Add more syntatic sugar

docs/api/python/index.rst

@@ -37,6 +37,7 @@ Python API
    relay/transform
    relay/analysis
    relay/backend
+   relay/dataflow_pattern
    relay/testing
    autotvm
    rpc

docs/langref/relay_pattern.rst

@@ -114,7 +114,7 @@ Since there are not call nodes, we need to use specific pattern nodes to match t
         x = relay.var('x')
         y = relay.var('y')
         z = relay.var('z')
-        tuple_pattern = TuplePattern((wildcard(), wildcard(), wildcard()))
+        tuple_pattern = is_tuple((wildcard(), wildcard(), wildcard()))
         assert tuple_pattern.match(relay.expr.Tuple((x,y,z)))
 
 The next example is matching a pattern of batch_norm -> get(0) -> relu:
@@ -123,7 +123,7 @@ The next example is matching a pattern of batch_norm -> get(0) -> relu:
 
     def test_match_tuple_get_item():
         bn_node = is_op('nn.batch_norm')(wildcard(), wildcard(), wildcard(), wildcard(), wildcard())
-        tuple_get_item_node = TupleGetItemPattern(bn_node, 0)
+        tuple_get_item_node = is_tuple_get_item(bn_node, 0)
         pat = is_op('nn.relu')(tuple_get_item_node)
 
         x = relay.var('x', shape=(1, 8))
@@ -142,7 +142,7 @@ if a specific parameter in a subgraph has been bound or not.
 .. code-block:: python
 
     def test_match_constant():
-        conv2d = is_op('nn.conv2d')(wildcard(), ConstantPattern())
+        conv2d = is_op('nn.conv2d')(wildcard(), is_constant())
         pattern = is_op('nn.bias_add')(conv2d, wildcard())
 
         x = relay.var('x', shape=(1, 3, 224, 224))
@@ -162,12 +162,12 @@ if a specific parameter in a subgraph has been bound or not.
         assert pattern.match(mod['main'].body)
 
 On the other hand, if you need to match the constant with a specific value, you can directly
-use ``ExprPattern``. This could be useful for algebraic simplify.
+use ``is_expr``. This could be useful for algebraic simplify.
 
 .. code-block:: python
 
     def test_match_plus_zero():
-        zero = (ExprPattern(relay.const(0)) | ExprPattern(relay.const(0.0)))
+        zero = (is_expr(relay.const(0)) | is_expr(relay.const(0.0)))
         pattern = wildcard() + zero
         
         x = relay.Var('x')
@@ -193,7 +193,7 @@ The next example is matching a diamond with two inputs at the top of the diamond
 
     def test_match_diamond():
         # Pattern
-        is_conv2d = is_op('nn.conv2d')(is_input(), is_input())
+        is_conv2d = is_op('nn.conv2d')(is_var(), is_var())
         path1 = is_op('nn.relu')(is_conv2d)
         path2 = is_op('nn.leaky_relu')(is_conv2d)
         diamond = is_op('add')(path1, path2)
@@ -213,7 +213,7 @@ The final example is matching diamonds with a post-dominator relationship. We em
 
     def test_match_dom_diamond():
         # Pattern
-        is_conv2d = is_op('nn.conv2d')(is_input(), is_input())
+        is_conv2d = is_op('nn.conv2d')(is_var(), is_var())
         reduction = is_op('add')(wildcard(), wildcard())
         diamond = dominates(is_conv2d, is_elemwise, reduction)
 
@@ -240,7 +240,12 @@ The high level design is to introduce a language of patterns for now we propose
             | pattern(pattern1, ... patternN)
             | has_type(pattern, type)
             | has_attr(pattern, attrs)
-            | is_input(name)
+            | is_var(name)
+            | is_constant()
+            | is_expr(expr)
+            | is_op(op_name)
+            | is_tuple()
+            | is_tuple_get_item()
             | pattern1 `|` pattern2
             | dominates(parent_pattern, path_pattern, child_pattern)