Create a basic exception type (#90)

Author: chrisrink10

basilisp/core/__init__.lpy

@@ -125,9 +125,16 @@
       (catch TypeError _
         (count (apply vector coll))))))
 
+(def
+  ^{:doc "Returns a basilisp.lang.exception/ExceptionInfo instance with
+          the given message and data."}
+  ex-info
+  (fn ex-info [msg data]
+    (basilisp.lang.exception/ExceptionInfo msg data)))
+
 (def
   ^{:macro true
-    :doc   ""}
+    :doc   "Define a new function."}
   defn
   (fn defn [&form name & body]
     (let [body (concat body)

basilisp/lang/exception.py

@@ -0,0 +1,25 @@
+import basilisp.lang.map as lmap
+from basilisp.lang.util import lrepr
+
+
+class ExceptionInfo(Exception):
+    __slots__ = ('_msg', '_data',)
+
+    def __init__(self, message: str, data: lmap.Map) -> None:
+        super().__init__()
+        self._msg = message
+        self._data = data
+
+    def __repr__(self):
+        return f"basilisp.lang.exception.ExceptionInfo({self._msg}, {lrepr(self._data)})"
+
+    def __str__(self):
+        return f"{self._msg} {lrepr(self._data)}"
+
+    @property
+    def data(self):
+        return self._data
+
+    @property
+    def message(self):
+        return self._data

basilisp/lang/runtime.py

@@ -177,6 +177,7 @@ class Namespace:
     - `imports` is a set of Python modules imported into the current
       namespace"""
     DEFAULT_IMPORTS = atom.Atom(pset(seq(['builtins',
+                                          'basilisp.lang.exception',
                                           'basilisp.lang.keyword',
                                           'basilisp.lang.list',
                                           'basilisp.lang.map',

tests/core_test.py

@@ -1,6 +1,10 @@
 from unittest.mock import Mock
 
+import pytest
+
+import basilisp.lang.map as lmap
 import basilisp.lang.runtime as runtime
+from basilisp.lang.exception import ExceptionInfo
 from basilisp.main import init
 
 init()
@@ -25,3 +29,8 @@ def teardown_module(module):
 
 def test_first():
     assert None is basilisp.core.first(None)
+
+
+def test_ex_info():
+    with pytest.raises(ExceptionInfo):
+        raise basilisp.core.ex_info("This is just an exception", lmap.m())