def type_of(self, expr: p.Expr) -> Type:
+    def judge(self, expr: p.Expr, type: Type):
+        """Record a typing judgement
+
+        Args:
+            expr (p.Expr): the judged expression
+            type (Type): the type of the expression
+        """
+        self.judgements.append((expr, type))
+
+    def compute_type(self, expr: p.Expr) -> Type:
         """Evaluate the type of an expression
 
+        Args:
+            expr (p.Expr): the expression to type
+
+        Returns:
+            Type: the type of the given expression
+        """
+        return expr.accept(self)
+
+    def type_of(self, expr: p.Expr) -> Type:
+        """Evaluate the type of an expression and record the judgement
+
         Args:
             expr (p.Expr): the expression to evaluate
 
         Returns:
             Type: the type of the given expression
         """
-        type: Type = expr.accept(self)
-        self.judgements.append((expr, type))
+        type: Type = self.compute_type(expr)
+        self.judge(expr, type)
         return type
 
     def resolve_type_expr(self, expr: p.MidasType) -> Type:
@@ -334,6 +354,22 @@ class PythonTyper(
     def visit_pass(self, stmt: p.Pass) -> None:
         pass
 
+    def visit_for_stmt(self, stmt: p.ForStmt) -> None:
+        item_type: Optional[Type] = self._get_iterator_type(stmt.iterator)
+        if item_type is None:
+            iterator_type: Type = self.compute_type(stmt.iterator)
+            self.reporter.error(
+                stmt.iterator.location, f"{iterator_type} is not iterable"
+            )
+            item_type = UnknownType()
+
+        self._assign(stmt.location, stmt.target, item_type)
+        self.judge(stmt.target, item_type)
+        env: Environment = Environment(self.env)
+        body_returned: bool = self.process_block(stmt.body, env)
+        if body_returned:
+            raise ReturnException()
+
     def visit_binary_expr(self, expr: p.BinaryExpr) -> Type:
         method: Optional[str] = OPERATOR_METHODS.get(expr.operator.__class__)
         if method is None:
@@ -370,7 +406,13 @@ class PythonTyper(
             )
             return UnknownType()
 
-        return self._get_call_result(location, operation, [(right_expr, right)], {})
+        result: Optional[Type] = self._get_call_result(
+            location,
+            operation,
+            [(right_expr, right)],
+            {},
+        )
+        return result or UnknownType()
 
     def visit_unary_expr(self, expr: p.UnaryExpr) -> Type:
         method: Optional[str] = UNARY_METHODS.get(expr.operator.__class__)
@@ -390,9 +432,13 @@ class PythonTyper(
             )
             return UnknownType()
 
-        return self._get_call_result(
-            expr.location, operation, [(expr.right, operand)], {}
+        result: Optional[Type] = self._get_call_result(
+            expr.location,
+            operation,
+            [],
+            {},
         )
+        return result or UnknownType()
 
     def visit_call_expr(self, expr: p.CallExpr) -> Type:
         callee: Type = self.type_of(expr.callee)
@@ -402,11 +448,14 @@ class PythonTyper(
         keywords: dict[str, TypedExpr] = {
             name: (arg, self.type_of(arg)) for name, arg in expr.keywords.items()
         }
-        return self._get_call_result(
-            location=expr.location,
-            callee=callee,
-            positional=positional,
-            keywords=keywords,
+        return (
+            self._get_call_result(
+                location=expr.location,
+                callee=callee,
+                positional=positional,
+                keywords=keywords,
+            )
+            or UnknownType()
         )
 
     def visit_get_expr(self, expr: p.GetExpr) -> Type:
@@ -509,8 +558,9 @@ class PythonTyper(
             return UnknownType()
 
         index: Type = self.type_of(expr.index)
-        return self._get_call_result(
-            expr.location, operation, [(expr.index, index)], {}
+        return (
+            self._get_call_result(expr.location, operation, [(expr.index, index)], {})
+            or UnknownType()
         )
 
     def visit_slice_expr(self, expr: p.SliceExpr) -> Type:
@@ -547,7 +597,8 @@ class PythonTyper(
         callee: Type,
         positional: list[TypedExpr],
         keywords: dict[str, TypedExpr],
-    ) -> Type:
+        report_errors: bool = True,
+    ) -> Optional[Type]:
         """Get the result type of a function call
 
