Thrift: OCaml library and generator

Summary: Added (minimal) library and code generator for OCaml.
Reviewed by: mcslee
Test plan: Test client and server (included).
Revert plan: yes


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665163 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/compiler/cpp/Makefile.am b/compiler/cpp/Makefile.am
index 98d0008..6465e56 100644
--- a/compiler/cpp/Makefile.am
+++ b/compiler/cpp/Makefile.am
@@ -15,8 +15,10 @@
                  src/generate/t_rb_generator.cc \
                  src/generate/t_xsd_generator.cc \
                  src/generate/t_perl_generator.cc \
+		 src/generate/t_ocaml_generator.cc \
                  src/generate/t_erl_generator.cc
 
+
 thrift_CXXFLAGS = -Wall -Isrc $(BOOST_CPPFLAGS)
 thrift_LDFLAGS = -Wall $(BOOST_LDFLAGS)
 
diff --git a/compiler/cpp/src/generate/t_generator.h b/compiler/cpp/src/generate/t_generator.h
index af1d4b1..52ffb70 100644
--- a/compiler/cpp/src/generate/t_generator.h
+++ b/compiler/cpp/src/generate/t_generator.h
@@ -118,6 +118,17 @@
   std::ostream& indent(std::ostream &os) {
     return os << indent();
   }
+  /**
+   * Capitalization helpers
+   */
+  std::string capitalize(std::string in) {
+    in[0] = toupper(in[0]);
+    return in;
+  }
+  std::string decapitalize(std::string in) {
+    in[0] = tolower(in[0]);
+    return in;
+  }
 
  protected:
   /**
diff --git a/compiler/cpp/src/generate/t_ocaml_generator.cc b/compiler/cpp/src/generate/t_ocaml_generator.cc
new file mode 100644
index 0000000..39ad45b
--- /dev/null
+++ b/compiler/cpp/src/generate/t_ocaml_generator.cc
@@ -0,0 +1,1520 @@
+// Copyright (c) 2006- Facebook
+// Distributed under the Thrift Software License
+//
+// See accompanying file LICENSE or visit the Thrift site at:
+// http://developers.facebook.com/thrift/
+
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sstream>
+#include "t_ocaml_generator.h"
+using namespace std;
+
+/*
+ * This is necessary because we want typedefs to appear later,
+ * after all the types have been declared.
+ */
+void t_ocaml_generator::generate_program() {
+  // Initialize the generator
+  init_generator();
+
+  // Generate enums
+  vector<t_enum*> enums = program_->get_enums();
+  vector<t_enum*>::iterator en_iter;
+  for (en_iter = enums.begin(); en_iter != enums.end(); ++en_iter) {
+    generate_enum(*en_iter);
+  }
+
+  // Generate structs
+  vector<t_struct*> structs = program_->get_structs();
+  vector<t_struct*>::iterator st_iter;
+  for (st_iter = structs.begin(); st_iter != structs.end(); ++st_iter) {
+    generate_struct(*st_iter);
+  }
+
+  // Generate xceptions
+  vector<t_struct*> xceptions = program_->get_xceptions();
+  vector<t_struct*>::iterator x_iter;
+  for (x_iter = xceptions.begin(); x_iter != xceptions.end(); ++x_iter) {
+    generate_xception(*x_iter);
+  }
+
+  // Generate typedefs
+  vector<t_typedef*> typedefs = program_->get_typedefs();
+  vector<t_typedef*>::iterator td_iter;
+  for (td_iter = typedefs.begin(); td_iter != typedefs.end(); ++td_iter) {
+    generate_typedef(*td_iter);
+  }
+
+  // Generate services
+  vector<t_service*> services = program_->get_services();
+  vector<t_service*>::iterator sv_iter;
+  for (sv_iter = services.begin(); sv_iter != services.end(); ++sv_iter) {
+    service_name_ = get_service_name(*sv_iter);
+    generate_service(*sv_iter);
+  }
+
+  // Generate constants
+  vector<t_const*> consts = program_->get_consts();
+  generate_consts(consts);
+
+  // Close the generator
+  close_generator();
+}
+
+
+/**
+ * Prepares for file generation by opening up the necessary file output
+ * streams.
+ *
+ * @param tprogram The program to generate
+ */
+void t_ocaml_generator::init_generator() {
+  // Make output directory
+  mkdir(T_OCAML_DIR, S_IREAD | S_IWRITE | S_IEXEC);
+
+  // Make output file
+  string f_types_name = string(T_OCAML_DIR)+"/"+program_name_+"_types.ml";
+  f_types_.open(f_types_name.c_str());
+  string f_types_i_name = string(T_OCAML_DIR)+"/"+program_name_+"_types.mli";
+  f_types_i_.open(f_types_i_name.c_str());
+
+  string f_consts_name = string(T_OCAML_DIR)+"/"+program_name_+"_consts.ml";
+  f_consts_.open(f_consts_name.c_str());
+
+  // Print header
+  f_types_ <<
+    ocaml_autogen_comment() << endl <<
+    ocaml_imports() << endl;
+  f_types_i_ <<
+    ocaml_autogen_comment() << endl <<
+    ocaml_imports() << endl;
+  f_consts_ <<
+    ocaml_autogen_comment() << endl <<
+    ocaml_imports() << endl <<
+    "open " << capitalize(program_name_)<<"_types"<< endl;
+}
+
+
+/**
+ * Autogen'd comment
+ */
+string t_ocaml_generator::ocaml_autogen_comment() {
+  return
+    std::string("(*\n") +
+    " Autogenerated by Thrift\n" +
+    "\n" +
+    " DO NOT EDIT UNLESS YOU ARE SURE YOU KNOW WHAT YOU ARE DOING\n" +
+    "*)\n";
+}
+
+/**
+ * Prints standard thrift imports
+ */
+string t_ocaml_generator::ocaml_imports() {
+  return "open Thrift";
+}
+
+/**
+ * Closes the type files
+ */
+void t_ocaml_generator::close_generator() {
+  // Close types file
+  f_types_.close();
+}
+ 
+/**
+ * Generates a typedef. Ez.
+ *
+ * @param ttypedef The type definition
+ */
+void t_ocaml_generator::generate_typedef(t_typedef* ttypedef) {
+  f_types_ <<
+    indent() << "type "<< decapitalize(ttypedef->get_symbolic()) << " = " << render_ocaml_type(ttypedef->get_type()) << endl << endl;
+  f_types_i_ <<
+    indent() << "type "<< decapitalize(ttypedef->get_symbolic()) << " = " << render_ocaml_type(ttypedef->get_type()) << endl << endl;
+}
+
+/**
+ * Generates code for an enumerated type. 
+ * the values.
