new price feed type "function" that recursively operates on price feeds taken as input

[nikhilsaraf]

Desired Behavior

I want to be able to combine price feeds by recursively operating on the results of these price feeds by using pre-defined functions.

Impact

The desired behavior will allow me to be more expressive about the value returned by the price feed.

Feature Suggestion

We can achieve the desired behavior by introducing a new type of price feed called function. the URL will be something like this: max(fixed/1.0,exchange/ccxt-kraken/XLM/USD/mid) and invert(exchange/ccxt-kraken/XLM/USD/mid).

Some functions will operate on one param, some will operate on more than one param. For now these can be a fixed number of params per function but can be expanded to variadic params in the future.

Tasks

• function type of feed
• max function
• invert function