currencies.naaga

currencies: [GBP USD EUR NOK]
cache: []
<input id: amount value:: 0 />
<input id: from value:: USD />
<input id: to value:: GBP />
<div>
  if $from/value not in $currencies or $to/value not in $currencies
    <span class: error>"Sorry, unknown currency symbol"</span>
  else
    if [$from/value $to/value] not in cache
      cache[$from/value $to/value]: get-remote-exchange-rate $from/value $to/value
    try
      amount-as-number: to-number $amount/value
      <span>$amount/value $from/value "=" (cache[$from/value $to/value] * amount-as-number) $to/value</span>
    catch
      <span>"Sorry, the value is not a number"</span>
</div>