+ *
+ * @param tenum The enumeration
+ */
+void t_ocaml_generator::generate_enum(t_enum* tenum) {
+  indent(f_types_) << "module " << capitalize(tenum->get_name()) << " = " << endl << "struct" << endl;
+  indent(f_types_i_) << "module " << capitalize(tenum->get_name()) << " : " << endl << "sig" << endl;
+  indent_up();
+  indent(f_types_) << "type t = " << endl;
+  indent(f_types_i_) << "type t = " << endl;
+  indent_up();
+  vector<t_enum_value*> constants = tenum->get_constants();
+  vector<t_enum_value*>::iterator c_iter;
+  int value = -1;
+  for (c_iter = constants.begin(); c_iter != constants.end(); ++c_iter) {
+    string name = capitalize((*c_iter)->get_name());
+    indent(f_types_) << "| " << name << endl;
+    indent(f_types_i_) << "| " << name << endl;
+  }
+  indent_down();
+
+  indent(f_types_) << "let to_i = function" << endl;
+  indent(f_types_i_) << "val to_i : t -> int" << endl;
+  indent_up();
+  for (c_iter = constants.begin(); c_iter != constants.end(); ++c_iter) {
+    if ((*c_iter)->has_value()) {
+      value = (*c_iter)->get_value();
+    } else {
+      ++value;
+    }
+    string name = capitalize((*c_iter)->get_name());
+    
+    f_types_ <<
+      indent() << "| " << name << " -> " << value << endl;
+  }
+  indent_down();
+
+  indent(f_types_) << "let of_i = function" << endl;
+  indent(f_types_i_) << "val of_i : int -> t" << endl;
+  indent_up();
+  for(c_iter = constants.begin(); c_iter != constants.end(); ++c_iter) {
+    if ((*c_iter)->has_value()) {
+      value = (*c_iter)->get_value();
+    } else {
+      ++value;
+    }
+    string name = capitalize((*c_iter)->get_name());
+    
+    f_types_ <<
+      indent() << "| " << value << " -> " << name << endl;
+  }
+  indent(f_types_) << "| _ -> raise Thrift_error" << endl;
+  indent_down();
+  indent_down();
+  indent(f_types_) << "end" << endl;
+  indent(f_types_i_) << "end" << endl;
+}
+
+/**
+ * Generate a constant value
+ */
+void t_ocaml_generator::generate_const(t_const* tconst) {
+  t_type* type = tconst->get_type();
+  string name = decapitalize(tconst->get_name());
+  t_const_value* value = tconst->get_value();
+
+  indent(f_consts_) << "let " << name << " = " << render_const_value(type, value) << endl << endl;
+}
+
+/**
+ * Prints the value of a constant with the given type. Note that type checking
+ * is NOT performed in this function as it is always run beforehand using the
+ * validate_types method in main.cc
+ */
+string t_ocaml_generator::render_const_value(t_type* type, t_const_value* value) {
+  std::ostringstream out;
+  if (type->is_base_type()) {
+    t_base_type::t_base tbase = ((t_base_type*)type)->get_base();
+    switch (tbase) {
+    case t_base_type::TYPE_STRING:
+      out << "\"" << value->get_string() << "\"";
+      break;
+    case t_base_type::TYPE_BOOL:
+      out << (value->get_integer() > 0 ? "true" : "false");
+      break;
+    case t_base_type::TYPE_BYTE:
+    case t_base_type::TYPE_I16:
+    case t_base_type::TYPE_I32:
+      out << value->get_integer();
+      break;
+    case t_base_type::TYPE_I64:
+      out << value->get_integer() << "L";
+      break;
+    case t_base_type::TYPE_DOUBLE:
+      if (value->get_type() == t_const_value::CV_INTEGER) {
+        out << value->get_integer();
+      } else {
+        out << value->get_double();
+      }
+      break;
+    default:
+      throw "compiler error: no const of base type " + tbase;
+    }
+  } else if (type->is_enum()) {
+    t_enum* tenum = (t_enum*)type;
+    vector<t_enum_value*> constants = tenum->get_constants();
+    vector<t_enum_value*>::iterator c_iter;
+    int val = -1;
+    for (c_iter = constants.begin(); c_iter != constants.end(); ++c_iter) {
+      if ((*c_iter)->has_value()) {
+        val = (*c_iter)->get_value();
+      } else {
+        ++val;
+      }
+      if(val == value->get_integer()){
+        indent(out) << capitalize(tenum->get_name()) << "." << capitalize((*c_iter)->get_name());
+        break;
+      }
+    }
+  } else if (type->is_struct() || type->is_xception()) {
+    string cname = type_name(type);
+    string ct = tmp("_c");
+    out << endl;
+    indent_up();
+    indent(out) << "(let " << ct << " = new " << cname << " in" << endl;
+    indent_up();
+    const vector<t_field*>& fields = ((t_struct*)type)->get_members();
+    vector<t_field*>::const_iterator f_iter;
+    const map<t_const_value*, t_const_value*>& val = value->get_map();
+    map<t_const_value*, t_const_value*>::const_iterator v_iter;
+    for (v_iter = val.begin(); v_iter != val.end(); ++v_iter) {
+      t_type* field_type = NULL;
+      for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+        if ((*f_iter)->get_name() == v_iter->first->get_string()) {
+          field_type = (*f_iter)->get_type();
+        }
+      }
+      if (field_type == NULL) {
+        throw "type error: " + type->get_name() + " has no field " + v_iter->first->get_string();
+      }
+      string fname = v_iter->first->get_string();
+      out << indent();
+      out << ct <<"#set_" << fname << " ";
+      out << render_const_value(field_type, v_iter->second);
+      out << ";" << endl;
+    }
+    indent(out) << ct << ")";
+    indent_down();
+    indent_down();
+  } else if (type->is_map()) {
+    t_type* ktype = ((t_map*)type)->get_key_type();
+    t_type* vtype = ((t_map*)type)->get_val_type();
+    const map<t_const_value*, t_const_value*>& val = value->get_map();
+    map<t_const_value*, t_const_value*>::const_iterator v_iter;
+    string hm = tmp("_hm");
+    out << endl;
+    indent_up();
+    indent(out) << "(let " << hm << " = Hashtbl.create " << val.size() << " in" << endl;
+    indent_up();
+    for (v_iter = val.begin(); v_iter != val.end(); ++v_iter) {
+      string key = render_const_value(ktype, v_iter->first);
+      string val = render_const_value(vtype, v_iter->second);
+      indent(out) << "Hashtbl.add " << hm << " " << key << " " << val << ";" << endl;
+    }
+    indent(out) << hm << ")";
+    indent_down();
+    indent_down();
+  } else if (type->is_list()) {
+    t_type* etype;
+    etype = ((t_list*)type)->get_elem_type();
+    out << "[" << endl;
+    indent_up();
+    const vector<t_const_value*>& val = value->get_list();
+    vector<t_const_value*>::const_iterator v_iter;
+    for (v_iter = val.begin(); v_iter != val.end(); ++v_iter) {
+      out << indent();
+      out << render_const_value(etype, *v_iter);
+      out << ";" << endl;
+    }
+    indent_down();
+    indent(out) << "]";
+  } else if (type->is_set()) {
+    t_type* etype = ((t_set*)type)->get_elem_type();
+    const vector<t_const_value*>& val = value->get_list();
+    vector<t_const_value*>::const_iterator v_iter;
+    string hm = tmp("_hm");
+    indent(out) << "(let " << hm << " = Hashtbl.create " << val.size() << " in" << endl;
+    indent_up();
+    for (v_iter = val.begin(); v_iter != val.end(); ++v_iter) {
+      string val = render_const_value(etype, *v_iter);
+      indent(out) << "Hashtbl.add " << hm << " " << val << " true;" << endl;
+    }
+    indent(out) << hm << ")" << endl;
+    indent_down();
+    out << endl;
+  }
+  return out.str();
+}
+
+/**
+ * Generates a "struct"
+ */
+void t_ocaml_generator::generate_struct(t_struct* tstruct) {
+  generate_ocaml_struct(tstruct, false);
+}
+
+/**
+ * Generates a struct definition for a thrift exception. Basically the same
+ * as a struct, but also has an exception declaration.
+ *
+ * @param txception The struct definition
+ */
+void t_ocaml_generator::generate_xception(t_struct* txception) {
+  generate_ocaml_struct(txception, true);  
+}
+
+/**
+ * Generates an OCaml struct
+ */
+void t_ocaml_generator::generate_ocaml_struct(t_struct* tstruct,
+                                              bool is_exception) {
+  generate_ocaml_struct_definition(f_types_, tstruct, is_exception);
+  generate_ocaml_struct_sig(f_types_i_,tstruct,is_exception);
+}
+
+/**
+ * Generates a struct definition for a thrift data type. 
+ *
+ * @param tstruct The struct definition
+ */
+void t_ocaml_generator::generate_ocaml_struct_definition(ofstream& out,
+                                                         t_struct* tstruct,
+                                                         bool is_exception) {
+  const vector<t_field*>& members = tstruct->get_members();
+  vector<t_field*>::const_iterator m_iter; 
+  string tname = type_name(tstruct);
+  indent(out) << "class " << tname << " =" << endl;
+  indent(out) << "object (self)" << endl;
+
+  indent_up();
+
+  string x = tmp("_x");
+  if (members.size() > 0) {
+    for (m_iter = members.begin(); m_iter != members.end(); ++m_iter) {
+      string mname = decapitalize((*m_iter)->get_name());
+      indent(out) << "val mutable _" << mname << " : " << render_ocaml_type((*m_iter)->get_type()) << " option = None" << endl;
+      indent(out) << "method get_" << mname << " = _" << mname << endl;
+      indent(out) << "method grab_" << mname << " = match _"<<mname<<" with None->raise (Field_empty \""<<tname<<"."<<mname<<"\") | Some " << x <<" -> " << x << endl;
+      indent(out) << "method set_" << mname << " " << x << " = _" << mname << " <- Some " << x << endl;
+    }
+  }
+  generate_ocaml_struct_writer(out, tstruct);
+  indent_down();
+  indent(out) << "end" << endl;
+
+  if(is_exception){
+    indent(out) << "exception " << capitalize(tname) <<" of " << tname << endl;
+  }
+
+  generate_ocaml_struct_reader(out, tstruct);
+}
+
+/**
+ * Generates a struct definition for a thrift data type. 
