[WIP] Move MXNet related files to mx namespace

src/gluonnlp/__init__.py

@@ -1,14 +1,5 @@
 __version__ = '1.0.0.dev'
 from . import base
 from . import data
-from . import models
-from . import utils
-from . import attention_cell
-from . import initializer as init
-from . import layers
-from . import loss
-from . import lr_scheduler
-from . import op
-from . import torch
-from . import sequence_sampler
 from . import embedding
+from . import utils

src/gluonnlp/data/__init__.py

@@ -3,4 +3,4 @@
 from . import batchify
 from .vocab import *
 
-__all__ = ['batchify', 'tokenizers'] + vocab.__all__
+__all__ = ['batchify', 'tokenizers', 'vocab'] + vocab.__all__

src/gluonnlp/mx/__init__.py

@@ -0,0 +1,17 @@
+from ..utils.lazy_imports import try_import_mxnet
+try_import_mxnet()
+
+
+from . import data
+from . import models
+from . import utils
+from . import attention_cell
+from . import initializer as init
+from . import layers
+from . import loss
+from . import lr_scheduler
+from . import op
+from . import sequence_sampler
+
+__all__ = ['data', ' models', 'utils', 'attention_cell',
+           'init', 'layers', 'loss', 'lr_scheduler', 'op', 'sequence_sampler']

src/gluonnlp/mx/data/__init__.py

@@ -0,0 +1,4 @@
+from . import batchify
+from . import loading
+
+__all__ = ['batchify', 'loading']

src/gluonnlp/torch/__init__.py

@@ -1,4 +1,9 @@
+from ..utils.lazy_imports import try_import_torch
+try_import_torch()
+
 from . import attention_cell
 from . import layers
 from . import models
 from . import utils
+
+__all__ = ['attention_cell', 'layers', 'models', 'utils']

src/gluonnlp/utils/lazy_imports.py

@@ -27,7 +27,9 @@
            'try_import_boto3',
            'try_import_jieba',
            'try_import_tvm',
-           'try_import_wikiextractor']
+           'try_import_wikiextractor',
+           'try_import_torch',
+           'try_import_mxnet']
 
 
 def try_import_sentencepiece():
@@ -180,3 +182,19 @@ def try_import_wikiextractor():
                           'refer to the official guide in '
                           'https://github.com/attardi/wikiextractor.')
     return wikiextractor
+
+
+def try_import_torch():
+    try:
+        import torch
+    except ImportError:
+        raise ImportError('PyTorch is not installed. You may install PyTorch by referring to the '
+                          'official guide in https://pytorch.org/.')
+
+
+def try_import_mxnet():
+    try:
+        import mxnet
+    except ImportError:
+        raise ImportError('MXNet is not installed. You may install MXNet by referring to the '
+                          'official guide in https://mxnet.apache.org/.')