defreader: Allow strings as macro names

This makes it possible to use strings as the macro name argument to
defreader, which in turn makes it possible to define reader macros with
names that would otherwise result in parse errors.

Such as `#.`.

This fixes #918.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

hy/compiler.py

@@ -2456,7 +2456,7 @@ class HyASTCompiler(object):
         NOT_READERS = [":", "&"]
         if name in NOT_READERS or len(name) > 1:
             raise NameError("%s can't be used as a macro reader symbol" % name)
-        if not isinstance(name, HySymbol):
+        if not isinstance(name, HySymbol) and not isinstance(name, HyString):
             raise HyTypeError(name,
                               ("received a `%s' instead of a symbol "
                                "for reader macro name" % type(name).__name__))

tests/native_tests/reader_macros.hy

@@ -37,6 +37,15 @@
   (assert (= (, 1 2 3) a)))
 
 
+(defn test-reader-macro-string-name []
+  "Test if defreader accepts a string as a macro name."
+
+  (defreader "." [expr]
+    expr)
+
+  (assert (= #."works" "works")))
+
+
 (defn test-builtin-decorator-reader []
   (defn increment-arguments [func]
     "Increments each argument passed to the decorated function."