+ *
+ * @param tstruct The struct definition
+ */
+void t_ocaml_generator::generate_ocaml_struct_sig(ofstream& out,
+                                                  t_struct* tstruct,
+                                                  bool is_exception) {
+  const vector<t_field*>& members = tstruct->get_members();
+  vector<t_field*>::const_iterator m_iter; 
+  string tname = type_name(tstruct);
+  indent(out) << "class " << tname << " :" << endl;
+  indent(out) << "object" << endl;
+
+  indent_up();
+
+  string x = tmp("_x");
+  if (members.size() > 0) {
+    for (m_iter = members.begin(); m_iter != members.end(); ++m_iter) {
+      string mname = decapitalize((*m_iter)->get_name());
+      string type = render_ocaml_type((*m_iter)->get_type());
+      indent(out) << "method get_" << mname << " : " << type << " option" << endl;
+      indent(out) << "method grab_" << mname << " : " << type << endl;
+      indent(out) << "method set_" << mname << " : " << type << " -> unit" << endl;
+    }
+  }
+  indent(out) << "method write : Protocol.t -> unit" << endl;
+  indent_down();
+  indent(out) << "end" << endl;
+
+  if(is_exception){
+    indent(out) << "exception " << capitalize(tname) <<" of " << tname << endl;
+  }
+
+  indent(out) << "val read_" << tname << " : Protocol.t -> " << tname << endl;
+}
+
+/**
+ * Generates the read method for a struct
+ */
+void t_ocaml_generator::generate_ocaml_struct_reader(ofstream& out, t_struct* tstruct) {
+  const vector<t_field*>& fields = tstruct->get_members();
+  vector<t_field*>::const_iterator f_iter;
+  string sname = type_name(tstruct);
+  string str = tmp("_str");
+  string t = tmp("_t");
+  string id = tmp("_id");
+  indent(out) <<
+    "let rec read_" << sname << " (iprot : Protocol.t) =" << endl;
+  indent_up();
+  indent(out) << "let " << str << " = new " << sname << " in" << endl;
+  indent_up();
+  indent(out) <<
+    "ignore(iprot#readStructBegin);" << endl;   
+
+  // Loop over reading in fields
+  indent(out) <<
+    "(try while true do" << endl;
+  indent_up();
+  indent_up();
+    
+  // Read beginning field marker
+  indent(out) <<
+    "let (_," << t <<","<<id<<") = iprot#readFieldBegin in" << endl;
+  
+  // Check for field STOP marker and break
+  indent(out) <<
+    "if " << t <<" = Protocol.T_STOP then" << endl;
+  indent_up();
+  indent(out) <<
+      "raise Break" << endl;
+    indent_down();
+    indent(out) << "else ();" << endl;
+    
+    indent(out) << "(match " << id<<" with " << endl;
+    indent_up();
+    // Generate deserialization code for known cases
+    for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+      indent(out) << "| " << (*f_iter)->get_key() << " -> (";
+      out << "if " << t <<" = " << type_to_enum((*f_iter)->get_type()) << " then" << endl;
+      indent_up();
+      indent_up();
+      generate_deserialize_field(out, *f_iter,str);
+      indent_down();
+      out <<
+        indent() << "else" << endl <<
+        indent() << "  iprot#skip "<< t << ")" << endl;
+      indent_down();
+    }
+
+    // In the default case we skip the field
+    out <<
+      indent() << "| _ -> " << "iprot#skip "<<t<<");" << endl;
+    indent_down();      
+    // Read field end marker
+    indent(out) << "iprot#readFieldEnd;" << endl;
+    indent_down();
+    indent(out) << "done; ()" << endl;
+    indent_down();
+    indent(out) << "with Break -> ());" << endl;
+
+    indent(out) <<
+      "iprot#readStructEnd;" << endl;
+
+    indent(out) << str << endl << endl;
+    indent_down();
+    indent_down();
+}
+
+void t_ocaml_generator::generate_ocaml_struct_writer(ofstream& out,
+                                               t_struct* tstruct) {
+  string name = tstruct->get_name();
+  const vector<t_field*>& fields = tstruct->get_members();
+  vector<t_field*>::const_iterator f_iter;
+  string str = tmp("_str");
+  string f = tmp("_f");
+
+  indent(out) <<
+    "method write (oprot : Protocol.t) =" << endl;
+  indent_up();
+  indent(out) <<
+    "oprot#writeStructBegin \""<<name<<"\";" << endl;
+
+  for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+    // Write field header
+    string mname = "_"+decapitalize((*f_iter)->get_name());
+    indent(out) <<
+      "(match " << mname << " with None -> () | Some _v -> " << endl;
+    indent_up();
+    indent(out) << "oprot#writeFieldBegin(\""<< (*f_iter)->get_name()<<"\","
+                <<type_to_enum((*f_iter)->get_type())<<","
+                <<(*f_iter)->get_key()<<");" << endl;
+
+    // Write field contents
+    generate_serialize_field(out, *f_iter, "_v");
+
+    // Write field closer
+    indent(out) << "oprot#writeFieldEnd" << endl;
+
+    indent_down();
+    indent(out) << ");" << endl;
+  }
+
+  // Write the struct map
+  out <<
+    indent() << "oprot#writeFieldStop;" << endl <<
+    indent() << "oprot#writeStructEnd" << endl;
+
+  indent_down();
+}
+
+/**
+ * Generates a thrift service.
+ *
+ * @param tservice The service definition
+ */
+void t_ocaml_generator::generate_service(t_service* tservice) {
+  string f_service_name = string(T_OCAML_DIR)+"/"+capitalize(service_name_)+".ml";
+  f_service_.open(f_service_name.c_str());
+  string f_service_i_name = string(T_OCAML_DIR)+"/"+capitalize(service_name_)+".mli";
+  f_service_i_.open(f_service_i_name.c_str());
+
+  f_service_ <<
+    ocaml_autogen_comment() << endl <<
+    ocaml_imports() << endl;
+  f_service_i_ <<
+    ocaml_autogen_comment() << endl <<
+    ocaml_imports() << endl;
+
+  /* if (tservice->get_extends() != NULL) {
+    f_service_ <<
+      "open " << capitalize(tservice->get_extends()->get_name()) << endl;
+    f_service_i_ <<
+      "open " << capitalize(tservice->get_extends()->get_name()) << endl;
+  }
+  */
+  f_service_ <<
+     "open " << capitalize(program_name_) << "_types" << endl << 
+    endl;
+
+  f_service_i_ <<
+     "open " << capitalize(program_name_) << "_types" << endl << 
+    endl;
+
+  // Generate the three main parts of the service 
+  generate_service_helpers(tservice);
+  generate_service_interface(tservice);
+  generate_service_client(tservice);
+  generate_service_server(tservice);
+
+
+  // Close service file
+  f_service_.close();
+  f_service_i_.close();
+}
+
+/**
+ * Generates helper functions for a service.
+ *
+ * @param tservice The service to generate a header definition for
+ */
+void t_ocaml_generator::generate_service_helpers(t_service* tservice) {
+  vector<t_function*> functions = tservice->get_functions();
+  vector<t_function*>::iterator f_iter;
+
+  indent(f_service_) <<
+    "(* HELPER FUNCTIONS AND STRUCTURES *)" << endl << endl;
+
+  for (f_iter = functions.begin(); f_iter != functions.end(); ++f_iter) {
+    t_struct* ts = (*f_iter)->get_arglist();
+    generate_ocaml_struct_definition(f_service_, ts, false);
+    generate_ocaml_function_helpers(*f_iter);
+  }
+}
+
+/**
+ * Generates a struct and helpers for a function.
