From 4b9f928a906a424c3f8a8c425e9f3a895a4c5da8 Mon Sep 17 00:00:00 2001
From: Javier Sagredo <javier.sagredo@iohk.io>
Date: Thu, 7 May 2026 01:15:54 +0200
Subject: [PATCH] Show tyvars on class node labels
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Class nodes now read "BftCrypto c" / "Bar a b" instead of just the
class name, in both the classes view (Render.hs's classNodes) and
the instance-view ensureClassNode helpers. External classes — for
which we don't know the tyvars — still fall back to the bare name.

Edge labels (the positional substitution into a superclass's args)
keep using the *origin* class's tyvar names via edgeLabel, so an
arrow `Bar a b ──(b)──► Foo b` reads consistently — same letter on
edge and target node.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 data/viewer.js           | 13 +++++++++++--
 src/Classgraph/Render.hs | 13 ++++++++++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/data/viewer.js b/data/viewer.js
index f86a705..4e20c6d 100644
--- a/data/viewer.js
+++ b/data/viewer.js
@@ -533,9 +533,15 @@
       if (seenNodes.has(id)) return id;
       seenNodes.add(id);
       const known = classById.get(id);
+      // Include the class's tyvars in the label when we have them
+      // (i.e. the class is defined in this project). External classes
+      // fall back to bare qnName — we don't have their tyvars here.
+      const label = (known && known.ciTyVars && known.ciTyVars.length > 0)
+        ? known.ciName.qnName + ' ' + known.ciTyVars.map(tv => tv.tvName).join(' ')
+        : qn.qnName;
       els.push({ group: 'nodes', data: Object.assign({
         id,
-        label: qn.qnName,
+        label,
         kind: 'class',
         external: !known,
         package: qn.qnPackage,
@@ -981,9 +987,12 @@
       if (seenNodes.has(id)) return id;
       seenNodes.add(id);
       const known = classById.get(id);
+      const label = (known && known.ciTyVars && known.ciTyVars.length > 0)
+        ? known.ciName.qnName + ' ' + known.ciTyVars.map(tv => tv.tvName).join(' ')
+        : qn.qnName;
       els.push({ group: 'nodes', data: {
         id,
-        label: qn.qnName,
+        label,
         kind: 'class',
         external: !known,
         package: qn.qnPackage,
diff --git a/src/Classgraph/Render.hs b/src/Classgraph/Render.hs
index b6e9436..ff149bd 100644
--- a/src/Classgraph/Render.hs
+++ b/src/Classgraph/Render.hs
@@ -118,7 +118,7 @@ buildGraph pd sourceRoots = CyGraph
     classNodes =
       [ CyNode $ Aeson.object
           [ "id"      Aeson..= renderQualName (ciName c)
-          , "label"   Aeson..= qnName (ciName c)
+          , "label"   Aeson..= classNodeLabel c
           , "kind"    Aeson..= ("class" :: Text)
           , "module"  Aeson..= qnModule (ciName c)
           , "package" Aeson..= qnPackage (ciName c)
@@ -129,6 +129,17 @@ buildGraph pd sourceRoots = CyGraph
       | c <- pdClasses pd
       ]
 
+    -- A class node renders as `Foo a b c`, with the same names the
+    -- user wrote. Edge labels (positional substitution into a
+    -- superclass's args) keep using the *origin* class's tyvar names
+    -- via 'edgeLabel', so an arrow from `Bar a b` up to `Foo a` reads
+    -- as `(a)` on the edge and `Foo a` on the target node — same
+    -- letter, no aliasing.
+    classNodeLabel c = case ciTyVars c of
+      []  -> qnName (ciName c)
+      tvs -> qnName (ciName c) <> " "
+               <> T.intercalate " " (map tvName tvs)
+
     familyNodes =
       [ CyNode $ Aeson.object
           [ "id"      Aeson..= renderQualName (tfName f)
-- 
2.54.0