From c6c05ab6335165140b91ae5ae6bd957d426e67da Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sun, 1 Feb 2026 00:16:37 -0500
Subject: [PATCH] xo-reader2: construct LambdaExpr to complete LambdaSsm +
 utest

---
 include/xo/expression2/StringTable.hpp |  5 +++++
 src/expression2/DLambdaExpr.cpp        | 12 +++++++++--
 src/expression2/DSequenceExpr.cpp      |  7 +++++-
 src/expression2/StringTable.cpp        | 30 ++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/include/xo/expression2/StringTable.hpp b/include/xo/expression2/StringTable.hpp
index 54b0a826..471fbc0d 100644
--- a/include/xo/expression2/StringTable.hpp
+++ b/include/xo/expression2/StringTable.hpp
@@ -35,6 +35,11 @@ namespace xo {
             /** return unique string with contents @p key. Idempotent! **/
             const DUniqueString * intern(std::string_view key);
 
+            /** generate unique symbol -- guaranteed not to collide
+             *  with existing symbol in this table.
+             **/
+            const DUniqueString * gensym(std::string_view prefix);
+
             /** verify StringTable invariants.
              *  Act on failure according to policy @p p
              **/
diff --git a/src/expression2/DLambdaExpr.cpp b/src/expression2/DLambdaExpr.cpp
index a27e788b..080e49b5 100644
--- a/src/expression2/DLambdaExpr.cpp
+++ b/src/expression2/DLambdaExpr.cpp
@@ -1,10 +1,12 @@
-/** @file DLambda.cpp
+/** @file DLambdaExpr.cpp
  *
  *  @author Roland Conybeare, Jan 2026
  **/
 
 #include "DLambdaExpr.hpp"
 #include "detail/IExpression_DLambdaExpr.hpp"
+#include "DLocalSymtab.hpp"
+#include "symtab/IPrintable_DLocalSymtab.hpp"
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/printable2/Printable.hpp>
 #include <xo/facet/FacetRegistry.hpp>
@@ -17,6 +19,7 @@ namespace xo {
     using xo::reflect::TypeDescrBase;
     using xo::reflect::FunctionTdxInfo;
     using xo::reflect::typeseq;
+    using xo::print::quot;
 
     namespace scm {
 
@@ -139,9 +142,14 @@ namespace xo {
                                                         AExpression>(body_expr_);
 
             if (name_ && body) {
+                auto local_symtab_pr
+                    = obj<APrintable,DLocalSymtab>(local_symtab_);
+
                 return ppii.pps()->pretty_struct(ppii,
                                                  "LambdaExpr",
-                                                 refrtag("name", name_),
+                                                 refrtag("tref", typeref_),
+                                                 refrtag("name", quot(std::string_view(*name_))),
+                                                 refrtag("local_symtab", local_symtab_pr),
                                                  //refrtag("argv", local_env_->argv()),
                                                  refrtag("body", body));
             } else {
diff --git a/src/expression2/DSequenceExpr.cpp b/src/expression2/DSequenceExpr.cpp
index 73b9c2b5..a9783802 100644
--- a/src/expression2/DSequenceExpr.cpp
+++ b/src/expression2/DSequenceExpr.cpp
@@ -6,6 +6,7 @@
 #include "DSequenceExpr.hpp"
 #include "detail/IExpression_DSequenceExpr.hpp"
 #include <xo/object2/array/IGCObject_DArray.hpp>
+#include <xo/object2/array/IPrintable_DArray.hpp>
 #include <xo/gc/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/printable2/Printable.hpp>
@@ -15,6 +16,7 @@
 
 namespace xo {
     using xo::mm::AGCObject;
+    using xo::print::APrintable;
     using xo::facet::FacetRegistry;
     using xo::reflect::typeseq;
 
@@ -95,9 +97,12 @@ namespace xo {
         {
             using xo::print::ppstate;
 
+            auto expr_v_pr = obj<APrintable,DArray>(expr_v_);
+
             return ppii.pps()->pretty_struct
                 (ppii,
-                 "DSequenceExpr");
+                 "DSequenceExpr",
+                 refrtag("expr_v", expr_v_pr));
         }
 
         // gc hooks for IGCObject_DSequenceExpr
diff --git a/src/expression2/StringTable.cpp b/src/expression2/StringTable.cpp
index ae48eea9..f59bb24d 100644
--- a/src/expression2/StringTable.cpp
+++ b/src/expression2/StringTable.cpp
@@ -72,6 +72,36 @@ namespace xo {
             return nullptr;
         }
 
+        const DUniqueString *
+        StringTable::gensym(std::string_view prefix)
+        {
+            static std::size_t s_counter = 0;
+
+            while (true) {
+                ++s_counter;
+
+                char buf[80];
+                assert(prefix.size() + 20 < sizeof(buf));
+
+                int n = snprintf(buf, sizeof(buf),
+                                 "%s:%lu",
+                                 prefix.data(), s_counter);
+
+                if ((0 < n) && (std::size_t(n) < sizeof(buf)))
+                    buf[n] = '\0';
+                else
+                    buf[sizeof(buf)-1] = '\0';
+
+                std::string_view sv(buf);
+                const DUniqueString * retval = this->lookup(sv);
+                if (!retval) {
+                    /* not already in string view -> we have viable candidate */
+                    retval = this->intern(sv);
+                    return retval;
+                }
+            }
+        }
+
         bool
         StringTable::verify_ok(verify_policy policy) const
         {