hledger/doc/FAQ.md

# Frequently asked questions

## hledger and ledger

### How does hledger relate to ledger ?

hledger was inspired by and is partly a clone of John Wiegley's [ledger](http://ledger-cli.org).

I was a happy ledger user and contributor for some time; I still use it
occasionally. I wrote hledger because I wanted to develop financial tools
in the Haskell programming language and ecosystem, whose advantages I
believe are compelling. I have also tried to make hledger a little more
simple, usable, installable, documented, appealing to collaborators, and
to provide alternate user interfaces to make it more widely useful.

ledger has more advanced power-user features on the command-line
(periodic and modifier transactions, budgets, capital gains tracking,
value expressions, custom output formats, etc.) and it remains faster
and more memory efficient (for now!)...

hledger builds faster and has an up-to-date manual and an optional web
interface (which often works on ledger files too)...

The two projects collaborate freely.  We share the
[#ledger](irc://irc.freenode.net/#ledger) IRC channel but have
separate mail lists
([hledger list](http://groups.google.com/group/hledger/),
[ledger-cli list](http://groups.google.com/group/ledger-cli/)).  I try
to give back by providing infrastructure
([ledger-cli.org](http://ledger-cli.org)) and IRC support.
hledger stays compatible with ledger wherever possible, so that you
can often use both tools on the same data file.

Summary: hledger is a friendly, co-evolving, compatible rewrite of ledger
in Haskell, lacking some of ledger's power features and raw performance,
and focussing on robustness, usability, ease of development, and
experimental add-ons such as the [web interface](MANUAL.html#web).

### What are the feature differences ?

hledger mimics a subset of [ledger 3.x](http://ledger-cli.org), and adds some features of its own.

We currently support:

- ledger's journal format, mostly
- csv format
- timelog format
- regular journal transactions
- multiple commodities
- fixed prices and price history
- virtual postings
- print, register & balance commands
- filtering by many criteria, with different query syntax
- display expressions containing just a simple date predicate
- some basic output formatting

We do not support:

- automated transactions
- value expressions
- fluctuating prices
- display formats other than `d>[DATE]` or similar
- budget reports

And we add these commands:

- add
- balancesheet
- cashflow
- chart
- incomestatement
- irr
- interest
- vty
- web

ledger options and commands not supported include:

    Basic options:
    -o, --output FILE      write output to FILE
    -i, --init-file FILE   initialize ledger using FILE (default: ~/.ledgerrc)
    -a, --account NAME     use NAME for the default account (useful with QIF)
    
    Report filtering:
    -c, --current          show only current and past entries (not future)
        --period-sort EXPR sort each report period's entries by EXPR
    -L, --actual           consider only actual (non-automated) transactions
        --budget           generate budget entries based on periodic entries
        --add-budget       show all transactions plus the budget
        --unbudgeted       show only unbudgeted transactions
        --forecast EXPR    generate forecast entries while EXPR is true
    -l, --limit EXPR       calculate only transactions matching EXPR
    -t, --amount EXPR      use EXPR to calculate the displayed amount
    -T, --total EXPR       use EXPR to calculate the displayed total
    
    Output customization:
    -n, --collapse         Only show totals in the top-most accounts.
    -P, --by-payee         show summarized totals by payee
    -x, --comm-as-payee    set commodity name as the payee, for reporting
        --dow              show a days-of-the-week report
    -S, --sort EXPR        sort report according to the value expression EXPR
        --head COUNT       show only the first COUNT entries (negative inverts)
        --tail COUNT       show only the last COUNT entries (negative inverts)
        --pager PAGER      send all output through the given PAGER program
    -A, --average          report average transaction amount
    -D, --deviation        report deviation from the average
    -%, --percentage       report balance totals as a percentile of the parent
        --totals           in the "xml" report, include running total
    -j, --amount-data      print only raw amount data (useful for scripting)
    -J, --total-data       print only raw total data
    -y, --date-format STR  use STR as the date format (default: %Y/%m/%d)
        --balance-format      --register-format       --print-format
        --plot-amount-format  --plot-total-format     --equity-format
        --prices-format       --wide-register-format
    
    Commodity reporting:
        --price-db FILE    sets the price database to FILE (def: ~/.pricedb)
    -L, --price-exp MINS   download quotes only if newer than MINS (def: 1440)
    -Q, --download         download price information when needed
    -O, --quantity         report commodity totals (this is the default)
    -V, --market           report last known market value
    -g, --performance      report gain/loss for each displayed transaction
    -G, --gain             report net gain/loss
    
    Commands:
    xml      [REGEXP]...   print matching entries in XML format
    equity   [REGEXP]...   output equity entries for matching accounts
    prices   [REGEXP]...   display price history for matching commodities
    entry DATE PAYEE AMT   output a derived entry, based on the arguments

### What are the file format differences ?

hledger's file format is mostly identical with ledger's, by design.
Generally, it's easy to keep a journal file that works with both hledger
and ledger if you avoid ledger's most advanced features.

Some ledger features are parsed but ignored, eg:

- automated transactions ( = ... , ~ ... )
- fixed lot prices ( {...} )
- historical prices ( P ... )

Some features are not currently parsed and will cause an error, eg
ledger's more recent top-level directives. There can also be subtle
differences in parser behaviour.

### What other functionality differences are there ?

- hledger recognises description and negative patterns by "desc:"
  and "not:" prefixes, unlike ledger 3's free-form parser

- hledger doesn't require a space before command-line option
  values, eg `-fFILE` or `-f FILE` works

- hledger's weekly reporting intervals always start on mondays

- hledger shows start and end dates of the intervals requested,
  not just the span containing data

- hledger always shows timelog balances in hours

- hledger splits multi-day timelog sessions at midnight

- hledger doesn't track the value of commodities with varying
  price; prices are fixed as of the transaction date

- hledger's output follows the decimal point character, digit grouping,
  and digit group separator character used in the journal.

- hledger print shows amounts for all postings, and shows unit prices for
  amounts which have them. (This means that it does not currently print
  multi-commodity transactions in valid journal format.)

- hledger print ignores the --date2 flag, always showing both dates.
  ledger print shows only the secondary date with --aux-date, but not
  vice versa.

- hledger's default commodity directive (D) sets the commodity to be
  used for subsequent commodityless amounts, and also sets that
  commodity's display settings if such an amount is the first
  seen. ledger uses D only for commodity display settings and for the
  entry command.

- hledger generates a description for timelog sessions, instead of
  taking it from the clock-out entry

- hledger's [include directive](MANUAL.html#including-other-files) does not support
  shell glob patterns (eg `include *.journal` ), which ledger does.

- when checking [balance assertions](MANUAL.html#balance-assertions)
  hledger sorts the account's postings first by date and then (for
  postings with the same date) by parse order. ledger goes strictly by
  parse order.

- ledger allows amounts to have a
  [fixed lot price](MANUAL.html#prices) and a regular price in any
  order (and uses whichever appears first). hledger requires the fixed
  lot price to come last (and ignores it).

### How are the implementations different ?

ledger is written in C++, whereas hledger is written in the
[Haskell](http://haskell.org) programming language. 
Haskell is a highly regarded up-and-coming language that enables
a coding style known as pure functional programming, offering the
promise of more bug-free and maintainable software built in fewer
lines of code. Haskell also provides a more abstracted, portable
platform which can make deployment and installation easier in some
cases. Haskell also brings some new challenges such as managing memory
growth and laziness.