Temporary Functions

These functions only runs while the connection is open. Once closed, the function disappears.

Creating a Temporary Function

Prepare

Open the Chainless App. Then, click the button in the bottom-right corner to expand the menu. Select "Create Temporary Function".

At this page, you can write your function code as a single JavaScript or Python file. Temporary functions may not include additional dependencies, so they are limited in functionality. Edit the code box to implement your function.

Code

The code is generally structured in the following manner: JS

(function(functionState, blockWithMeta) {
  let state = { ...functionState.state }
  // ...
  return state
})

Note: The entire function must be wrapped in (parenthesis).

Python

import polyglot
@polyglot.export_value
def apply_block(stateWithChains, blockWithMeta):
  if(stateWithChains["state"] is not None):
    state = stateWithChains["state"]
    # Modify state
    return state
  else:
    state = {}
    # Initialize state
    return state

Note: The "polyglot" statements are required Note: Python functionality is in early-preview

This function accepts a function state and a new block, and produces a new state. It is invoked over-and-over again by the backend as new blocks arrive.

The functionState object contains .state and .chainStates fields. .state is the JSON result of the previous invocation of this function. .chainStates is a key-value mapping from "chain name" to "block ID".

The blockWithMeta object contains .meta and .block fields. .meta includes information like .chain, .blockId, and .height. .block contains the raw JSON-encoded data of the block.

Historical Blocks

You can optionally select a Start Time from which blocks should be retroactively applied. For example, you can instruct the function to apply all blocks from yesterday before applying new blocks.

Run

Finally, click Run. Your function will start running on a Chainless server, and the state will be streamed back to you as it is updated.