From 697e7d76c411d2321c27c6c6c0b993a488b6c6d0 Mon Sep 17 00:00:00 2001
From: Seyon Sivarajah <seyon.sivarajah@quantinuum.com>
Date: Mon, 4 Mar 2024 14:38:18 +0000
Subject: [PATCH] feat: don't include empty type args in Display (#857)

---
 .../snapshots/hugr__hugr__views__tests__dot_string.snap     | 2 +-
 src/types.rs                                                | 3 +--
 src/types/custom.rs                                         | 6 +++++-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/hugr/views/snapshots/hugr__hugr__views__tests__dot_string.snap b/src/hugr/views/snapshots/hugr__hugr__views__tests__dot_string.snap
index 6a166f9a3..2a04e5b4e 100644
--- a/src/hugr/views/snapshots/hugr__hugr__views__tests__dot_string.snap
+++ b/src/hugr/views/snapshots/hugr__hugr__views__tests__dot_string.snap
@@ -2,5 +2,5 @@
 source: src/hugr/views/tests.rs
 expression: h.dot_string()
 ---
-"digraph {\n0 [shape=plain label=<<table border=\"1\"><tr><td align=\"text\" border=\"0\" colspan=\"1\">(0) DFG</td></tr></table>>]\n1 [shape=plain label=<<table border=\"1\"><tr><td align=\"text\" border=\"0\" colspan=\"2\">(1) Input</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >0: qubit([])</td><td port=\"out1\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >1: qubit([])</td></tr></table>>]\n1:out0 -> 3:in0 [style=\"\"]\n1:out1 -> 3:in1 [style=\"\"]\n2 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >0: qubit([])</td><td port=\"in1\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >1: qubit([])</td></tr><tr><td align=\"text\" border=\"0\" colspan=\"2\">(2) Output</td></tr></table>>]\n3 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >0: qubit([])</td><td port=\"in1\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >1: qubit([])</td></tr><tr><td align=\"text\" border=\"0\" colspan=\"6\">(3) test.quantum.CX</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >0: qubit([])</td><td port=\"out1\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >1: qubit([])</td><td port=\"out2\" align=\"text\" colspan=\"2\" cellpadding=\"1\" border=\"0\"></td></tr></table>>]\n3:out0 -> 4:in1 [style=\"\"]\n3:out1 -> 4:in0 [style=\"\"]\n3:out2 -> 4:in2 [style=\"dotted\"]\n4 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >0: qubit([])</td><td port=\"in1\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >1: qubit([])</td><td port=\"in2\" align=\"text\" colspan=\"2\" cellpadding=\"1\" border=\"0\"></td></tr><tr><td align=\"text\" border=\"0\" colspan=\"6\">(4) test.quantum.CX</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >0: qubit([])</td><td port=\"out1\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >1: qubit([])</td></tr></table>>]\n4:out0 -> 2:in0 [style=\"\"]\n4:out1 -> 2:in1 [style=\"\"]\nhier0 [shape=plain label=\"0\"]\nhier0 -> hier1  [style = \"dashed\"] \nhier0 -> hier2  [style = \"dashed\"] \nhier0 -> hier3  [style = \"dashed\"] \nhier0 -> hier4  [style = \"dashed\"] \nhier1 [shape=plain label=\"1\"]\nhier2 [shape=plain label=\"2\"]\nhier3 [shape=plain label=\"3\"]\nhier4 [shape=plain label=\"4\"]\n}\n"
+"digraph {\n0 [shape=plain label=<<table border=\"1\"><tr><td align=\"text\" border=\"0\" colspan=\"1\">(0) DFG</td></tr></table>>]\n1 [shape=plain label=<<table border=\"1\"><tr><td align=\"text\" border=\"0\" colspan=\"2\">(1) Input</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >0: qubit</td><td port=\"out1\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >1: qubit</td></tr></table>>]\n1:out0 -> 3:in0 [style=\"\"]\n1:out1 -> 3:in1 [style=\"\"]\n2 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >0: qubit</td><td port=\"in1\" align=\"text\" colspan=\"1\" cellpadding=\"1\" >1: qubit</td></tr><tr><td align=\"text\" border=\"0\" colspan=\"2\">(2) Output</td></tr></table>>]\n3 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >0: qubit</td><td port=\"in1\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >1: qubit</td></tr><tr><td align=\"text\" border=\"0\" colspan=\"6\">(3) test.quantum.CX</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >0: qubit</td><td port=\"out1\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >1: qubit</td><td port=\"out2\" align=\"text\" colspan=\"2\" cellpadding=\"1\" border=\"0\"></td></tr></table>>]\n3:out0 -> 4:in1 [style=\"\"]\n3:out1 -> 4:in0 [style=\"\"]\n3:out2 -> 4:in2 [style=\"dotted\"]\n4 [shape=plain label=<<table border=\"1\"><tr><td port=\"in0\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >0: qubit</td><td port=\"in1\" align=\"text\" colspan=\"2\" cellpadding=\"1\" >1: qubit</td><td port=\"in2\" align=\"text\" colspan=\"2\" cellpadding=\"1\" border=\"0\"></td></tr><tr><td align=\"text\" border=\"0\" colspan=\"6\">(4) test.quantum.CX</td></tr><tr><td port=\"out0\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >0: qubit</td><td port=\"out1\" align=\"text\" colspan=\"3\" cellpadding=\"1\" >1: qubit</td></tr></table>>]\n4:out0 -> 2:in0 [style=\"\"]\n4:out1 -> 2:in1 [style=\"\"]\nhier0 [shape=plain label=\"0\"]\nhier0 -> hier1  [style = \"dashed\"] \nhier0 -> hier2  [style = \"dashed\"] \nhier0 -> hier3  [style = \"dashed\"] \nhier0 -> hier4  [style = \"dashed\"] \nhier1 [shape=plain label=\"1\"]\nhier2 [shape=plain label=\"2\"]\nhier3 [shape=plain label=\"3\"]\nhier4 [shape=plain label=\"4\"]\n}\n"
 
diff --git a/src/types.rs b/src/types.rs
index aaf616354..4cc5e895c 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -422,8 +422,7 @@ pub(crate) mod test {
         ]);
         assert_eq!(
             t.to_string(),
-            "Tuple([usize([]), Function(forall . [[]][]), my_custom([]), Alias(my_alias)])"
-                .to_string()
+            "Tuple([usize, Function(forall . [[]][]), my_custom, Alias(my_alias)])".to_string()
         );
     }
 
diff --git a/src/types/custom.rs b/src/types/custom.rs
index 2224b7325..50e112502 100644
--- a/src/types/custom.rs
+++ b/src/types/custom.rs
@@ -124,6 +124,10 @@ impl CustomType {
 
 impl Display for CustomType {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}({:?})", self.id, self.args)
+        if self.args.is_empty() {
+            write!(f, "{}", self.id)
+        } else {
+            write!(f, "{}({:?})", self.id, self.args)
+        }
     }
 }