#140 Support creating Java lambdas, export Idris functions as Java classes, constructors, fields and functions

[mmhelloworld]

• Support passing Idris functions as Java lambdas like:

Stream.fromCollection list >>=
            (flip map (\s => toPrim $ pure $ (s ++ " idris"))) >>=
            (flip filter (\s => toPrim $ pure $ (length s > 15))) >>=
            count

• Export Idris functions as Java classes, constructors, fields and functions
• Support adding annotions on the exported Java classes, constructors, fields and functions. We would now be able to write Spring Boot applications in Idris!

namespace Employee
    %export """
            jvm:public Employee
            {
                "annotations": [
                    {"Data": {}},
                    {"AllArgsConstructor": {
                        "exclude": ["id"]}},
                    {"NoArgsConstructor": {}},
                    {"Entity": {}}
                ],
                "fields": {
                    "id": {
                        "type": "java/lang/Long",
                        "annotations": [
                            {"Id": {}},
                            {"GeneratedValue": {}}
                        ]
                    },
                    "name": "String",
                    "role": "String"
                }
            }
            """
    public export
    Employee : Type
    Employee = Struct "io/github/mmhelloworld/helloworld/Employee" []

namespace EmployeeController

    %export """
            jvm:public EmployeeController
            {
                "fields": {
                    "employeeRepository": {
                        "modifiers": ["private", "final"],
                        "type": "EmployeeRepository"
                    }
                },
                "annotations": [
                    {"AllArgsConstructor": {}},
                    {"Getter": {}},
                    {"RestController": {}}
                ]
            }
            """
    public export
    EmployeeController : Type
    EmployeeController = Struct "io/github/mmhelloworld/helloworld/EmployeeController" []

    %foreign "jvm:.getEmployeeRepository"
    repository : EmployeeController -> PrimIO EmployeeRepository

    %export """
         jvm:public getEmployees!
         {
             "annotations": [
                 {"Get": ["/employees"]}
             ],
             "enclosingType": "EmployeeController",
              "arguments": [
                  {
                      "type": "EmployeeController"
                  }
              ],
              "returnType": "List<Employee>"
         }
     """
    employees : EmployeeController -> PrimIO (JList Employee)
    employees this = toPrim $ do
        employeeRepository <- fromPrim $ repository this
        findAll {id=Int64} (subtyping employeeRepository)

• Support generic type parameters like JpaRepository<Employee, Long>. Type variables are not supported in this PR.
• Generate no args constructor, all args constructor, required args constructor, equals, hashCode, toString , getters and setters from Idris while exporting a Java class
• Support accessing Java fields
• Support accessing class literals in Idris like classLiteral {ty=PayrollApplication}. Equivalent Java would be PayrollApplication.class
• Support Java's instanceof and reference equality to be able to implement Java methods like equals in Idris
• Support JVM arrays
• Avoid requiring explicit types for foreign calls. For the functions below, we, no longer, have to provide parameter and return types

namespace JInteger
    public export
    JInteger : Type
    JInteger = Struct "java/lang/Integer" []

    export
    %foreign "jvm:valueOf,java/lang/Integer"
    box : Int -> JInteger

    export
    %foreign "jvm:.intValue"
    unbox : JInteger -> Int

• Do not package generated class files from compiler output as Jar (Add an option to compile Idris JVM output to class files without packaging into JAR with runtime #159)