jx_repl: A Tool for JX Language Exploration

Overview

This is a brief guide on how to use the jx_repl command-line utility, which acts as an explorer for the JX workflow language. It's recommended that you follow the JX Tutorial first or simultaneously when using this tool.

Usage

To use this interactive utility, simply run

  $ jx_repl

Commands

jx_repl reserves a number of symbols in the context, which act as commands when entered:

Command Description
help display a help message which lists details on reserved commands
in_# return the #'th input query
out_# return the result of in_#
functions display a list of functions supported by the JX language
values display a list of values supported by the JX language
operators display a list of operators supported by the JX language
catalog fetch the catalog data from http://catalog.cse.nd.edu:9097
exit exit the program
quit same as "exit"

Examples

Start the utility 

$ jx_repl
Welcome to the JX Language Explorer.

Type 'help' for help

in_0  : ...

Enter any valid JX expression:

$ jx_repl
...
in_0  : [ "file" + x + ".txt" for x in range(3) ]
out_0 :
[
  "file0.txt",
  "file1.txt",
  "file2.txt"
]

Fetch the catalog data:

$ jx_repl
...
in_1  : catalog
out_1 :
[
  {
    "name":NAME,
    "lastheardfrom":1620308581,
    "address":ADDRESS,
    ...
    "type":"wq_factory"
  },
  ...
]

Perform operations on previous output

$ jx_repl
...
in_2  : select(out_1, type=="wq_master")
out_2 :
[

  {
    "name":NAME,
    "lastheardfrom":1620308755,
    "address":ADDRESS,
    "tasks_total_disk":0,
    "tasks_total_memory":0,
    ...
    "type": wq_master
  }
  ...
]

Do more operations on previous output

$ jx_repl
...
in_3  : join(project(out_2, name), ", ")
out_3 : NAME_1, NAME_2, NAME_3, ..., NAME_N

Now, fetch the query used to attain that output

$ jx_repl
...
in_4  : in_4
out_4 : join(project(select(fetch("http://catalog.cse.nd.edu:9097/query.json"),type=="wq_master"),name),", ")

Call one of reserved commands

$ jx_repl
...
in_5  : help

  help          display this message
  functions     display a list of functions supported by the JX language
  values        display a list of values supported by the JX language
  operators     display a list of operators supported by the JX language
  in_#          the #'th input query
  out_#         result of in_#
  catalog       alias to fetch catalog data
  quit|exit     exit program