+ *
+ * @param tfunction The function
+ */
+void t_ocaml_generator::generate_ocaml_function_helpers(t_function* tfunction) {
+  t_struct result(program_, decapitalize(tfunction->get_name()) + "_result");
+  t_field success(tfunction->get_returntype(), "success", 0);
+  if (!tfunction->get_returntype()->is_void()) {
+    result.append(&success);
+  }
+
+  t_struct* xs = tfunction->get_xceptions();
+  const vector<t_field*>& fields = xs->get_members();
+  vector<t_field*>::const_iterator f_iter;
+  for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+    result.append(*f_iter);
+  }
+  generate_ocaml_struct_definition(f_service_, &result, false);
+}
+
+/**
+ * Generates a service interface definition.
+ *
+ * @param tservice The service to generate a header definition for
+ */
+void t_ocaml_generator::generate_service_interface(t_service* tservice) {
+  f_service_ <<
+    indent() << "class virtual iface =" << endl << "object (self)" << endl;
+  f_service_i_ <<
+    indent() << "class virtual iface :" << endl << "object" << endl;
+
+  indent_up();
+
+  if (tservice->get_extends() != NULL) {
+    string extends = type_name(tservice->get_extends());
+    indent(f_service_) << "inherit " << extends << ".iface" << endl;
+    indent(f_service_i_) << "inherit " << extends << ".iface" << endl;
+  }
+
+  vector<t_function*> functions = tservice->get_functions();
+  vector<t_function*>::iterator f_iter; 
+  for (f_iter = functions.begin(); f_iter != functions.end(); ++f_iter) {
+    string ft = function_type(*f_iter,true,true);
+    f_service_ <<
+      indent() << "method virtual " << decapitalize((*f_iter)->get_name()) << " : " << ft  << endl;
+    f_service_i_ <<
+      indent() << "method virtual " << decapitalize((*f_iter)->get_name()) << " : " << ft << endl;
+  }
+  indent_down();
+  indent(f_service_) << "end" << endl << endl;
+  indent(f_service_i_) << "end" << endl << endl;
+}
+
+/**
+ * Generates a service client definition. Note that in OCaml, the client doesn't implement iface. This is because
+ * The client does not (and should not have to) deal with arguments being None.
+ *
+ * @param tservice The service to generate a server for.
+ */
+void t_ocaml_generator::generate_service_client(t_service* tservice) {
+  string extends = "";
+  indent(f_service_) <<
+    "class client (iprot : Protocol.t) (oprot : Protocol.t) =" << endl << "object (self)" << endl;
+  indent(f_service_i_) <<
+    "class client : Protocol.t -> Protocol.t -> " << endl << "object" << endl;
+  indent_up();
+
+
+  if (tservice->get_extends() != NULL) {
+    extends = type_name(tservice->get_extends());
+    indent(f_service_) << "inherit " << extends << ".client iprot oprot as super" << endl;
+    indent(f_service_i_) << "inherit " << extends << ".client" << endl;
+  }
+  indent(f_service_) << "val mutable seqid = 0" << endl;
+   
+
+  // Generate client method implementations
+  vector<t_function*> functions = tservice->get_functions();
+  vector<t_function*>::const_iterator f_iter;    
+  for (f_iter = functions.begin(); f_iter != functions.end(); ++f_iter) {
+    t_struct* arg_struct = (*f_iter)->get_arglist();
+    const vector<t_field*>& fields = arg_struct->get_members();
+    vector<t_field*>::const_iterator fld_iter;
+    string funname = (*f_iter)->get_name();
+
+    // Open function
+    indent(f_service_) <<
+      "method " << function_signature(*f_iter) << " = " << endl;
+    indent(f_service_i_) <<
+      "method " << decapitalize((*f_iter)->get_name()) << " : " << function_type(*f_iter,true,false) << endl;
+    indent_up();
+    indent(f_service_) <<
+      "self#send_" << funname;
+
+ 
+    for (fld_iter = fields.begin(); fld_iter != fields.end(); ++fld_iter) {
+      f_service_ << " " << decapitalize((*fld_iter)->get_name());
+    }
+    f_service_ << ";" << endl;
+    
+    if (!(*f_iter)->is_async()) {
+      f_service_ << indent();
+      f_service_ <<
+        "self#recv_" << funname << endl;
+    }
+    indent_down();
+    
+    indent(f_service_) <<
+      "method private send_" << function_signature(*f_iter) << " = " << endl;
+    indent_up();
+    
+    std::string argsname = decapitalize((*f_iter)->get_name() + "_args");
+    
+    // Serialize the request header
+    f_service_ <<
+      indent() << "oprot#writeMessageBegin (\"" << (*f_iter)->get_name() << "\", Protocol.CALL, seqid);" << endl;
+    
+    f_service_ <<
+      indent() << "let args = new " << argsname << " in" << endl;
+    indent_up();
+    
+    for (fld_iter = fields.begin(); fld_iter != fields.end(); ++fld_iter) {
+      f_service_ <<
+        indent() << "args#set_" << (*fld_iter)->get_name() << " " << (*fld_iter)->get_name() << ";" << endl;
+    }
+    
+    // Write to the stream
+    f_service_ <<
+      indent() << "args#write oprot;" << endl <<
+      indent() << "oprot#writeMessageEnd;" << endl <<
+      indent() << "oprot#getTransport#flush" << endl;  
+    
+    indent_down();
+    indent_down();
+
+    if (!(*f_iter)->is_async()) {
+      std::string resultname = decapitalize((*f_iter)->get_name() + "_result");
+      t_struct noargs(program_);
+      
+      t_function recv_function((*f_iter)->get_returntype(),
+                               string("recv_") + (*f_iter)->get_name(),
+                               &noargs);
+      // Open function
+      f_service_ <<
+        indent() << "method private " << function_signature(&recv_function) << " =" << endl;
+      indent_up();
+
+      // TODO(mcslee): Validate message reply here, seq ids etc.
+
+      f_service_ <<
+        indent() << "let (fname, mtype, rseqid) = iprot#readMessageBegin in" << endl;
+      indent_up();
+      f_service_ <<
+        indent() << "(if mtype = Protocol.EXCEPTION then" << endl <<
+        indent() << "  let x = Application_Exn.read iprot in" << endl;
+      indent_up();
+      f_service_ <<
+        indent() << "  raise (Application_Exn.E x)" << endl;
+      indent_down();
+      f_service_ <<
+        indent() << "else ());" << endl;
+      string res = "_";
+
+      t_struct* xs = (*f_iter)->get_xceptions();
+      const std::vector<t_field*>& xceptions = xs->get_members();
+
+      if (!(*f_iter)->get_returntype()->is_void() || xceptions.size() > 0) {
+        res = "result";
+      }
+      f_service_ <<
+        indent() << "let "<<res<<" = read_" << resultname << " iprot in" << endl;
+      indent_up();
+      f_service_ <<
+        indent() << "iprot#readMessageEnd;" << endl;
+
+      // Careful, only return _result if not a void function
+      if (!(*f_iter)->get_returntype()->is_void()) {
+        f_service_ <<
+          indent() << "match result#get_success with Some v -> v | None -> (" << endl;
+        indent_up();
+      }
+      
+      
+      vector<t_field*>::const_iterator x_iter;
+      for (x_iter = xceptions.begin(); x_iter != xceptions.end(); ++x_iter) {
+        f_service_ <<
+          indent() << "(match result#get_" << (*x_iter)->get_name() << " with None -> () | Some _v ->" << endl;
+        indent(f_service_) << "  raise (" << capitalize(type_name((*x_iter)->get_type())) << " _v));" << endl;
+      }
+      
+      // Careful, only return _result if not a void function
+      if ((*f_iter)->get_returntype()->is_void()) {
+        indent(f_service_) <<
+          "()" << endl;
+      } else {
+        f_service_ <<
+          indent() << "raise (Application_Exn.E (Application_Exn.create Application_Exn.MISSING_RESULT \"" << (*f_iter)->get_name() << " failed: unknown result\")))" << endl;
+        indent_down();
+      }     
+
+      // Close function
+      indent_down();
+      indent_down();
+      indent_down();
+    }
+  }
+
+  indent_down();
+  indent(f_service_) << "end" << endl << endl;
+  indent(f_service_i_) << "end" << endl << endl;
+}
+
+/**
+ * Generates a service server definition.
