main.ls

export function mount-storage (plx, schema, table, cb)
  # import a package
  next <- plx.import-bundle-funcs 'jsonpatch', require.resolve("jsonpatch/package.json")
  <- next!
  <- plx.mk-user-func 'plv8x.json apply_patch(json, json[])', 'jsonpatch:apply_patch'
  # import a module (without package.json)
  next <- plx.import-bundle-funcs 'pgrest_schemaless', require.resolve('./user_func')
  <- next!
  # ...

test.ls

storage <- mount-storage plx, SCHEMA, TABLE
err, {row}? <- plx.conn.query "select pgrest_schemaless_set($1) as ret" [{}]
throw err if err

# Uncaught Error: TypeError: Cannot read property 'pgrest_schemaless_set' of undefined
#   at Connection.<anonymous> (/Users/poga/MyProject/pgrest/pgrest-schemaless/node_modules/pgrest/node_modules/plv8x/node_modules/pg/lib/native/index.js:202:17)
#   at Connection.EventEmitter.emit (events.js:95:17)

user_func.ls

export function pgrest_schemaless_set (params)
  query = "select apply_patch('{}'::json, ARRAY['{\"op\": \"add\", \"path\": \"/new\", \"value\": \"new\"}'::json]) as ret;"
  console.log query
  return plv8.execute query
pgrest_schemaless_set.$plv8x = '(plv8x.json):plv8x.json'