Readers add support for new file formats.

To add a new reader, add a service named after the file format, prefixed with "haplo:data-import-framework:reader:".

The service is called with two arguments, a BinaryData object and the specification from the control file to allow options to be specified.

It must return a function which takes a single iterator argument, which it should call once for each Record in the file. The record should only contain data types which are JSON compatible.

In your implementation, do not call O.file() on the BinaryData object, as for some uses of the data import framework, this would unnecessarily add files to the file store.

Example reader

To create a simple-json reader which reads a JSON file containing an array of records.

    function(file, spec) {
        let parsed = JSON.parse(file.readAsString("utf-8"));
        return function(iterator) {
            _.each(parsed, iterator);

A control file which uses this reader would include:

    "files": {
        "users": {
            "read": "simple-json"