From d2add0a683db749808769fbe13f29d499395ca89 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sat, 26 Mar 2022 16:00:49 +0800
Subject: [PATCH] update NAC3, define option type

---
 artiq/coredevice/exceptions.py  |  3 ++-
 artiq/language/core.py          | 46 ++++++++++++++++++++++++++++++---
 artiq/language/embedding_map.py |  3 ++-
 flake.lock                      |  8 +++---
 4 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/artiq/coredevice/exceptions.py b/artiq/coredevice/exceptions.py
index 29d10e4e9..8afc444a7 100644
--- a/artiq/coredevice/exceptions.py
+++ b/artiq/coredevice/exceptions.py
@@ -1,6 +1,7 @@
-from artiq.language.core import nac3
+from artiq.language.core import nac3, UnwrapNoneError
 from builtins import ZeroDivisionError, ValueError, IndexError, RuntimeError, AssertionError
 
+
 @nac3
 class RTIOUnderflow(Exception):
     """Raised when the CPU or DMA core fails to submit a RTIO event early
diff --git a/artiq/language/core.py b/artiq/language/core.py
index 3cff29c15..0e66cdb54 100644
--- a/artiq/language/core.py
+++ b/artiq/language/core.py
@@ -6,7 +6,6 @@ from typing import Generic, TypeVar
 from functools import wraps
 from inspect import getfullargspec, getmodule
 from types import SimpleNamespace
-from typing import TypeVar
 from math import floor, ceil
 
 from artiq.language import import_cache
@@ -16,9 +15,10 @@ __all__ = [
     "Kernel", "KernelInvariant", "virtual",
     "round64", "floor64", "ceil64",
     "extern", "kernel", "portable", "nac3", "rpc",
+    "print_rpc",
+    "Option", "Some", "none", "UnwrapNoneError",
     "parallel", "sequential",
     "set_watchdog_factory", "watchdog", "TerminationRequested",
-    "print_rpc"
 ]
 
 
@@ -109,13 +109,51 @@ def rpc(arg=None, flags={}):
     return arg
 
 
-T = TypeVar('T')
-
 @rpc
 def print_rpc(a: T):
     print(a)
 
 
+@nac3
+class UnwrapNoneError(Exception):
+    """Raised when unwrapping a none Option."""
+    artiq_builtin = True
+
+class Option(Generic[T]):
+    _nac3_option: T
+
+    def __init__(self, v: T):
+        self._nac3_option = v
+
+    def is_none(self):
+        return self._nac3_option is None
+
+    def is_some(self):
+        return self._nac3_option is not None
+
+    def unwrap(self):
+        if self.is_none():
+            raise UnwrapNoneError()
+        return self._nac3_option
+
+    def __repr__(self) -> str:
+        if self.is_none():
+            return "none"
+        else:
+            return "Some({})".format(repr(self._nac3_option))
+
+    def __str__(self) -> str:
+        if self.is_none():
+            return "none"
+        else:
+            return "Some({})".format(str(self._nac3_option))
+
+def Some(v: T) -> Option[T]:
+    return Option(v)
+
+none = Option(None)
+
+
 @nac3
 class KernelContextManager:
     @kernel
diff --git a/artiq/language/embedding_map.py b/artiq/language/embedding_map.py
index 6c323e7a4..64a041a6f 100644
--- a/artiq/language/embedding_map.py
+++ b/artiq/language/embedding_map.py
@@ -23,7 +23,8 @@ class EmbeddingMap:
                                           "CacheError",
                                           "SPIError",
                                           "0:ZeroDivisionError",
-                                          "0:IndexError"])
+                                          "0:IndexError",
+                                          "0:UnwrapNoneError"])
 
     def preallocate_runtime_exception_names(self, names):
         for i, name in enumerate(names):
diff --git a/flake.lock b/flake.lock
index b89102281..b75e5f65e 100644
--- a/flake.lock
+++ b/flake.lock
@@ -45,11 +45,11 @@
         "nixpkgs": "nixpkgs"
       },
       "locked": {
-        "lastModified": 1648132215,
-        "narHash": "sha256-Sts6AGduDi4jsD6YSYR2bwHW35TByGgHAfVPrenrCxg=",
+        "lastModified": 1648280781,
+        "narHash": "sha256-HSelJSl7Q4LNI1cCApsUULidDCnRcXRocT+/e31iHL8=",
         "ref": "master",
-        "rev": "55db05fdbb2ee35a907d32de778887716f71f5fe",
-        "revCount": 680,
+        "rev": "1ad4b0227c87736beec62d94161291b7e27de6cc",
+        "revCount": 685,
         "type": "git",
         "url": "https://git.m-labs.hk/m-labs/nac3.git"
       },