diff --git a/include/hobbes/lang/expr.H b/include/hobbes/lang/expr.H
index 8303f19c..bb96c989 100644
--- a/include/hobbes/lang/expr.H
+++ b/include/hobbes/lang/expr.H
@@ -19,6 +19,7 @@ public:
   virtual ~Expr();
 
   virtual void show(std::ostream&) const = 0;
+  [[nodiscard]] std::string toString() const;
   virtual void showAnnotated(std::ostream&) const = 0;
   virtual Expr* clone() const = 0;
   virtual bool operator==(const Expr&) const = 0;
diff --git a/include/hobbes/lang/module.H b/include/hobbes/lang/module.H
index 637f98be..6f984237 100644
--- a/include/hobbes/lang/module.H
+++ b/include/hobbes/lang/module.H
@@ -17,6 +17,7 @@ namespace hobbes {
 struct ModuleDef : public LexicallyAnnotated {
   virtual ~ModuleDef();
   virtual void show(std::ostream&) const = 0;
+  [[nodiscard]] std::string toString() const;
 
   // improves performance of case-analysis over instances (to avoid 'dynamic_cast')
 public:
@@ -243,6 +244,7 @@ public:
   const ModuleDefs&  definitions() const;
 
   void show(std::ostream& out) const;
+  [[nodiscard]] std::string toString() const;
 
   // allow language options set within modules
   void setOption(const std::string&, const LexicalAnnotation&);
diff --git a/include/hobbes/lang/preds/class.H b/include/hobbes/lang/preds/class.H
index 04ac66f0..8c51c3c1 100644
--- a/include/hobbes/lang/preds/class.H
+++ b/include/hobbes/lang/preds/class.H
@@ -68,6 +68,7 @@ public:
 
   // show this class definition
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
 public:
   const TCInstances& instances() const;
   bool hasGroundInstanceAt(const MonoTypes&) const;
@@ -122,6 +123,7 @@ public:
 
   // show this instance definition
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
 private:
   std::string   tcname;
   MonoTypes     itys;
@@ -152,6 +154,7 @@ public:
 
   // show this instance-generator definition
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
 
   // produce a sequence of type variables and constraints unique to this invocation
   using IFnDef = std::pair<Constraints, MonoTypes>;
diff --git a/include/hobbes/lang/type.H b/include/hobbes/lang/type.H
index 0db74564..42e571c9 100644
--- a/include/hobbes/lang/type.H
+++ b/include/hobbes/lang/type.H
@@ -41,6 +41,7 @@ public:
   using ptr = std::shared_ptr<MonoType>;
 
   virtual void show(std::ostream&) const = 0;
+  [[nodiscard]] std::string toString() const;
   bool operator==(const MonoType& rhs) const;
 
   // improves performance of case-analysis over instances (to avoid 'dynamic_cast')
@@ -109,6 +110,8 @@ public:
   // get access to the parent and root type environment from here
   const TEnvPtr& parentTypeEnv() const;
   TEnv* root();
+
+  [[nodiscard]] std::string toString() const;
 public:
   // get access to the internal type environment map (should only be used for debugging)
   using PolyTypeEnv = std::map<std::string, PolyTypePtr>;
@@ -179,6 +182,7 @@ public:
   QualTypePtr instantiate() const;
 
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
   bool operator==(const PolyType& rhs) const;
 
   // this should only be used if you don't mind capturing bound type variables
@@ -206,6 +210,7 @@ public:
   void monoType(const MonoTypePtr&);
 
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
   bool operator==(const QualType& rhs) const;
 private:
   Constraints cs;
@@ -238,6 +243,7 @@ public:
 
   // compare/show
   void show(std::ostream&) const;
+  [[nodiscard]] std::string toString() const;
   bool operator==(const Constraint& rhs) const;
 
