From 3ddf864e1b2c5c27b2e6f7203e262c85bf760f7c Mon Sep 17 00:00:00 2001
From: Ben Burdette <bburdette@protonmail.com>
Date: Fri, 4 Feb 2022 14:50:25 -0700
Subject: [PATCH] print value in break

---
 src/libcmd/command.cc  | 3 ++-
 src/libexpr/primops.cc | 6 +++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 5848a15bf..701976265 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -77,7 +77,8 @@ ref<EvalState> EvalCommand::getEvalState()
                 searchPath, getEvalStore(), getStore());
         if (startReplOnEvalErrors)
             debuggerHook = [evalState{ref<EvalState>(evalState)}](const Error * error, const Env & env, const Expr & expr) {
-                std::cout << "\033[2J\033[1;1H";
+                // clear the screen.
+                // std::cout << "\033[2J\033[1;1H";
               
                 if (error)
                     printError("%s\n\n" ANSI_BOLD "Starting REPL to allow you to inspect the current state of the evaluator.\n" ANSI_NORMAL, error->what());
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 3a54e1490..48a10cd27 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -712,12 +712,13 @@ static RegisterPrimOp primop_genericClosure(RegisterPrimOp::Info {
 
 static RegisterPrimOp primop_break({
     .name = "break",
-    .args = {},
+    .args = {"v"},
     .doc = R"(
       In debug mode, pause Nix expression evaluation and enter the repl.
     )",
     .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
     {
+        std::cout << "primop_break, value: " << *args[0] << std::endl;
         // PathSet context;
         // string s = state.coerceToString(pos, *args[0], context);
         if (debuggerHook && !state.debugTraces.empty())
@@ -728,6 +729,9 @@ static RegisterPrimOp primop_break({
           // const Env &env;
           // hintformat hint;
           debuggerHook(nullptr, dt.env, dt.expr);
+
+          // returning the value we were passed.
+          v = *args[0];
         }
     }
 });