+ *
+ * @param tservice The service to generate a server for.
+ */
+void t_ocaml_generator::generate_service_server(t_service* tservice) {
+  // Generate the dispatch methods
+  vector<t_function*> functions = tservice->get_functions();
+  vector<t_function*>::iterator f_iter; 
+
+
+  // Generate the header portion
+  indent(f_service_) <<
+    "class processor (handler : iface) =" << endl << indent() << "object (self)" << endl;
+  indent(f_service_i_) <<
+    "class processor : iface ->" << endl << indent() << "object" << endl;
+  indent_up();
+
+  f_service_ <<
+     indent() << "inherit Processor.t" << endl <<
+    endl;
+  f_service_i_ <<
+     indent() << "inherit Processor.t" << endl <<
+    endl;
+  string extends = "";
+ 
+  if (tservice->get_extends() != NULL) {
+    extends = type_name(tservice->get_extends());
+    indent(f_service_) << "inherit " + extends + ".processor (handler :> " + extends + ".iface)" << endl;
+    indent(f_service_i_) << "inherit " + extends + ".processor" << endl;
+  }
+
+  if (extends.empty()) {
+    indent(f_service_) << "val processMap = Hashtbl.create " << functions.size() << endl;
+  }
+  indent(f_service_i_) << "val processMap : (string, int * Protocol.t * Protocol.t -> unit) Hashtbl.t" << endl;
+ 
+  // Generate the server implementation
+  indent(f_service_) <<
+    "method process iprot oprot =" << endl;
+  indent(f_service_i_) <<
+    "method process : Protocol.t -> Protocol.t -> bool" << endl;
+  indent_up();
+
+  f_service_ <<
+    indent() << "let (name, typ, seqid)  = iprot#readMessageBegin in" << endl;
+  indent_up();
+  // TODO(mcslee): validate message
+
+  // HOT: dictionary function lookup
+  f_service_ <<
+    indent() << "if Hashtbl.mem processMap name then" << endl <<
+    indent() << "  (Hashtbl.find processMap name) (seqid, iprot, oprot)" << endl <<
+    indent() << "else (" << endl <<
+    indent() << "  iprot#skip(Protocol.T_STRUCT);" << endl <<
+    indent() << "  iprot#readMessageEnd;" << endl <<
+    indent() << "  let x = Application_Exn.create Application_Exn.UNKNOWN_METHOD (\"Unknown function \"^name) in" << endl <<
+    indent() << "    oprot#writeMessageBegin(name, Protocol.EXCEPTION, seqid);" << endl <<
+    indent() << "    x#write oprot;" << endl <<
+    indent() << "    oprot#writeMessageEnd;" << endl <<
+    indent() << "    oprot#getTransport#flush" << endl <<
+    indent() << ");" << endl;
+
+  // Read end of args field, the T_STOP, and the struct close
+  f_service_ <<
+    indent() << "true" << endl;
+  indent_down();
+  indent_down();
+  // Generate the process subfunctions
+  for (f_iter = functions.begin(); f_iter != functions.end(); ++f_iter) {
+    generate_process_function(tservice, *f_iter);
+  }
+
+  indent(f_service_) << "initializer" << endl;
+  indent_up();
+  for (f_iter = functions.begin(); f_iter != functions.end(); ++f_iter) {
+    f_service_ <<
+      indent() << "Hashtbl.add processMap \"" << (*f_iter)->get_name() << "\" self#process_" << (*f_iter)->get_name() << ";" << endl;
+  } 
+  indent_down();
+
+  indent_down();
+  indent(f_service_) << "end" << endl << endl;
+  indent(f_service_i_) << "end" << endl << endl;
+}
+
+/**
+ * Generates a process function definition.
+ *
+ * @param tfunction The function to write a dispatcher for
+ */
+void t_ocaml_generator::generate_process_function(t_service* tservice,
+                                               t_function* tfunction) {
+  // Open function
+  indent(f_service_) <<
+    "method private process_" << tfunction->get_name() <<
+    " (seqid, iprot, oprot) =" << endl;
+  indent_up();
+
+  string argsname = decapitalize(tfunction->get_name()) + "_args";
+  string resultname = decapitalize(tfunction->get_name()) + "_result";
+
+  // Generate the function call
+  t_struct* arg_struct = tfunction->get_arglist();
+  const std::vector<t_field*>& fields = arg_struct->get_members();
+  vector<t_field*>::const_iterator f_iter;
+
+  string args = "args";
+  if(fields.size() == 0){
+    args="_";
+  }
+
+  f_service_ <<
+    indent() << "let "<<args<<" = read_" << argsname << " iprot in" << endl;
+  indent_up();
+  f_service_ <<
+    indent() << "iprot#readMessageEnd;" << endl;
+
+  t_struct* xs = tfunction->get_xceptions();
+  const std::vector<t_field*>& xceptions = xs->get_members();
+  vector<t_field*>::const_iterator x_iter;
+
+  // Declare result for non async function
+  if (!tfunction->is_async()) {
+    f_service_ <<
+      indent() << "let result = new " << resultname << " in" << endl;
+    indent_up();
+  }
+
+  // Try block for a function with exceptions
+  if (xceptions.size() > 0) {
+    f_service_ <<
+      indent() << "(try" << endl;
+    indent_up();
+  }
+ 
+
+
+ 
+  f_service_ << indent();
+  if (!tfunction->is_async() && !tfunction->get_returntype()->is_void()) {
+    f_service_ << "result#set_success ";
+  }
+  f_service_ <<
+    "(handler#" << tfunction->get_name();
+  for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+    f_service_ <<  " args#get_" << (*f_iter)->get_name();
+  }
+  f_service_ << ");" << endl;
+
+  
+  if (xceptions.size() > 0) {
+    indent_down();
+    indent(f_service_) << "with" <<endl;
+    indent_up();
+    for (x_iter = xceptions.begin(); x_iter != xceptions.end(); ++x_iter) {
+      f_service_ <<
+        indent() << "| " << capitalize(type_name((*x_iter)->get_type())) << " " << (*x_iter)->get_name() << " -> " << endl;
+      indent_up();
+      indent_up();
+      if(!tfunction->is_async()){
+           f_service_ <<
+             indent() << "result#set_" << (*x_iter)->get_name() << " " << (*x_iter)->get_name() << endl;
+      } else {
+        indent(f_service_) << "()";
+      }
+      indent_down();
+      indent_down();
+    }
+    indent_down();
+    f_service_ << indent() << ");" << endl;
+  }
+
+
+
+  // Shortcut out here for async functions
+  if (tfunction->is_async()) {
+    f_service_ <<
+      indent() << "()" << endl;
+    indent_down();
+    indent_down();
+    return;
+  }
+
+  f_service_ <<
+    indent() << "oprot#writeMessageBegin (\"" << tfunction->get_name() << "\", Protocol.REPLY, seqid);" << endl <<
+    indent() << "result#write oprot;" << endl <<
+    indent() << "oprot#writeMessageEnd;" << endl <<
+    indent() << "oprot#getTransport#flush" << endl;
+
+  // Close function
+  indent_down();
+  indent_down();
+  indent_down();
+}
+
+/**
+ * Deserializes a field of any type.
+ */
+void t_ocaml_generator::generate_deserialize_field(ofstream &out,
+                                                   t_field* tfield,
+                                                   string prefix){
+  t_type* type = tfield->get_type();
+
+
+  string name = decapitalize(tfield->get_name());
+  indent(out) << prefix << "#set_"<<name << " ";
+  generate_deserialize_type(out,type);
+  out << endl;
+}
+
+
+/**
+ * Deserializes a field of any type.
