xo-expression: + Lambda::type_str

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"