diff --git a/artiq/py2llvm/asttyped.py b/artiq/py2llvm/asttyped.py
new file mode 100644
index 000000000..21f3b07a1
--- /dev/null
+++ b/artiq/py2llvm/asttyped.py
@@ -0,0 +1,53 @@
+"""
+The typedtree module exports the PythonParser AST enriched with
+typing information.
+"""
+
+from pythonparser import ast
+from pythonparser.algorithm import Visitor as ASTVisitor
+
+class commontyped(ast.commonloc):
+    """A mixin for typed AST nodes."""
+
+    _types = ('type',)
+
+    def _reprfields(self):
+        return self._fields + self._locs + self._types
+
+class scoped(object):
+    """
+    :ivar typing_env: (dict with string keys and :class:`.types.Type` values)
+        map of variable names to variable types
+    :ivar globals_in_scope: (set of string keys)
+        list of variables resolved as globals
+    """
+
+class ClassDefT(ast.ClassDef, scoped):
+    pass
+
+class FunctionDefT(ast.FunctionDef, scoped):
+    pass
+
+class LambdaT(ast.Lambda, scoped):
+    pass
+
+class DictCompT(ast.DictComp, scoped):
+    pass
+
+class ListCompT(ast.ListComp, scoped):
+    pass
+
+class SetCompT(ast.SetComp, scoped):
+    pass
+
+class argT(ast.arg, commontyped):
+    pass
+
+class NumT(ast.Num, commontyped):
+    pass
+
+class NameT(ast.Name, commontyped):
+    pass
+
+class NameConstantT(ast.NameConstant, commontyped):
+    pass
diff --git a/artiq/py2llvm/types.py b/artiq/py2llvm/types.py
new file mode 100644
index 000000000..52cbe7518
--- /dev/null
+++ b/artiq/py2llvm/types.py
@@ -0,0 +1,189 @@
+"""
+The :mod:`types` module contains the classes describing the types
+in :mod:`asttyped`.
+"""
+
+import string
+
+def genalnum():
+    ident = ["a"]
+    while True:
+        yield "".join(ident)
+        pos = len(ident) - 1
+        while pos >= 0:
+            cur_n = string.ascii_lowercase.index(ident[pos])
+            if cur_n < 26:
+                ident[pos] = string.ascii_lowercase[cur_n + 1]
+                break
+            else:
+                ident[pos] = "a"
+                pos -= 1
+        if pos < 0:
+            ident = "a" + ident
+
+class UnificationError(Exception):
+    def __init__(self, typea, typeb):
+        self.typea, self.typeb = typea, typeb
+
+
+class Type(object):
+    pass
+
+class TVar(Type):
+    """
+    A type variable.
+
+    In effect, the classic union-find data structure is intrusively
+    folded into this class.
+    """
+
+    def __init__(self):
+        self.parent = self
+
+    def find(self):
+        if self.parent is self:
+            return self
+        else:
+            root = self.parent.find()
+            self.parent = root # path compression
+            return root
+
+    def unify(self, other):
+        other = other.find()
+
+        if self.parent is self:
+            self.parent = other
+        else:
+            self.find().unify(other)
+
+    def __repr__(self):
+        if self.parent is self:
+            return "TVar(%d)" % id(self)
+        else:
+            return repr(self.find())
+
+    # __eq__ and __hash__ are not overridden and default to
+    # comparison by identity. Use .find() explicitly before
+    # any lookups or comparisons.
+
+class TMono(Type):
+    """A monomorphic type, possibly parametric."""
+
+    def __init__(self, name, params={}):
+        self.name, self.params = name, params
+
+    def find(self):
+        return self
+
+    def unify(self, other):
+        if isinstance(other, TMono) and self.name == other.name:
+            assert self.params.keys() == other.params.keys()
+            for param in self.params:
+                self.params[param].unify(other.params[param])
+        else:
+            raise UnificationError(self, other)
+
+    def __repr__(self):
+        return "TMono(%s, %s)" % (repr(self.name), repr(self.params))
+
+    def __eq__(self, other):
+        return isinstance(other, TMono) and \
+                self.name == other.name and \
+                self.params == other.params
+
+    def __ne__(self, other):
+        return not (self == other)
+
+class TTuple(Type):
+    """A tuple type."""
+
+    def __init__(self, elts=[]):
+        self.elts = elts
+
+    def find(self):
+        return self
+
+    def unify(self, other):
+        if isinstance(other, TTuple) and len(self.elts) == len(other.elts):
+            for selfelt, otherelt in zip(self.elts, other.elts):
+                selfelt.unify(otherelt)
+        else:
+            raise UnificationError(self, other)
+
+    def __repr__(self):
+        return "TTuple(%s)" % (", ".join(map(repr, self.elts)))
+
+    def __eq__(self, other):
+        return isinstance(other, TTuple) and \
+                self.elts == other.elts
+
+    def __ne__(self, other):
+        return not (self == other)
+
+class TValue(Type):
+    """
+    A type-level value (such as the integer denoting width of
+    a generic integer type.
