chore: Added informative import errors

README.md

@@ -7,7 +7,7 @@
 <div align="center">
   <h2>
     <a href="https://pypi.org/project/vicinity/"><img src="https://img.shields.io/pypi/v/vicinity?color=%23007ec6&label=pypi%20package" alt="Package version"></a>
-    <a href="https://pypi.org/project/vicinity/"><img src="https://img.shields.io/pypi/pyversions/vicinity" alt="Supported Python versions"></a>
+    <a href="https://minish.ai/packages/vicinity/introduction"><img src="https://img.shields.io/badge/docs-minish.ai-blue.svg" alt="Docs"></a>
     <a href="https://pepy.tech/project/vicinity">
       <img src="https://static.pepy.tech/badge/vicinity" alt="Downloads">
     </a>

vicinity/backends/__init__.py

@@ -1,39 +1,64 @@
+from importlib.util import find_spec
 from typing import Union
 
 from vicinity.backends.base import AbstractBackend
 from vicinity.backends.basic import BasicBackend, BasicVectorStore
 from vicinity.datatypes import Backend
 
 
+class OptionalDependencyError(ImportError):
+    def __init__(self, backend: Backend, extra: str) -> None:
+        msg = f"{backend} requires extra '{extra}'.\n" f"Install it with: pip install 'vicinity[{extra}]'\n"
+        super().__init__(msg)
+        self.backend = backend
+        self.extra = extra
+
+
+def _require(module_name: str, backend: Backend, extra: str) -> None:
+    """Check if a dependency is importable, otherwise raise an error."""
+    if find_spec(module_name) is None:
+        raise OptionalDependencyError(backend, extra)
+
+
 def get_backend_class(backend: Union[Backend, str]) -> type[AbstractBackend]:
-    """Get all available backends."""
+    """Get the requested backend and ensure its dependencies are installed."""
     backend = Backend(backend)
+
     if backend == Backend.BASIC:
         return BasicBackend
+
     elif backend == Backend.HNSW:
+        _require("hnswlib", backend, "hnsw")
         from vicinity.backends.hnsw import HNSWBackend
 
         return HNSWBackend
+
     elif backend == Backend.ANNOY:
+        _require("annoy", backend, "annoy")
         from vicinity.backends.annoy import AnnoyBackend
 
         return AnnoyBackend
+
     elif backend == Backend.PYNNDESCENT:
+        _require("pynndescent", backend, "pynndescent")
         from vicinity.backends.pynndescent import PyNNDescentBackend
 
         return PyNNDescentBackend
 
     elif backend == Backend.FAISS:
+        _require("faiss", backend, "faiss")
         from vicinity.backends.faiss import FaissBackend
 
         return FaissBackend
 
     elif backend == Backend.USEARCH:
+        _require("usearch", backend, "usearch")
         from vicinity.backends.usearch import UsearchBackend
 
         return UsearchBackend
 
     elif backend == Backend.VOYAGER:
+        _require("voyager", backend, "voyager")
         from vicinity.backends.voyager import VoyagerBackend
 
         return VoyagerBackend

vicinity/version.py

@@ -1,2 +1,2 @@
-__version_triple__ = (0, 4, 2)
+__version_triple__ = (0, 4, 3)
 __version__ = ".".join(map(str, __version_triple__))