You can use btc-mode minor mode to show BTC rate in the mode-line or use this library in elisp code to get rates for something else.

• Get default rate (see Customization)

  (btc-get-rate)  ;; => 31015.6217
      

• Get rate by code

  (btc-get-rate-by-code "usd")  ;; => 31015.6217
      

(use-package btc
  :ensure nil
  :quelpa
  (btc :repo "pkulev/btc.el"
       :fetcher github :upgrade t)
  ;; NOTE: Don't do this if you wan't just use the library
  ;;       Minor mode is for showing rate in the mode-line.
  :config
  (btc-mode))

You have several customize variable to play with. use-packages’s :custom section is good for setting theese bad boys:

(use-package btc
  ;; other things you already know
  :custom
  (btc-format-string "%0.3f" "I need more precise result!")
  (btc-update-interval 2 "Every 2 seconds please, I have lots of CPU"))

btc-url

url for data source

Actually not useful, because getting rate value is tightly coupled with default source, but who knows, maybe I’ll abstract this eventually.

btc-format-string

format string for rate value

This string will be passed to format function each time rate updates.

btc-currency-code

currency code to convert BTC to

Tightly connected to couindesk API and JSON data it returns.

btc-currency-sign

currency sign to show with rate

For now you can’t customize it’s place. Definitely need to refactor this code.

btc-update-interval

BTC rate update interval

It’s one minute by default. Set in seconds.