+ */
+void t_ocaml_generator::generate_deserialize_type(ofstream &out,
+                                                   t_type* type){
+  while (type->is_typedef()) {
+    type = ((t_typedef*)type)->get_type();
+  }
+
+  if (type->is_void()) {
+    throw "CANNOT GENERATE DESERIALIZE CODE FOR void TYPE";
+  }
+
+
+  if (type->is_struct() || type->is_xception()) {
+    generate_deserialize_struct(out,
+                                (t_struct*)type);
+  } else if (type->is_container()) {
+    generate_deserialize_container(out, type);
+  } else if (type->is_base_type()) {
+    out << "iprot#";
+    t_base_type::t_base tbase = ((t_base_type*)type)->get_base();
+    switch (tbase) {
+    case t_base_type::TYPE_VOID:
+      throw "compiler error: cannot serialize void field in a struct";
+      break;
+    case t_base_type::TYPE_STRING:        
+      out << "readString";
+      break;
+    case t_base_type::TYPE_BOOL:
+      out << "readBool";
+      break;
+    case t_base_type::TYPE_BYTE:
+      out << "readByte";
+      break;
+    case t_base_type::TYPE_I16:
+      out << "readI16";
+      break;
+    case t_base_type::TYPE_I32:
+      out << "readI32";
+      break;
+    case t_base_type::TYPE_I64:
+      out << "readI64";
+      break;
+    case t_base_type::TYPE_DOUBLE:
+      out << "readDouble";
+      break;
+    default:
+      throw "compiler error: no PHP name for base type " + tbase;
+    }
+  } else if (type->is_enum()) {
+    string ename = capitalize(type->get_name());
+    out << "(" <<ename << ".of_i iprot#readI32)";
+  } else {
+    printf("DO NOT KNOW HOW TO DESERIALIZE TYPE '%s'\n",
+           type->get_name().c_str());
+  }
+}
+  
+
+/**
+ * Generates an unserializer for a struct, calling read()
+ */
+void t_ocaml_generator::generate_deserialize_struct(ofstream &out,
+                                                  t_struct* tstruct) {
+  string name = decapitalize(tstruct->get_name());
+  out << "(read_" << name << " iprot)";
+
+}
+
+/**
+ * Serialize a container by writing out the header followed by
+ * data and then a footer.
+ */
+void t_ocaml_generator::generate_deserialize_container(ofstream &out,
+                                                    t_type* ttype) {
+  string size = tmp("_size");
+  string ktype = tmp("_ktype");
+  string vtype = tmp("_vtype");
+  string etype = tmp("_etype");
+  string con = tmp("_con");
+  
+  t_field fsize(g_type_i32, size);
+  t_field fktype(g_type_byte, ktype);
+  t_field fvtype(g_type_byte, vtype);
+  t_field fetype(g_type_byte, etype);
+
+  out << endl;
+  indent_up();
+  // Declare variables, read header
+  if (ttype->is_map()) {
+    indent(out) << "(let ("<<ktype<<","<<vtype<<","<<size<<") = iprot#readMapBegin in" << endl;
+    indent(out) << "let "<<con<<" = Hashtbl.create "<<size<<" in" << endl;
+    indent_up(); 
+    indent(out) << "for i = 1 to "<<size<<" do" <<endl;
+    indent_up();
+    indent(out) << "let _k = ";
+    generate_deserialize_type(out,((t_map*)ttype)->get_key_type());
+    out << " in" << endl;
+    indent(out) << "let _v = ";
+    generate_deserialize_type(out,((t_map*)ttype)->get_val_type());
+    out << " in" << endl;
+    indent_up();
+    indent(out) << "Hashtbl.add "<<con<< " _k _v" << endl;
+    indent_down();
+    indent_down();
+    indent(out) << "done; iprot#readMapEnd; "<<con<<")";
+    indent_down();
+  } else if (ttype->is_set()) {
+    indent(out) << "(let ("<<etype<<","<<size<<") = iprot#readSetBegin in" << endl;
+    indent(out) << "let "<<con<<" = Hashtbl.create "<<size<<" in" << endl;
+    indent_up(); 
+    indent(out) << "for i = 1 to "<<size<<" do" <<endl;
+    indent_up();
+    indent(out) << "Hashtbl.add "<<con<<" ";
+    generate_deserialize_type(out,((t_set*)ttype)->get_elem_type());
+    out << " true" << endl;
+    indent_down();
+    indent(out) << "done; iprot#readSetEnd; "<<con<<")";
+    indent_down();
+  } else if (ttype->is_list()) {
+    indent(out) << "(let ("<<etype<<","<<size<<") = iprot#readListBegin in" << endl;
+    indent_up();
+    indent(out) << "let "<<con<<" = (Array.to_list (Array.init "<<size<<" (fun _ -> "; 
+    generate_deserialize_type(out,((t_list*)ttype)->get_elem_type());
+    out << "))) in" << endl;
+    indent_up();
+    indent(out) << "iprot#readListEnd; "<<con<<")";
+    indent_down();
+    indent_down();
+  }
+  indent_down();
+}
+
+
+
+/**
+ * Serializes a field of any type.
+ *
+ * @param tfield The field to serialize
+ * @param prefix Name to prepend to field name
+ */
+void t_ocaml_generator::generate_serialize_field(ofstream &out,
+                                                 t_field* tfield,
+                                                 string name) {
+  t_type* type = tfield->get_type();
+  while (type->is_typedef()) {
+    type = ((t_typedef*)type)->get_type();
+  }
+
+  // Do nothing for void types
+  if (type->is_void()) {
+    throw "CANNOT GENERATE SERIALIZE CODE FOR void TYPE: " +
+      tfield->get_name();
+  }
+
+  if(name.length() == 0){
+    name = decapitalize(tfield->get_name());
+  }  
+
+  if (type->is_struct() || type->is_xception()) {
+    generate_serialize_struct(out,
+                              (t_struct*)type,
+                              name);
+  } else if (type->is_container()) {
+    generate_serialize_container(out,
+                                 type,
+                                 name);
+  } else if (type->is_base_type() || type->is_enum()) {
+
+
+    indent(out) <<
+      "oprot#";
+    
+    if (type->is_base_type()) {
+      t_base_type::t_base tbase = ((t_base_type*)type)->get_base();
+      switch (tbase) {
+      case t_base_type::TYPE_VOID:
+        throw
+          "compiler error: cannot serialize void field in a struct: " + name;
+        break;
+      case t_base_type::TYPE_STRING:
+        out << "writeString(" << name << ")";
+        break;
+      case t_base_type::TYPE_BOOL:
+        out << "writeBool(" << name << ")";
+       break;
+      case t_base_type::TYPE_BYTE:
+        out << "writeByte(" << name << ")";
+        break;
+      case t_base_type::TYPE_I16:
+        out << "writeI16(" << name << ")";
+        break;
+      case t_base_type::TYPE_I32:
+        out << "writeI32(" << name << ")";
+        break;
+      case t_base_type::TYPE_I64:
+        out << "writeI64(" << name << ")";
+        break;
+      case t_base_type::TYPE_DOUBLE:
+        out << "writeDouble(" << name << ")";
+        break;
+      default:
+        throw "compiler error: no ocaml name for base type " + tbase;
+      }
+    } else if (type->is_enum()) {
+      string ename = capitalize(type->get_name());
+      out << "writeI32("<<ename<<".to_i " << name << ")";
+    }
+    
+  } else {
+    printf("DO NOT KNOW HOW TO SERIALIZE FIELD '%s' TYPE '%s'\n",
+           tfield->get_name().c_str(),
+           type->get_name().c_str());
+  }
+  out << ";" << endl;
+}
+
+/**
+ * Serializes all the members of a struct.
