feat: load_scalar as Figure 2.3

Author: agentwidip

tests/test_loader.py

@@ -1,23 +1,41 @@
 import pytest
 
-from discopy import closed, monoidal
-
-from widip.lang import Box, Ty, Id
+from widip.lang import Ty, Id
 from widip.loader import repl_read
 
-@pytest.mark.parametrize(["yaml_text", "expected_box"], [
+
+INPUT_ONLY_SCALAR = Id(Ty("some spaced scalar") >> Ty()).curry(1, left=True)
+TAG_AND_VALUE_SCALAR = Id(Ty("tagged") @ Ty("scalar") >> Ty())
+TAG_ONLY_SCALAR = Id(Ty("just_tag") >> Ty()).curry(1, left=False)
+EMPTY_SCALAR = Id(Ty() >> Ty())
+EMPTY_STREAM = Id(Ty())
+
+
+@pytest.mark.parametrize(["yaml_text", "expected"], [
     [
         "some spaced scalar",
-        Box("⌜−⌝", Ty("some spaced scalar"), Ty() >> Ty("some spaced scalar"))],
+        INPUT_ONLY_SCALAR,
+    ],
     [
         "!tagged scalar",
-        Box("tagged", Ty("scalar"), Ty("tagged") >> Ty("tagged"))],
+        TAG_AND_VALUE_SCALAR,
+    ],
     [
         "!just_tag",
-        Box("just_tag", Ty(""), Ty("just_tag") >> Ty("just_tag"))],
+        TAG_ONLY_SCALAR,
+    ],
+    [
+        "''",
+        EMPTY_SCALAR,
+    ],
     [
         "",
-        Id(Ty())],
+        EMPTY_STREAM,
+    ],
 ])
-def test_loader_encoding(yaml_text, expected_box):
-    assert repl_read(yaml_text) == expected_box
+def test_loader_encoding(yaml_text, expected):
+    assert repl_read(yaml_text) == expected
+
+
+def test_scalar_and_tag_only_are_different_programs():
+    assert repl_read("some spaced scalar") != repl_read("!just_tag")

widip/lang.py

@@ -1,25 +1,33 @@
-"""The Run language category"""
+"""The Run language category."""
 
-from discopy import closed, markov, monoidal, symmetric
+from discopy import closed, markov, symmetric
 from discopy.utils import factory
 
+
 class Box(
     closed.Box,
     markov.Box,
-    symmetric.Box
+    symmetric.Box,
 ):
     """"""
 
+
 @factory
-class Ty(
-    closed.Ty,
-):
+class Ty(closed.Ty):
     def __rshift__(self, other):
-        return self.factory(closed.Under(self, other))
+        return self.factory(closed.Under(other, self))
 
     def __lshift__(self, other):
         return self.factory(closed.Over(self, other))
 
+    @property
+    def base(self):
+        return self.inside[0].base if self.is_exp else None
+
+    @property
+    def exponent(self):
+        return self.inside[0].exponent if self.is_exp else None
+
 
 def Id(x=None):
     """Identity diagram over widip.lang.Ty (defaults to Ty())."""

widip/loader.py

@@ -47,21 +47,16 @@ def _incidences_to_diagram(node: HyperGraph, index):
 
 
 def load_scalar(node, index, tag):
+    """Figure 2.3: If g = {G}, then g ◦ (s × id) = {Gs} uses G but g ◦ (id × t) = {H} does not."""
     v = hif_node(node, index)["value"]
-    if tag and v:
-        return Box(tag, Ty(v), Ty(tag) >> Ty(tag))
-        return Box("run", Ty(tag) @ Ty(v), Ty(tag)).curry(left=False)
-    elif tag:
-        return Box(tag, Ty(v), Ty(tag) >> Ty(tag))
-        return Box("run", Ty(tag), Ty(tag)).curry(left=False)
-        return Box(tag, Ty(), Ty() << Ty(""))
-    elif v:
-        return Box("⌜−⌝", Ty(v), Ty() >> Ty(v))
-        return Box("⌜−⌝", Ty(v), Ty(tag)).curry(0, left=False)
-        return Box("⌜−⌝", Ty(v), Ty() << Ty(""))
-    else:
-        return Box("⌜−⌝", Ty(), Ty() >> Ty(v))
-        return Box("⌜−⌝", Ty(), Ty(tag)).curry(0, left=False)
+    X = Ty(tag) if tag else Ty()
+    A = Ty(v) if v else Ty()
+    # Differentiate parameter-only vs input-only scalar forms.
+    if X == Ty() and A != Ty():
+        return Id(A >> Ty()).curry(1, left=True)
+    if X != Ty() and A == Ty():
+        return Id(X >> Ty()).curry(1, left=False)
+    return Id(X @ A >> Ty())
 
 def load_mapping(node, index, tag):
     ob = Id()
@@ -96,7 +91,6 @@ def load_mapping(node, index, tag):
     if tag:
         ob = (ob @ exps >> Eval(exps >> bases))
         box = Box(tag, ob.cod, Ty(tag) >> Ty(tag))
-        # box = Box("run", Ty(tag) @ ob.cod, Ty(tag)).curry(left=False)
         ob = ob >> box
     return ob