+    """
+
+    def __init__(self, value):
+        self.value = value
+
+    def find(self):
+        return self
+
+    def unify(self, other):
+        if self != other:
+            raise UnificationError(self, other)
+
+    def __repr__(self):
+        return "TValue(%s)" % repr(self.value)
+
+    def __eq__(self, other):
+        return isinstance(other, TValue) and \
+                self.value == other.value
+
+    def __ne__(self, other):
+        return not (self == other)
+
+def TBool():
+    """A boolean type."""
+    return TMono("bool")
+
+def TInt(width=TVar()):
+    """A generic integer type."""
+    return TMono("int", {"width": width})
+
+def TFloat():
+    """A double-precision floating point type."""
+    return TMono("float")
+
+
+class TypePrinter(object):
+    """
+    A class that prints types using Python-like syntax and gives
+    type variables sequential alphabetic names.
+    """
+
+    def __init__(self):
+        self.gen = genalnum()
+        self.map = {}
+
+    def name(self, typ):
+        typ = typ.find()
+        if isinstance(typ, TVar):
+            if typ not in self.map:
+                self.map[typ] = "'%s" % next(self.gen)
+            return self.map[typ]
+        elif isinstance(typ, TMono):
+            return "%s(%s)" % (typ.name, ", ".join(
+                ["%s=%s" % (k, self.name(typ.params[k])) for k in typ.params]))
+        elif isinstance(typ, TTuple):
+            if len(typ.elts) == 1:
+                return "(%s,)" % self.name(typ.elts[0])
+            else:
+                return "(%s)" % ", ".join(list(map(self.name, typ.elts)))
+        elif isinstance(typ, TValue):
+            return repr(typ.value)
+        else:
+            assert False
diff --git a/artiq/py2llvm/typing.py b/artiq/py2llvm/typing.py
new file mode 100644
index 000000000..effbca78f
--- /dev/null
+++ b/artiq/py2llvm/typing.py
@@ -0,0 +1,226 @@
+from pythonparser import source, ast, algorithm, diagnostic, parse_buffer
+from . import asttyped, types
+
+# This visitor will be called for every node with a scope,
+# i.e.: class, function, comprehension, lambda
+class LocalExtractor(algorithm.Visitor):
+    def __init__(self, engine):
+        super().__init__()
+        self.engine     = engine
+
+        self.in_root    = False
+        self.in_assign  = False
+        self.typing_env = {}
+
+        # which names are global have to be recorded in the current scope
+        self.global_    = set()
+
+        # which names are nonlocal only affects whether the current scope
+        # gets a new binding or not, so we throw this away
+        self.nonlocal_  = set()
+
+        # parameters can't be declared as global or nonlocal
+        self.params     = set()
+
+    def visit_in_assign(self, node):
+        try:
+            self.in_assign = True
+            return self.visit(node)
+        finally:
+            self.in_assign = False
+
+    def visit_Assign(self, node):
+        for target in node.targets:
+            self.visit_in_assign(target)
+        self.visit(node.value)
+
+    def visit_AugAssign(self, node):
+        self.visit_in_assign(node.target)
+        self.visit(node.op)
+        self.visit(node.value)
+
+    def visit_For(self, node):
+        self.visit_in_assign(node.target)
+        self.visit(node.iter)
+        self.visit(node.body)
+        self.visit(node.orelse)
+
+    def visit_withitem(self, node):
+        self.visit(node.context_expr)
+        if node.optional_vars is not None:
+            self.visit_in_assign(node.optional_vars)
+
+    def visit_comprehension(self, node):
+        self.visit_in_assign(node.target)
+        self.visit(node.iter)
+        for if_ in node.ifs:
+            self.visit(node.ifs)
+
+    def visit_root(self, node):
+        if self.in_root:
+            return
+        self.in_root = True
+        self.generic_visit(node)
+
+    visit_ClassDef    = visit_root # don't look at inner scopes
+    visit_FunctionDef = visit_root
+    visit_Lambda      = visit_root
+    visit_DictComp    = visit_root
+    visit_ListComp    = visit_root
+    visit_SetComp     = visit_root
+
+    def _assignable(self, name):
+        if name not in self.typing_env and name not in self.nonlocal_:
+            self.typing_env[name] = types.TVar()
+
+    def visit_arg(self, node):
+        self._assignable(node.arg)
+        self.params.add(node.arg)
+
+    def visit_Name(self, node):
+        if self.in_assign:
+            # code like:
+            # x = 1
+            # def f():
+            #   x = 1
+            # creates a new binding for x in f's scope
+            self._assignable(node.id)
+
+    def _check_not_in(self, name, names, curkind, newkind, loc):
+        if name in names:
+            diag = diagnostic.Diagnostic('fatal',
+                "name '{name}' cannot be {curkind} and {newkind} simultaneously",
+                {"name": name, "curkind": curkind, "newkind": newkind}, loc)
+            self.engine.process(diag)
+
+    def visit_Global(self, node):
+        for name, loc in zip(node.names, node.name_locs):
+            self._check_not_in(name, self.nonlocal_, 'nonlocal', 'global', loc)