         If the function has overloads, the function will try to resolve the
@@ -561,9 +612,10 @@ class PythonTyper(
             callee (Type): the called function
             positional (list[TypedExpr]): the list positional arguments
             keywords (dict[str, TypedExpr]): the map of keyword arguments
+            report_errors (bool, optional): whether type errors should be reported as diagnostics. Defaults to True.
 
         Returns:
-            Type: the return type of the call, or `UnknownType` if either
+            Type: the return type of the call, or `None` if either
             the call is invalid or no overload matched the arguments uniquely
         """
         match callee:
@@ -573,21 +625,22 @@ class PythonTyper(
                 valid, mapped = self.map_call_arguments(
                     function, location, positional, keywords
                 )
-                valid = valid and self._are_arguments_valid(mapped)
+                valid = valid and self._are_arguments_valid(mapped, report_errors)
                 if not valid:
-                    return UnknownType()
+                    return None
                 return function.returns
 
             case OverloadedFunction(overloads=overloads):
                 function = self._match_overload(
-                    overloads, location, positional, keywords
+                    overloads, location, positional, keywords, report_errors
                 )
                 if function is None:
-                    return UnknownType()
+                    return None
                 return function.returns
             case _:
-                self.reporter.error(location, f"{callee} is not callable")
-                return UnknownType()
+                if report_errors:
+                    self.reporter.error(location, f"{callee} is not callable")
+                return None
 
     def _are_arguments_valid(
         self,
@@ -620,6 +673,7 @@ class PythonTyper(
         location: Location,
         positional: list[TypedExpr],
         keywords: dict[str, TypedExpr],
+        report_errors: bool = True,
     ) -> Optional[Function]:
         """Try and resolve the appropriate overload for the given arguments
 
@@ -628,6 +682,7 @@ class PythonTyper(
             location (Location): the call location
             positional (list[TypedExpr]): the list of positional arguments
             keywords (dict[str, TypedExpr]): the map of keywords arguments
+            report_errors (bool, optional): whether type errors should be reported as diagnostics. Defaults to True.
 
         Returns:
             Optional[Function]: the resolved function signature if it can be
@@ -637,9 +692,10 @@ class PythonTyper(
         for overload in overloads:
             function: Type = unfold_type(overload)
             if not isinstance(function, Function):
-                self.logger.error(
-                    f"Overload is not a function: {overload} is {function}"
-                )
+                if report_errors:
+                    self.logger.error(
+                        f"Overload is not a function: {overload} is {function}"
+                    )
                 continue
             valid, mapped = self.map_call_arguments(
                 function=function,
@@ -671,10 +727,11 @@ class PythonTyper(
         # No match -> invalid call
         if n_candidates == 0:
             overloads_str: str = ", ".join(map(str, overloads))
-            self.reporter.error(
-                location,
-                f"No matching overload in [{overloads_str}] {for_args}",
-            )
+            if report_errors:
+                self.reporter.error(
+                    location,
+                    f"No matching overload in [{overloads_str}] {for_args}",
+                )
             return None
 
         # Multiple matches -> see if one <: all others (more specific)
@@ -695,10 +752,11 @@ class PythonTyper(
         candidates_str: str = ", ".join(
             str(candidate.function) for candidate in candidates
         )
-        self.reporter.error(
-            location,
-            f"Multiple matching overloads {for_args}: {candidates_str}",
-        )
+        if report_errors:
+            self.reporter.error(
+                location,
+                f"Multiple matching overloads {for_args}: {candidates_str}",
+            )
         return None
 
