formal: extract from toplevel module.

The nMigen formal language is about to get *much* larger and will
keep growing faster than the rest of nMigen language, so it makes
good sense to extract it. Further, this makes it easier to qualify
formal keywords like `formal.AnyConst()` without directly importing
hdl.ast.

diff --git a/nmigen/__init__.py b/nmigen/__init__.py
index 473e8de6e82434ddf4f3f20f881db3b2eebeb655..88596a58c361f0595ee57d9fa1fbbddf9dc9d5c0 100644 (file)
--- a/nmigen/__init__.py
+++ b/nmigen/__init__.py
@@ -1,4 +1,4 @@
-from .hdl.ast import Value, Const, C, AnyConst, AnySeq, Mux, Cat, Repl, Array, Signal, ClockSignal, ResetSignal, Assert, Assume
+from .hdl.ast import Value, Const, C, Mux, Cat, Repl, Array, Signal, ClockSignal, ResetSignal
 from .hdl.dsl import Module
 from .hdl.cd import ClockDomain
 from .hdl.ir import Fragment, Instance

diff --git a/nmigen/formal.py b/nmigen/formal.py
new file mode 100644 (file)
index 0000000..3d97b33
--- /dev/null
+++ b/nmigen/formal.py
@@ -0,0 +1 @@
+from .hdl.ast import AnyConst, AnySeq, Assert, Assume