A commodity directive that doesn't specify the decimal point character
increases ambiguity and the chance of misparsing numbers, especially
as it overrides all style information inferred from the journal amounts.
In some cases it caused amounts with a decimal point to be parsed as if
with a digit group separator so 1.234 became 1234.
We could augment it with extra info from the journal amounts, when available,
but it would still be possible to be ambiguous, and that won't be obvious.
A commodity directive is what we recommend to nail down the style.
It seems the simple and really only way to do this reliably is to require
an explicit decimal point character. Most folks probably do this already.
Unfortunately, it makes another potential incompatiblity with ledger and
beancount journals. But the error message will be clear and easy to
work around.
Inferred amounts now have the appropriate standard amount style applied.
And when checking for balanced transactions, amount styles declared with
commodity directives are also used (previously only inferred amount styles were).
Income, liability and equity balances, which until now we have
always displayed as negative numbers, are now shown as normally positive
by these reports.
Negative numbers now indicate a contra-balance (eg an overdrawn
checking account), a net loss, a negative net worth, etc.
This makes these reports more like conventional financial statements,
and easier to read and share with normal people.
Now we have:
-- | Sorted unique account names posted to by this journal's transactions.
journalAccountNamesUsed :: Journal -> [AccountName]
-- | Sorted unique account names implied by this journal's transactions -
-- accounts posted to and all their implied parent accounts.
journalAccountNamesImplied :: Journal -> [AccountName]
-- | Sorted unique account names declared by account directives in this journal.
journalAccountNamesDeclared :: Journal -> [AccountName]
-- | Sorted unique account names declared by account directives or posted to
-- by transactions in this journal.
journalAccountNamesDeclaredOrUsed :: Journal -> [AccountName]
-- | Sorted unique account names declared by account directives, or posted to
-- or implied as parents by transactions in this journal.
journalAccountNamesDeclaredOrImplied :: Journal -> [AccountName]
-- | Convenience/compatibility alias for journalAccountNamesImpliedOrUsed.
journalAccountNames :: Journal -> [AccountName]