     def map_call_arguments(
@@ -863,3 +921,21 @@ class PythonTyper(
             if not self.is_subtype(type1, type2):
                 return False
         return True
+
+    def _get_iterator_type(self, expr: p.Expr) -> Optional[Type]:
+        # TODO: lookup __iter__
+        type: Type = self.type_of(expr)
+        getitem: Optional[Type] = self.types.lookup_member(type, "__getitem__")
+        if getitem is None:
+            return None
+
+        index: p.Expr = p.LiteralExpr(location=expr.location, value=0)
+        index_type: Type = self.compute_type(index)
+        result: Optional[Type] = self._get_call_result(
+            location=expr.location,
+            callee=getitem,
+            positional=[(index, index_type)],
+            keywords={},
+            report_errors=False,
+        )
+        return result
diff --git a/midas/checker/resolver.py b/midas/checker/resolver.py
index eb0a6e8..c99a18d 100644
--- a/midas/checker/resolver.py
+++ b/midas/checker/resolver.py
@@ -116,17 +116,20 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
     def visit_assign_stmt(self, stmt: p.AssignStmt) -> None:
         self.resolve(stmt.value)
         for target in stmt.targets:
-            match target:
-                case p.VariableExpr(name=name):
-                    if not self.is_defined(name):
-                        self.declare(name)
-                        self.define(name)
-                    target.accept(self)
+            self._visit_assign(target)
 
-                case p.GetExpr():
-                    target.accept(self)
-                case _:
-                    raise Exception(f"Unsupported assignment to {target}")
+    def _visit_assign(self, target: p.Expr):
+        match target:
+            case p.VariableExpr(name=name):
+                if not self.is_defined(name):
+                    self.declare(name)
+                    self.define(name)
+                target.accept(self)
+
+            case p.GetExpr():
+                target.accept(self)
+            case _:
+                raise Exception(f"Unsupported assignment to {target}")
 
     def visit_return_stmt(self, stmt: p.ReturnStmt) -> None:
         if stmt.value is not None:
@@ -153,6 +156,13 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
     def visit_pass(self, stmt: p.Pass) -> None:
         pass
 
+    def visit_for_stmt(self, stmt: p.ForStmt) -> None:
+        self.resolve(stmt.iterator)
+        self._visit_assign(stmt.target)
+        self.begin_scope()
+        self.resolve(*stmt.body)
+        self.end_scope()
+
     def visit_binary_expr(self, expr: p.BinaryExpr) -> None:
         self.resolve(expr.left)
         self.resolve(expr.right)
diff --git a/midas/cli/commands/check.py b/midas/cli/commands/check.py
index f59c479..22f654e 100644
--- a/midas/cli/commands/check.py
+++ b/midas/cli/commands/check.py
@@ -14,7 +14,7 @@ from midas.cli.highlighter import DiagnosticsHighlighter
 from midas.cli.utils import DiagnosticPrinter
 
 
-@click.command()
+@click.command(help="Run type checker and report diagnostics")
 @click.argument("file", type=click.File("r"))
 @click.option("-t", "--types", type=click.File("r"), multiple=True)
 @click.option("-l", "--highlight", type=click.File("w"))
diff --git a/midas/cli/commands/compile.py b/midas/cli/commands/compile.py
index 7d495fc..5a410f7 100644
--- a/midas/cli/commands/compile.py
+++ b/midas/cli/commands/compile.py
@@ -3,19 +3,20 @@
 # midas compile <file.py> [--types <file.midas>] [-o <output>] [--assertions|--strict|--no-checks]
 # ```
 
+import sys
 from pathlib import Path
 from typing import TextIO
 
 import click
 
 from midas.checker.checker import TypeChecker
-from midas.checker.diagnostic import Diagnostic
+from midas.checker.diagnostic import Diagnostic, DiagnosticType
 from midas.cli.utils import DiagnosticPrinter
 from midas.generator.generator import Generator
 from midas.utils import TypedAST
 
 
-@click.command()
+@click.command(help="Compile source")
 @click.argument("file", type=click.File("r"))
 @click.option("-t", "--types", type=click.File("r"), multiple=True)
 def compile(
@@ -34,5 +35,8 @@ def compile(
     printer = DiagnosticPrinter()
     printer.print_all(diagnostics)
 