+            self._check_not_in(name, self.params, 'a parameter', 'global', loc)
+            self.global_.add(name)
+
+    def visit_Nonlocal(self, node):
+        for name, loc in zip(node.names, node.name_locs):
+            self._check_not_in(name, self.global_, 'global', 'nonlocal', loc)
+            self._check_not_in(name, self.params, 'a parameter', 'nonlocal', loc)
+            self.nonlocal_.add(name)
+
+    def visit_ExceptHandler(self, node):
+        self.visit(node.type)
+        self._assignable(node.name)
+        for stmt in node.body:
+            self.visit(stmt)
+
+
+class Inferencer(algorithm.Transformer):
+    def __init__(self, engine):
+        self.engine = engine
+        self.env_stack = [{}]
+
+    def _unify(self, typea, typeb, loca, locb):
+        try:
+            typea.unify(typeb)
+        except types.UnificationError as e:
+            note1 = diagnostic.Diagnostic('note',
+                "expression of type {typea}",
+                {"typea": types.TypePrinter().name(typea)},
+                loca)
+            note2 = diagnostic.Diagnostic('note',
+                "expression of type {typeb}",
+                {"typeb": types.TypePrinter().name(typeb)},
+                locb)
+            diag = diagnostic.Diagnostic('fatal',
+                "cannot unify {typea} with {typeb}: {fraga} is incompatible with {fragb}",
+                {"typea": types.TypePrinter().name(typea),
+                 "typeb": types.TypePrinter().name(typeb),
+                 "fraga": types.TypePrinter().name(e.typea),
+                 "fragb": types.TypePrinter().name(e.typeb),},
+                loca, [locb], notes=[note1, note2])
+            self.engine.process(diag)
+
+    def visit_FunctionDef(self, node):
+        extractor = LocalExtractor(engine=self.engine)
+        extractor.visit(node)
+
+        self.env_stack.append(extractor.typing_env)
+        node = asttyped.FunctionDefT(
+            typing_env=extractor.typing_env, globals_in_scope=extractor.global_,
+            name=node.name, args=self.visit(node.args), returns=self.visit(node.returns),
+            body=[self.visit(x) for x in node.body], decorator_list=node.decorator_list,
+            keyword_loc=node.keyword_loc, name_loc=node.name_loc,
+            arrow_loc=node.arrow_loc, colon_loc=node.colon_loc, at_locs=node.at_locs,
+            loc=node.loc)
+        self.generic_visit(node)
+        self.env_stack.pop()
+
+        return node
+
+    def _find_name(self, name, loc):
+        for typing_env in reversed(self.env_stack):
+            if name in typing_env:
+                return typing_env[name]
+        diag = diagnostic.Diagnostic('fatal',
+            "name '{name}' is not bound to anything", {"name":name}, loc)
+        self.engine.process(diag)
+
+    def visit_arg(self, node):
+        return asttyped.argT(type=self._find_name(node.arg, node.loc),
+                             arg=node.arg, annotation=self.visit(node.annotation),
+                             arg_loc=node.arg_loc, colon_loc=node.colon_loc, loc=node.loc)
+
+    def visit_Num(self, node):
+        if isinstance(node.n, int):
+            typ = types.TInt()
+        elif isinstance(node.n, float):
+            typ = types.TFloat()
+        else:
+            diag = diagnostic.Diagnostic('fatal',
+                "numeric type {type} is not supported", node.n.__class__.__name__,
+                node.loc)
+            self.engine.process(diag)
+        return asttyped.NumT(type=typ,
+                             n=node.n, loc=node.loc)
+
+    def visit_Name(self, node):
+        return asttyped.NameT(type=self._find_name(node.id, node.loc),
+                              id=node.id, ctx=node.ctx, loc=node.loc)
+
+    def visit_Assign(self, node):
+        node = self.generic_visit(node)
+        if len(node.targets) > 1:
+            self._unify(types.TTuple([x.type for x in node.targets]), node.value.type,
+                        node.targets[0].loc.join(node.targets[-1].loc), node.value.loc)
+        else:
+            self._unify(node.targets[0].type, node.value.type,
+                        node.targets[0].loc, node.value.loc)
+        return node
+
+class Printer(algorithm.Visitor):
+    def __init__(self, buf):
+        self.rewriter = source.Rewriter(buf)
+        self.type_printer = types.TypePrinter()
+
+    def rewrite(self):
+        return self.rewriter.rewrite()
+
+    def generic_visit(self, node):
+        if hasattr(node, 'type'):
+            self.rewriter.insert_after(node.loc, " : %s" % self.type_printer.name(node.type))
+
+        super().generic_visit(node)
+
+def main():
+    import sys, fileinput
+    engine = diagnostic.Engine(all_errors_are_fatal=True)
+    try:
+        buf = source.Buffer("".join(fileinput.input()), fileinput.filename())
+        parsed = parse_buffer(buf, engine=engine)
+        typed = Inferencer(engine=engine).visit(parsed)
+        printer = Printer(buf)
+        printer.visit(typed)
+        print(printer.rewrite().source)
+    except diagnostic.Error as e:
+        print("\n".join(e.diagnostic.render()), file=sys.stderr)
+
+if __name__ == "__main__":
+    main()