Analysis of formatting decimals

[joelburget]

We can't currently analyze formatting decimals due to the representation we use:

-- We model decimals as integers. The value of a decimal is the value of the
-- integer, shifted right 255 decimal places.
newtype Decimal = Decimal { unDecimal :: Integer }

Compare with these formatting examples:

pact> (format "{}" [1.5])
"1.5"
pact> (format "{}" [1.50])
"1.50"

It would be impossible to get these two different answers without explicitly tracking the decimal places a la Data.Decimal:

data DecimalRaw i = Decimal {
      decimalPlaces :: ! Word8,
      decimalMantissa :: ! i}

So, for this analysis we'll have to add a decimalPlaces field to our Decimal.