+    if any(map(lambda d: d.type == DiagnosticType.ERROR, diagnostics)):
+        sys.exit(1)
+
     generator = Generator(workdir=source_path.parent)
     generator.generate(typed_ast, source_path)
diff --git a/midas/cli/commands/format.py b/midas/cli/commands/format.py
index ce570c0..1bd3dbf 100644
--- a/midas/cli/commands/format.py
+++ b/midas/cli/commands/format.py
@@ -9,7 +9,7 @@ from midas.lexer.token import Token
 from midas.parser.midas import MidasParser
 
 
-@click.command()
+@click.command(help="Parse and pretty print a Midas file")
 @click.argument("file", type=click.File("r"))
 @click.option("-o", "--output", type=click.File("w"), default="-")
 def format(file: TextIO, output: TextIO):
diff --git a/midas/cli/commands/highlight.py b/midas/cli/commands/highlight.py
index acb05e9..cf04a8d 100644
--- a/midas/cli/commands/highlight.py
+++ b/midas/cli/commands/highlight.py
@@ -46,7 +46,10 @@ def highlight_midas(source: str, path: str) -> Highlighter:
     return highlighter
 
 
-@click.command()
+@click.command(
+    help="Parse a Python or Midas file and produce a highlighted version showing AST node types inline",
+    short_help="Parse and highlight a Python or Midas file",
+)
 @click.argument("file", type=click.File("r"))
 @click.option("-o", "--output", type=click.File("w"), default="-")
 def highlight(output: TextIO, file: TextIO):
diff --git a/midas/cli/commands/parse.py b/midas/cli/commands/parse.py
index c2a2f1a..d2f5338 100644
--- a/midas/cli/commands/parse.py
+++ b/midas/cli/commands/parse.py
@@ -45,7 +45,7 @@ def dump_midas_ast(source: str, filename: str) -> str:
     return dump
 
 
-@click.command()
+@click.command(help="Parse a Python or Midas file and pretty-print its AST")
 @click.argument("file", type=click.File("r"))
 @click.option("--raw", is_flag=True)
 def parse(file: TextIO, raw: bool):
diff --git a/midas/cli/commands/registry.py b/midas/cli/commands/registry.py
index 502be75..4e830be 100644
--- a/midas/cli/commands/registry.py
+++ b/midas/cli/commands/registry.py
@@ -12,7 +12,7 @@ from midas.checker.checker import TypeChecker
 from midas.checker.types import Type
 
 
-@click.command()
+@click.command(help="Dump types registry")
 @click.option("-t", "--types", type=click.File("r"), multiple=True)
 def dump_registry(
     types: tuple[TextIO],
diff --git a/midas/cli/commands/types.py b/midas/cli/commands/types.py
index 439611d..d17a0a8 100644
--- a/midas/cli/commands/types.py
+++ b/midas/cli/commands/types.py
@@ -14,7 +14,7 @@ from midas.cli.highlighter import DiagnosticsHighlighter
 from midas.cli.utils import DiagnosticPrinter
 
 
-@click.command()
+@click.command(help="Print typing judgements")
 @click.argument("file", type=click.File("r"))
 @click.option("-t", "--types", type=click.File("r"), multiple=True)
 @click.option("-l", "--highlight", type=click.File("w"))
diff --git a/midas/cli/commands/validate.py b/midas/cli/commands/validate.py
index 44e33bb..931c3e5 100644
--- a/midas/cli/commands/validate.py
+++ b/midas/cli/commands/validate.py
@@ -14,7 +14,7 @@ from midas.cli.highlighter import DiagnosticsHighlighter
 from midas.cli.utils import DiagnosticPrinter
 
