From b18de1b0ce51288254a75615f98a50b6a3b1dfd4 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Mon, 17 Jun 2024 17:00:16 -0400
Subject: [PATCH] xo-expression: + Lambda::type_str

---
 include/xo/expression/Lambda.hpp |  8 ++++++--
 src/expression/Lambda.cpp        | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/include/xo/expression/Lambda.hpp b/include/xo/expression/Lambda.hpp
index 7f5ebab4..06d5857f 100644
--- a/include/xo/expression/Lambda.hpp
+++ b/include/xo/expression/Lambda.hpp
@@ -23,8 +23,7 @@ namespace xo {
              **/
             Lambda(const std::string & name,
                    const std::vector<std::string> & argv,
-                   const ref::rp<Expression> & body)
-                : Expression(exprtype::lambda), name_{name}, argv_{argv}, body_{body} {}
+                   const ref::rp<Expression> & body);
 
             /** downcast from Expression **/
             static ref::brw<Lambda> from(ref::brw<Expression> x) {
@@ -32,6 +31,7 @@ namespace xo {
             }
 
             const std::string & name() const { return name_; }
+            const std::string & type_str() const { return type_str_; }
             const std::vector<std::string> & argv() const { return argv_; }
             const ref::rp<Expression> & body() const { return body_; }
 
@@ -51,6 +51,10 @@ namespace xo {
              *  so that they can be linked etc.
              **/
             std::string name_;
+            /** e.g.
+             *    "double(double,double)"  for function of two doubles that returns a double
+             **/
+            std::string type_str_;
             /** formal argument names **/
             std::vector<std::string> argv_;
             /** function body **/
diff --git a/src/expression/Lambda.cpp b/src/expression/Lambda.cpp
index 87f70759..cae46f6f 100644
--- a/src/expression/Lambda.cpp
+++ b/src/expression/Lambda.cpp
@@ -4,7 +4,30 @@
 #include "xo/indentlog/print/vector.hpp"
 
 namespace xo {
+    using std::stringstream;
+
     namespace ast {
+        Lambda::Lambda(const std::string & name,
+                       const std::vector<std::string> & argv,
+                       const ref::rp<Expression> & body)
+            : Expression(exprtype::lambda),
+              name_{name},
+              argv_{argv},
+              body_{body}
+        {
+            stringstream ss;
+            ss << "double";
+            ss << "(";
+            for (std::size_t i = 0; i < argv.size(); ++i) {
+                if (i > 0)
+                    ss << ",";
+                ss << "double";
+            }
+            ss << ")";
+
+            type_str_ = ss.str();
+        } /*ctor*/
+
         void
         Lambda::display(std::ostream & os) const {
             os << "<Lambda"