   // are there free variables referenced in this constraint?
diff --git a/lib/hobbes/lang/expr.C b/lib/hobbes/lang/expr.C
index db3081eb..60156446 100644
--- a/lib/hobbes/lang/expr.C
+++ b/lib/hobbes/lang/expr.C
@@ -40,6 +40,11 @@ Expr::~Expr() = default;
 const QualTypePtr& Expr::type() const { return this->annotatedType; }
 void Expr::type(const QualTypePtr& ty) { this->annotatedType = ty; }
 int Expr::case_id() const { return this->cid; }
+std::string Expr::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 
 Primitive::Primitive(int cid, const LexicalAnnotation& la) : Expr(cid, la) { }
 bool PrimPtrLT::operator()(const PrimitivePtr& p0, const PrimitivePtr& p1) const { return *p0 < *p1; }
diff --git a/lib/hobbes/lang/module.C b/lib/hobbes/lang/module.C
index 8dd9f3a3..1d86cc2a 100644
--- a/lib/hobbes/lang/module.C
+++ b/lib/hobbes/lang/module.C
@@ -19,6 +19,11 @@ void Module::show(std::ostream& out) const {
     out << std::endl;
   }
 }
+std::string Module::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 
 bool isValidOption(const std::string& o) {
   return o == "Safe" || o == "SafeArrays" || o == "IgnoreUnreachableMatches";
@@ -39,6 +44,11 @@ const std::vector<std::string>& Module::options() const {
 /* module defs */
 ModuleDef::ModuleDef(int cid, const LexicalAnnotation& la) : LexicallyAnnotated(la), cid(cid) { }
 int ModuleDef::case_id() const { return this->cid; }
+std::string ModuleDef::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 ModuleDef::~ModuleDef() = default;
 
 // module imports
diff --git a/lib/hobbes/lang/preds/class.C b/lib/hobbes/lang/preds/class.C
index 30432782..ee761bd0 100644
--- a/lib/hobbes/lang/preds/class.C
+++ b/lib/hobbes/lang/preds/class.C
@@ -430,6 +430,11 @@ void TClass::show(std::ostream& out) const {
     out << "  " << tcmember.first << " :: " << hobbes::show(tcmember.second) << "\n";
   }
 }
+std::string TClass::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 
 const TCInstances& TClass::instances() const {
   return this->tcinstances;
@@ -519,6 +524,11 @@ void TCInstance::show(std::ostream& out) const {
     out << "  " << mm.first << " = " << hobbes::show(mm.second) << "\n";
   }
 }
+std::string TCInstance::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 
 ////////
 // generate class instances from class instance functions
@@ -757,6 +767,11 @@ void TCInstanceFn::show(std::ostream& out) const {
     out << "  " << mm.first << " = " << hobbes::show(substitute(simpl, mm.second)) << "\n";
   }
 }
+std::string TCInstanceFn::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 
 // generate a fresh type class and instance generator to control poly/qualtype instantiation in an expression
 void definePrivateClass(const TEnvPtr& tenv, const std::string& memberName, const ExprPtr& expr) {
diff --git a/lib/hobbes/lang/type.C b/lib/hobbes/lang/type.C
index 6d1c75da..3a0d0ef2 100644
--- a/lib/hobbes/lang/type.C
+++ b/lib/hobbes/lang/type.C
@@ -103,6 +103,14 @@ bool TEnv::hasImmediateBinding(const std::string& vname) const {
   return (this->ptenv.find(vname) != this->ptenv.end()) || (this->unquals && this->unquals->lookup(vname) != PolyTypePtr());
 }
 
+std::string TEnv::toString() const {
+  std::ostringstream out;
+  for (const auto& pe: ptenv) {
+    out << "    " << pe.first << ": " << pe.second->toString() << '\n';
+  }
+  return std::move(out).str();
+}
+
 void TEnv::bind(const std::string& vname, const PolyTypePtr& pt) {
   if (hasImmediateBinding(vname)) {
     throw std::runtime_error("Variable already defined: " + vname);
@@ -365,6 +373,12 @@ void PolyType::show(std::ostream& out) const {
   simplifyVarNames(instantiate())->show(out);
 }
 
+std::string PolyType::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
+
 bool PolyType::operator==(const PolyType& rhs) const {
   return this->vs == rhs.vs && *this->qt == *rhs.qt;
 }
@@ -406,7 +420,14 @@ void QualType::show(std::ostream& out) const {
   }
 }
 
+std::string QualType::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
+
 bool QualType::operator==(const QualType& rhs) const {
+
   return this->cs == rhs.cs && *this->mt == *rhs.mt;
 }
 
@@ -474,6 +495,12 @@ void Constraint::show(std::ostream& out) const {
   }
 }
 
+std::string Constraint::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
+
 bool Constraint::operator==(const Constraint& rhs) const {
   if (this->cat != rhs.cat || this->mts.size() != rhs.mts.size()) {
     return false;
@@ -492,6 +519,11 @@ bool Constraint::operator==(const Constraint& rhs) const {
 ////////
 MonoType::MonoType(int cid) : cid(cid), tgenCount(0), memorySize(-1) { }
 int MonoType::case_id() const { return this->cid; }
+std::string MonoType::toString() const {
+  std::ostringstream out;
+  this->show(out);
+  return std::move(out).str();
+}
 MonoType::~MonoType() = default;
 
 bool MonoType::operator==(const MonoType& rhs) const {