 
-@click.command()
+@click.command(help="Validate Midas definitions")
 @click.argument("file", type=click.File("r"))
 @click.option("-l", "--highlight", type=click.File("w"))
 def validate(
diff --git a/midas/cli/highlighter.py b/midas/cli/highlighter.py
index ce63d62..1303f94 100644
--- a/midas/cli/highlighter.py
+++ b/midas/cli/highlighter.py
@@ -191,6 +191,13 @@ class PythonHighlighter(
     def visit_pass(self, stmt: p.Pass) -> None:
         pass
 
+    def visit_for_stmt(self, stmt: p.ForStmt) -> None:
+        self.wrap(stmt, "for")
+        stmt.iterator.accept(self)
+        stmt.target.accept(self)
+        for body_stmt in stmt.body:
+            body_stmt.accept(self)
+
     def visit_binary_expr(self, expr: p.BinaryExpr) -> None: ...
 
     def visit_compare_expr(self, expr: p.CompareExpr) -> None: ...
diff --git a/midas/generator/generator.py b/midas/generator/generator.py
index ceabdd5..bef6e16 100644
--- a/midas/generator/generator.py
+++ b/midas/generator/generator.py
@@ -161,5 +161,13 @@ class Generator(p.Stmt.Visitor[ast.stmt], p.Expr.Visitor[ast.expr]):
     def visit_pass(self, stmt: p.Pass) -> ast.stmt:
         return ast.Pass()
 
+    def visit_for_stmt(self, stmt: p.ForStmt) -> ast.stmt:
+        return ast.For(
+            target=stmt.target.accept(self),
+            iter=stmt.iterator.accept(self),
+            body=self._visit_body(stmt.body),
+            orelse=[],
+        )
+
     def _visit_body(self, stmts: list[p.Stmt]) -> list[ast.stmt]:
         return [stmt.accept(self) for stmt in stmts]
diff --git a/midas/parser/python.py b/midas/parser/python.py
index a0726da..55edd34 100644
--- a/midas/parser/python.py
+++ b/midas/parser/python.py
@@ -12,6 +12,7 @@ from midas.ast.python import (
     ConstraintType,
     Expr,
     ExpressionStmt,
+    ForStmt,
     FrameColumn,
     FrameType,
     Function,
@@ -93,6 +94,9 @@ class PythonParser:
             case ast.Pass():
                 return None
 
+            case ast.For(orelse=[]):
+                return self.parse_for(node)
+
             case _:
                 print(f"Unsupported statement: {ast.unparse(node)}")
                 return None
@@ -182,6 +186,22 @@ class PythonParser:
             orelse=orelse,
         )
 
+    def parse_for(self, node: ast.For) -> ForStmt:
+        body: list[Stmt] = []
+        for stmt in node.body:
+            stmts = self.parse_stmt(stmt)
+            if isinstance(stmts, Stmt):
+                body.append(stmts)
+            elif stmts is not None:
+                body.extend(stmts)
+
+        return ForStmt(
+            location=Location.from_ast(node),
+            target=self.parse_expr(node.target),
+            iterator=self.parse_expr(node.iter),
+            body=body,
+        )
+
     def parse_function(self, node: ast.FunctionDef) -> Function:
         loc: Location = Location.from_ast(node)
         match node:
diff --git a/tests/serializer/python.py b/tests/serializer/python.py
index e1f3fd4..56171b8 100644
--- a/tests/serializer/python.py
+++ b/tests/serializer/python.py
@@ -11,6 +11,7 @@ from midas.ast.python import (
     ConstraintType,
     Expr,
     ExpressionStmt,
+    ForStmt,
     FrameColumn,
     FrameType,
     Function,
@@ -182,6 +183,14 @@ class PythonAstJsonSerializer(
             "_type": "Pass",
         }
 
+    def visit_for_stmt(self, stmt: ForStmt) -> dict:
+        return {
+            "_type": "ForStmt",
+            "target": stmt.target.accept(self),
+            "iterator": stmt.iterator.accept(self),
+            "body": self._serialize_list(stmt.body),
+        }
+
     def visit_binary_expr(self, expr: BinaryExpr) -> dict:
         return {
             "_type": "BinaryExpr",