Make vectors callable to get values by index (#933)

Fixes #932

Author: chrisrink10

CHANGELOG.md

@@ -21,6 +21,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  * Fix a bug where the compiler would emit warnings on when a Var was redef'ed even if that Var was initially defined with `^:redef` metadata (#916)
  * Fix a bug where reader column offset numbering began at 1, rather than 0 (#905)
  * Fix a bug where `basilisp.core/boolean` was returning the boolean coercions like Python rather than like Basilisp (#928)
+ * Fix a bug where Basilisp vectors were not callable (#932)
 
 ### Other
  * Add several sections to Concepts documentation module (#666)

src/basilisp/lang/compiler/analyzer.py

@@ -2433,7 +2433,7 @@ def _import_ast(form: ISeq, ctx: AnalyzerContext) -> Import:
                 raise ctx.AnalyzerException(
                     "import alias must take the form: [module :as alias]", form=f
                 )
-            module_name = f.val_at(0)
+            module_name = f.val_at(0)  # type: ignore[assignment]
             if not isinstance(module_name, sym.Symbol):
                 raise ctx.AnalyzerException(
                     "Python module name must be a symbol", form=f
@@ -2975,7 +2975,7 @@ def _require_ast(form: ISeq, ctx: AnalyzerContext) -> Require:
                 raise ctx.AnalyzerException(
                     "require alias must take the form: [namespace :as alias]", form=f
                 )
-            module_name = f.val_at(0)
+            module_name = f.val_at(0)  # type: ignore[assignment]
             if not isinstance(module_name, sym.Symbol):
                 raise ctx.AnalyzerException(
                     "Basilisp namespace name must be a symbol", form=f

src/basilisp/lang/vector.py

@@ -123,6 +123,9 @@ def __iter__(self):
     def __len__(self):
         return len(self._inner)
 
+    def __call__(self, k: int, default: Optional[T] = None) -> Optional[T]:
+        return self.val_at(k, default=default)
+
     def __lt__(self, other):
         """Return true if the `self` vector is shorter than the
         `other` vector, or the first unequal element in `self` when
@@ -165,16 +168,16 @@ def cons(self, *elems: T) -> "PersistentVector[T]":  # type: ignore[override]
     def assoc(self, *kvs: T) -> "PersistentVector[T]":
         return PersistentVector(self._inner.mset(*kvs))  # type: ignore[arg-type]
 
-    def contains(self, k):
+    def contains(self, k: int) -> bool:
         return 0 <= k < len(self._inner)
 
-    def entry(self, k):
+    def entry(self, k: int) -> Optional[IMapEntry[int, T]]:
         try:
             return MapEntry.of(k, self._inner[k])
         except IndexError:
             return None
 
-    def val_at(self, k, default=None):
+    def val_at(self, k: int, default: Optional[T] = None) -> Optional[T]:
         try:
             return self._inner[k]
         except IndexError:

tests/basilisp/vector_test.py

@@ -101,6 +101,16 @@ def test_entry():
     assert None is vec.PersistentVector.empty().entry(-1)
 
 
+def test_vector_callable():
+    assert "a" == vec.v("a")(0)
+    assert "b" == vec.v("a", "b")(1)
+    assert None is vec.v("a", "b")(2)
+    assert "b" == vec.v("a", "b")(-1)
+    assert None is vec.PersistentVector.empty()(0)
+    assert None is vec.PersistentVector.empty()(1)
+    assert None is vec.PersistentVector.empty()(-1)
+
+
 def test_val_at():
     assert "a" == vec.v("a").val_at(0)
     assert "b" == vec.v("a", "b").val_at(1)