Euro Foreign Exchange Rates (Racket Usage)

Note: Code output provided for programs run in “Intermediate Student” language, but code should also run in #lang racket similarly.

Contents

Source

European Central Bank

http://www.ecb.europa.eu/stats/policy_and_exchange_rates/euro_reference_exchange_rates/html/index.en.html

Scroll to the “Downloads” section near the bottom to copy the links for CSV files for current and historical exchange rates.

Current Exchange Rates

Code

(require sinbad)

(define forex
  (sail-to "http://www.ecb.europa.eu/stats/eurofxref/eurofxref.zip?..."
           (format "csv") (load)))

(fetch-first-number forex "USD")

; filter out "Date" and extra "_col_..." field names...
(define currencies (filter (λ(s) (= 3 (string-length s)))
                           (field-list forex))) 
currencies

Output

1.1753
(list
 "CZK"
 "MYR"
 "AUD"
 ...
 "USD")

Metadata

Contains a dictionary mapping currency symbols to the current Euro-based exchange rate.

Historical Exchange Rates

Code

(define forex/hist
  (sail-to "http://www.ecb.europa.eu/stats/eurofxref/eurofxref-hist.zip?..."
           (format "csv") (load)))

(data-length forex/hist)                          ; ~4800 

(define all-usd (fetch forex/hist "Date" "USD"))  ; list of ~4000+ exchange rate values for USD

(define all-data (fetch forex/hist))              ; fetch all currencies, all dates
(first all-data)

(rest (assoc "Date" (first all-data)))
(rest (assoc "USD" (first all-data)))

Output

(list
 (cons "AUD" 1.5248)
 (cons "BGN" 1.9558)
 (cons "BRL" 3.803)
 ...
 (cons "Date" "2017-10-26")
 ...
 (cons "USD" 1.1753)
 (cons "ZAR" 16.739)
 (cons "col-42" ""))
 
"2017-10-26"

1.1753

Metadata

Contains a list of dictionaries mapping currency symbols to exchange rates. Each record also contains a Date. The records do not include every date (maybe holidays/weekends are not included?).