localRead('/home/user/foo', {format: 'com.acme.extensions.data.FromJSONTxtConverter'})

works for reading but

localWrite('/home/user/bar.json', {format: 'com.acme.extensions.data.ToJSONTxtConverter'},$blah);

does not work for writing.

java.lang.Exception: formatter must implement ItemOutputStream java.lang.Exception: formatter must implement ItemOutputStream at com.ibm.jaql.io.stream.StreamOutputAdapter.initializeFrom (StreamOutputAdapter.java:57) at com.ibm.jaql.io.AbstractOutputAdapter.initializeFrom (AbstractOutputAdapter.java:48) at com.ibm.jaql.io.AdapterStore$OptionHandler.getAdapter (AdapterStore.java:305) at com.ibm.jaql.lang.expr.io.StWriteExpr.eval(StWriteExpr.java:129) at com.ibm.jaql.lang.expr.top.QueryExpr.eval(QueryExpr.java:92) at com.ibm.jaql.lang.Jaql.main1(Jaql.java:86) at JaqlShell.runInteractively(JaqlShell.java:173) at JaqlShell.main(JaqlShell.java:378)

These should use converters: com.ibm.jaql.io.hadoop.converter.FromJsonTextConverter and ToJsonTextConverter. Note that for the latter, you must also specify a configurator, e.g., ... -> write(hdfs('jaqlTest/test17out.dat', {converter: 'com.ibm.jaql.io.hadoop.converter.ToJsonTextConverter', configurator: 'com.ibm.jaql.io.hadoop.TextFileOutputConfigurator'}));