feat(builders): expose resolve() and support custom deferred repr

koerce/builders.py

@@ -224,7 +224,9 @@ def __init__(self, value: Any):
             self.value = value
 
     def __repr__(self):
-        if callable(self.value):
+        if hasattr(self.value, "__deferred_repr__"):
+            return self.value.__deferred_repr__()
+        elif callable(self.value):
             return getattr(self.value, "__name__", repr(self.value))
         else:
             return repr(self.value)
@@ -767,6 +769,6 @@ def deferred(obj, allow_custom=False) -> Deferred:
     return Deferred(builder(obj, allow_custom))
 
 
-def resolve(obj, context):
+def resolve(obj, **context):
     bldr: Builder = builder(obj)
     return bldr.build(context)

koerce/patterns.py

@@ -1357,7 +1357,7 @@ class Custom(Pattern):
 
     """
 
-    func: Callable
+    func = cython.declare(object, visibility="readonly")
 
     def __init__(self, func):
         self.func = func

koerce/tests/test_builders.py

@@ -7,6 +7,7 @@
 from koerce._internal import (
     Attr,
     Binop,
+    Builder,
     Call,
     Call0,
     Call1,
@@ -18,11 +19,11 @@
     Item,
     Just,
     Map,
-    Builder,
     Seq,
     Unop,
     Var,
     builder,
+    resolve,
 )
 
 _ = Deferred(Var("_"))
@@ -349,6 +350,11 @@ def table():
     )
 
 
+def test_custom_deferred_repr(table):
+    expr = _.x + table.a
+    assert repr(expr) == "($_.x + <column[int]>)"
+
+
 def test_deferred_getitem(table):
     expr = _["a"]
     assert resolve(expr, table) == table["a"]
@@ -518,3 +524,8 @@ def test_builder_coercion():
     assert Builder.__coerce__(Var("a")) == Var("a")
     with pytest.raises(ValueError):
         Builder.__coerce__(1)
+
+
+def test_resolve():
+    deferred = _["a"] + 1
+    assert resolve(deferred, _={"a": 1}) == 2