+ *
+ * @param tstruct The struct to serialize
+ * @param prefix  String prefix to attach to all fields
+ */
+void t_ocaml_generator::generate_serialize_struct(ofstream &out,
+                                               t_struct* tstruct,
+                                               string prefix) {
+  indent(out) << prefix << "#write(oprot)";
+}
+
+void t_ocaml_generator::generate_serialize_container(ofstream &out,
+                                                  t_type* ttype,
+                                                  string prefix) {
+  if (ttype->is_map()) {
+    indent(out) << "oprot#writeMapBegin("<< type_to_enum(((t_map*)ttype)->get_key_type()) << ",";
+    out << type_to_enum(((t_map*)ttype)->get_val_type()) << ",";
+    out << "Hashtbl.length " << prefix << ");" << endl;
+  } else if (ttype->is_set()) {
+    indent(out) <<
+      "oprot#writeSetBegin(" << type_to_enum(((t_set*)ttype)->get_elem_type()) << ",";
+    out << "Hashtbl.length " << prefix << ");" << endl;
+  } else if (ttype->is_list()) {
+    indent(out) <<
+      "oprot#writeListBegin(" << type_to_enum(((t_list*)ttype)->get_elem_type()) << ",";
+    out << "List.length " << prefix << ");" << endl;
+  }
+
+  if (ttype->is_map()) {
+    string kiter = tmp("_kiter");
+    string viter = tmp("_viter");
+    indent(out) << "Hashtbl.iter (fun "<<kiter<<" -> fun " << viter << " -> " << endl;
+    indent_up();
+    generate_serialize_map_element(out, (t_map*)ttype, kiter, viter);
+    indent_down();
+    indent(out) << ") " << prefix << ";" << endl;
+  } else if (ttype->is_set()) {
+    string iter = tmp("_iter");
+    indent(out) << "Hashtbl.iter (fun "<<iter<<" -> fun _ -> ";
+    indent_up();
+    generate_serialize_set_element(out, (t_set*)ttype, iter);
+    indent_down();
+    indent(out) << ") " << prefix << ";" << endl;
+  } else if (ttype->is_list()) {
+    string iter = tmp("_iter");
+    indent(out) << "List.iter (fun "<<iter<<" -> ";
+    indent_up();
+    generate_serialize_list_element(out, (t_list*)ttype, iter);
+    indent_down();
+    indent(out) << ") " << prefix << ";" <<  endl;
+  }
+    
+  if (ttype->is_map()) {
+    indent(out) <<
+      "oprot#writeMapEnd";
+  } else if (ttype->is_set()) {
+    indent(out) <<
+      "oprot#writeSetEnd";
+  } else if (ttype->is_list()) {
+    indent(out) <<
+      "oprot#writeListEnd";
+  }
+}
+
+/**
+ * Serializes the members of a map.
+ *
+ */
+void t_ocaml_generator::generate_serialize_map_element(ofstream &out,
+                                                     t_map* tmap,
+                                                     string kiter,
+                                                     string viter) {
+  t_field kfield(tmap->get_key_type(), kiter);
+  generate_serialize_field(out, &kfield);
+
+  t_field vfield(tmap->get_val_type(), viter);
+  generate_serialize_field(out, &vfield);
+}
+
+/**
+ * Serializes the members of a set.
+ */
+void t_ocaml_generator::generate_serialize_set_element(ofstream &out,
+                                                     t_set* tset,
+                                                     string iter) {
+  t_field efield(tset->get_elem_type(), iter);
+  generate_serialize_field(out, &efield);
+}
+
+/**
+ * Serializes the members of a list.
+ */
+void t_ocaml_generator::generate_serialize_list_element(ofstream &out,
+                                                      t_list* tlist,
+                                                      string iter) {
+  t_field efield(tlist->get_elem_type(), iter);
+  generate_serialize_field(out, &efield);
+}
+
+
+
+/**
+ * Renders a function signature of the form 'name args'
+ *
+ * @param tfunction Function definition
+ * @return String of rendered function definition
+ */
+string t_ocaml_generator::function_signature(t_function* tfunction,
+                                           string prefix) {
+  return
+    prefix + decapitalize(tfunction->get_name()) +
+    " " +  argument_list(tfunction->get_arglist());
+}
+
+string t_ocaml_generator::function_type(t_function* tfunc, bool method, bool options){
+  string result="";
+  
+  const vector<t_field*>& fields = tfunc->get_arglist()->get_members();
+  vector<t_field*>::const_iterator f_iter;
+  for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+    result += render_ocaml_type((*f_iter)->get_type());
+    if(options)
+      result += " option";
+    result += " -> ";
+  }
+  if(fields.empty() && !method){
+    result += "unit -> ";
+  }
+  result += render_ocaml_type(tfunc->get_returntype());
+  return result;
+}
+
+/**
+ * Renders a field list
+ */
+string t_ocaml_generator::argument_list(t_struct* tstruct) {
+  string result = "";
+
+  const vector<t_field*>& fields = tstruct->get_members();
+  vector<t_field*>::const_iterator f_iter;
+  bool first = true;
+  for (f_iter = fields.begin(); f_iter != fields.end(); ++f_iter) {
+    if (first) {
+      first = false;
+    } else {
+      result += " ";
+    }
+    result += (*f_iter)->get_name();
+  }
+  return result;
+}
+
+string t_ocaml_generator::type_name(t_type* ttype) {
+  string prefix = "";
+  t_program* program = ttype->get_program();
+  if (program != NULL && program != program_) {
+    if (!ttype->is_service()) {
+      prefix = capitalize(program->get_name()) + "_types.";
+    }
+  }
+
+  string name = ttype->get_name();
+  if(ttype->is_service()){
+    name = capitalize(name);
+  } else {
+    name = decapitalize(name);
+  }
+  return prefix + name;
+}
+
+/**
+ * Converts the parse type to a Protocol.t_type enum
+ */
+string t_ocaml_generator::type_to_enum(t_type* type) {
+  while (type->is_typedef()) {
+    type = ((t_typedef*)type)->get_type();
+  }
+  
+  if (type->is_base_type()) {
+    t_base_type::t_base tbase = ((t_base_type*)type)->get_base();
+    switch (tbase) {
+    case t_base_type::TYPE_VOID:
+      return "Protocol.T_VOID";
+    case t_base_type::TYPE_STRING:
+      return "Protocol.T_STRING";
+    case t_base_type::TYPE_BOOL:
+      return "Protocol.T_BOOL";
+    case t_base_type::TYPE_BYTE:
+      return "Protocol.T_BYTE";
+    case t_base_type::TYPE_I16:
+      return "Protocol.T_I16";
+    case t_base_type::TYPE_I32:
+      return "Protocol.T_I32";
+    case t_base_type::TYPE_I64:
+      return "Protocol.T_I64";
+    case t_base_type::TYPE_DOUBLE:
+      return "Protocol.T_DOUBLE";
+    }
+  } else if (type->is_enum()) {
+    return "Protocol.T_I32";
+  } else if (type->is_struct() || type->is_xception()) {
+    return "Protocol.T_STRUCT";
+  } else if (type->is_map()) {
+    return "Protocol.T_MAP";
+  } else if (type->is_set()) {
+    return "Protocol.T_SET";
+  } else if (type->is_list()) {
+    return "Protocol.T_LIST";
+  }
+
+  throw "INVALID TYPE IN type_to_enum: " + type->get_name();
+}
+
+/**
+ * Converts the parse type to an ocaml type
+ */
+string t_ocaml_generator::render_ocaml_type(t_type* type) {
+  while (type->is_typedef()) {
+    type = ((t_typedef*)type)->get_type();
+  }
+  
+  if (type->is_base_type()) {
+    t_base_type::t_base tbase = ((t_base_type*)type)->get_base();
+    switch (tbase) {
+    case t_base_type::TYPE_VOID:
+      return "unit";
+    case t_base_type::TYPE_STRING:
+      return "string";
+    case t_base_type::TYPE_BOOL:
+      return "bool";
+    case t_base_type::TYPE_BYTE:
+      return "int";
+    case t_base_type::TYPE_I16:
+      return "int";
+    case t_base_type::TYPE_I32:
+      return "int";
+    case t_base_type::TYPE_I64:
+      return "Int64.t";
+    case t_base_type::TYPE_DOUBLE:
+      return "float";
+    }
+  } else if (type->is_enum()) {
+    return capitalize(((t_enum*)type)->get_name())+".t";
+  } else if (type->is_struct() || type->is_xception()) {
+    return type_name((t_struct*)type);
+  } else if (type->is_map()) {
+    t_type* ktype = ((t_map*)type)->get_key_type();
+    t_type* vtype = ((t_map*)type)->get_val_type();
+    return "("+render_ocaml_type(ktype)+","+render_ocaml_type(vtype)+") Hashtbl.t";
+  } else if (type->is_set()) {
+    t_type* etype = ((t_set*)type)->get_elem_type();
+    return "("+render_ocaml_type(etype)+",bool) Hashtbl.t";
+  } else if (type->is_list()) {
+    t_type* etype = ((t_list*)type)->get_elem_type();
+    return render_ocaml_type(etype)+" list";
+  }
+
+  throw "INVALID TYPE IN type_to_enum: " + type->get_name();
+}
diff --git a/compiler/cpp/src/generate/t_ocaml_generator.h b/compiler/cpp/src/generate/t_ocaml_generator.h
new file mode 100644
index 0000000..1ea9b2f
--- /dev/null
+++ b/compiler/cpp/src/generate/t_ocaml_generator.h
@@ -0,0 +1,148 @@
+// Copyright (c) 2006- Facebook
+// Distributed under the Thrift Software License
+//
+// See accompanying file LICENSE or visit the Thrift site at:
+// http://developers.facebook.com/thrift/
+
+#ifndef T_OCAML_GENERATOR_H
+#define T_OCAML_GENERATOR_H
+
+#include <string>
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+#include "t_oop_generator.h"
+
+#define T_OCAML_DIR "gen-ocaml"
+
+/**
+ * OCaml code generator.
+ *
+ * @author Iain Proctor <iproctor@facebook.com>
+ */
+class t_ocaml_generator : public t_oop_generator {
+ public:
+  t_ocaml_generator(t_program* program) :
+    t_oop_generator(program) {}
+
+  /**
+   * Init and close methods
+   */
+
+  void init_generator();
+  void close_generator();
+
+  /**
+   * Program-level generation functions
+   */
+  void generate_program  ();
+  void generate_typedef  (t_typedef*  ttypedef);
+  void generate_enum     (t_enum*     tenum);
+  void generate_const    (t_const*    tconst);
+  void generate_struct   (t_struct*   tstruct);
+  void generate_xception (t_struct*   txception);
+  void generate_service  (t_service*  tservice);
+
+  std::string render_const_value(t_type* type, t_const_value* value);
+
+  /**
+   * Struct generation code
+   */
+
+  void generate_ocaml_struct(t_struct* tstruct, bool is_exception);
+  void generate_ocaml_struct_definition(std::ofstream& out, t_struct* tstruct, bool is_xception=false);
+  void generate_ocaml_struct_sig(std::ofstream& out, t_struct* tstruct, bool is_exception);
+  void generate_ocaml_struct_reader(std::ofstream& out, t_struct* tstruct);
+  void generate_ocaml_struct_writer(std::ofstream& out, t_struct* tstruct);
+  void generate_ocaml_function_helpers(t_function* tfunction);
+
+  /**
+   * Service-level generation functions
+   */
+
+  void generate_service_helpers   (t_service*  tservice);
+  void generate_service_interface (t_service* tservice);
+  void generate_service_client    (t_service* tservice);
+  void generate_service_server    (t_service* tservice);
+  void generate_process_function  (t_service* tservice, t_function* tfunction);
+
+  /**
+   * Serialization constructs
+   */
+
+  void generate_deserialize_field        (std::ofstream &out,
+                                          t_field*    tfield,
+                                          std::string prefix);
+  
+  void generate_deserialize_struct       (std::ofstream &out,
+                                          t_struct*   tstruct);
+  
+  void generate_deserialize_container    (std::ofstream &out,
+                                          t_type*     ttype);
+  
+  void generate_deserialize_set_element  (std::ofstream &out,
+                                          t_set*      tset);
+
+
+  void generate_deserialize_list_element (std::ofstream &out,
+                                          t_list*     tlist,
+                                          std::string prefix="");
+  void generate_deserialize_type          (std::ofstream &out,
+                                           t_type* type);
+
+  void generate_serialize_field          (std::ofstream &out,
+                                          t_field*    tfield,
+                                          std::string name= "");
+
+  void generate_serialize_struct         (std::ofstream &out,
+                                          t_struct*   tstruct,
+                                          std::string prefix="");
+
+  void generate_serialize_container      (std::ofstream &out,
+                                          t_type*     ttype,
+                                          std::string prefix="");
+
+  void generate_serialize_map_element    (std::ofstream &out,
+                                          t_map*      tmap,
+                                          std::string kiter,
+                                          std::string viter);
+
+  void generate_serialize_set_element    (std::ofstream &out,
+                                          t_set*      tmap,
+                                          std::string iter);
+
+  void generate_serialize_list_element   (std::ofstream &out,
+                                          t_list*     tlist,
+                                          std::string iter);
+
+  /**
+   * Helper rendering functions
+   */
+
+  std::string ocaml_autogen_comment();
+  std::string ocaml_imports();
+  std::string type_name(t_type* ttype);
+  std::string function_signature(t_function* tfunction, std::string prefix="");
+  std::string function_type(t_function* tfunc, bool method=false, bool options = false);
+  std::string argument_list(t_struct* tstruct);
+  std::string type_to_enum(t_type* ttype);
+  std::string render_ocaml_type(t_type* type);
+
+
+ private:
+
+  /**
+   * File streams
+   */
+
+  std::ofstream f_types_;
+  std::ofstream f_consts_;
+  std::ofstream f_service_;
+
+  std::ofstream f_types_i_;
+  std::ofstream f_service_i_;
+
+};
+
+#endif
diff --git a/compiler/cpp/src/generate/t_rb_generator.h b/compiler/cpp/src/generate/t_rb_generator.h
index 61a1d30..0c7524f 100644
--- a/compiler/cpp/src/generate/t_rb_generator.h
+++ b/compiler/cpp/src/generate/t_rb_generator.h
@@ -136,10 +136,7 @@
   std::string argument_list(t_struct* tstruct);
   std::string type_to_enum(t_type* ttype);
 
-  std::string capitalize(std::string in) {
-    in[0] = toupper(in[0]);
-    return in;
-  }
+
   
   std::string ruby_namespace(t_program* p) {
     std::string ns = p->get_ruby_namespace();
diff --git a/compiler/cpp/src/main.cc b/compiler/cpp/src/main.cc
index 949558e..b2abb9b 100644
--- a/compiler/cpp/src/main.cc
+++ b/compiler/cpp/src/main.cc
@@ -35,6 +35,7 @@
 #include "generate/t_rb_generator.h"
 #include "generate/t_xsd_generator.h"
 #include "generate/t_perl_generator.h"
+#include "generate/t_ocaml_generator.h"
 #include "generate/t_erl_generator.h"
 
 using namespace std;
@@ -126,6 +127,7 @@
 bool gen_phpi = false;
 bool gen_rest = false;
 bool gen_perl = false;
+bool gen_ocaml = false;
 bool gen_erl = false;
 bool gen_recurse = false;
 
@@ -304,6 +306,7 @@
   fprintf(stderr, "  -rb         Generate Ruby output files\n");
   fprintf(stderr, "  -xsd        Generate XSD output files\n");
   fprintf(stderr, "  -perl       Generate Perl output files\n");
+  fprintf(stderr, "  -ocaml      Generate OCaml output files\n");
   fprintf(stderr, "  -erl        Generate Erlang output files\n");
   fprintf(stderr, "  -I dir      Add a directory to the list of directories \n");
   fprintf(stderr, "                searched for include directives\n");
@@ -567,6 +570,13 @@
       delete perl;
     }
 
+    if (gen_ocaml) {
+      pverbose("Generating OCaml\n");
+      t_ocaml_generator* ocaml = new t_ocaml_generator(program);
+      ocaml->generate_program();
+      delete ocaml;
+    }
+
     if (gen_erl) {
       pverbose("Generating Erlang\n");
       t_erl_generator* erl = new t_erl_generator(program);
@@ -574,6 +584,7 @@
       delete erl;
     }
 
+
   } catch (string s) {
     printf("Error: %s\n", s.c_str());
   } catch (const char* exc) {
@@ -638,6 +649,8 @@
         gen_xsd = true;
       } else if (strcmp(arg, "-perl") == 0) {
         gen_perl = true;
+      } else if (strcmp(arg, "-ocaml") == 0) {
+        gen_ocaml = true;
       } else if (strcmp(arg, "-erl") == 0) {
         gen_erl = true;
       } else if (strcmp(arg, "-I") == 0) {
@@ -660,7 +673,7 @@
   }
 
   // You gotta generate something!
-  if (!gen_cpp && !gen_java && !gen_php && !gen_phpi && !gen_py && !gen_rb && !gen_xsd && !gen_perl && !gen_erl) {
+  if (!gen_cpp && !gen_java && !gen_php && !gen_phpi && !gen_py && !gen_rb && !gen_xsd && !gen_perl && !gen_ocaml && !gen_erl) {
     fprintf(stderr, "!!! No output language(s) specified\n\n");
     usage();
   }