site: faq: re-tell the history

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# Frequently asked questions
## hledger and Ledger
## hledger & Ledger
### How does hledger relate to Ledger ?
### History
hledger was inspired by John Wiegley's
[Ledger](http://ledger-cli.org). It is a friendly, mostly compatible
rewrite of Ledger in Haskell, begun in 2007 (Ledger started in 2003),
focussing on robustness, usability, ease of development, long-term
maintainability, and new experiments such as the
[web interface](manual.html#web). It currently lacks some of Ledger's
power-user features and speed. hledger stays compatible with Ledger
wherever possible, so that with a little care you can use both tools
on the same data files.
I was a happy user of John Wiegley's [Ledger](http://ledger-cli.org)
(begun in 2003) for some time. There was a long period of stagnation
in that project. I grew tired of bugs, missing and wrong documentation,
and explaining the situation to confused newcomers.
I really, truly needed a reliable accounting tool.
I really didn't want to spend time learning C++.
Longer answer: I was a happy Ledger user and contributor for some
time, then became too dissatisfied with bugs, missing/wrong
documentation and a long period of stagnation. I also wanted to try
implementing Ledger's brilliant design in the Haskell programming
language and ecosystem, which I believe has compelling advantages. I
try to build on Ledger's experience to make hledger easier to learn
and use, better documented, more appealing to work on; and to provide
alternate user interfaces (interactive, curses, web) to make it useful
to more people.
I felt Ledger could be implemented well and perhaps even more
successfully in the Haskell programming language, which has some
compelling advantages. (It encourages the coding style known as pure
functional programming, allowing more bug-free, concise and
maintainable software. It provides a more abstracted, portable
platform making installation easier. It is attractive for contributors
to work on.)
hledger builds quickly and has a complete and accurate manual, an
easier report query syntax, a data entry assistant, an optional web
interface (which often works on Ledger files too), and multi-column
balance reports. Ledger has additional power-user features (capital
gains tracking, periodic and modifier transactions, budget reports,
custom value expressions..) and it remains faster and more memory
efficient (for now!).
I couldn't ask John to start over - back then he was not the Haskell
lover he has since become! - so in 2007 I started prototyping a
parser, and kept going. My goals were to (a) learn how well Haskell
could do in this (simple, thought I) real-world application, and (b)
maybe, build on Ledger's experience to create a new implementation
prioritising ease of use. It would have simpler features, fewer bugs,
better documentation, and additional user interfaces.
The two projects collaborate freely. For some time we shared the
[#ledger](irc://irc.freenode.net/#ledger) IRC channel; in 2014 I added
a dedicated [#hledger](irc://irc.freenode.net/#hledger) channel.
I give back to Ledger by providing infrastructure
([ledger-cli.org](http://ledger-cli.org)), IRC support, [LedgerTips](http://twitter.com/LedgerTips) etc.
Later the Ledger project revived and attracted more contributors. The
two projects collaborate freely and ideas have travelled in both
directions. Having two independent somewhat-compatible
implementations has been quite helpful for testing and
troubleshooting, exploring the design space, and growing the "*ledger"
community. I also give back to Ledger by providing infrastructure
like [ledger-cli.org](http://ledger-cli.org),
[LedgerTips](http://twitter.com/LedgerTips), IRC support on #ledger
etc.
### And Ledger 4 ?
For some time hledger shared Ledger's IRC channel #ledger. In 2014 I
added the dedicated [#hledger](irc://irc.freenode.net/#hledger)
channel.
There is also a [ledger4](https://github.com/ledger/ledger4) on github; this is
John's own rewrite of the core of
Ledger 3 in haskell. It's an early library prototype, not a usable tool.
Perhaps some day hledger or something like it would use this as its foundation.
### Future ?
### File format differences ?
There is a [ledger4](https://github.com/ledger/ledger4) repo on
github; this is John's 2012/2013 rewrite of some parts of Ledger 3,
including the parser, in Haskell. We have a plan to add this parser to
hledger in 2015/2016, increasing its ability to read Ledger's files.
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 and hledger's more specialised syntax
(or keep it in separate files which you include only when appropriate).
### Features
Some Ledger syntax is parsed but ignored (such as
[automated transactions](http://ledger-cli.org/3.0/doc/ledger3.html#Automated-Transactions), [periodic transactions](http://ledger-cli.org/3.0/doc/ledger3.html#Periodic-Transactions), and
[historical prices](manual.html#historical-prices)).
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, such as with
[hledger comments](manual.html#comments) vs [Ledger comments](http://ledger-cli.org/3.0/doc/ledger3.html#Commenting-on-your-Journal),
or [balance assertions](manual.html#assertions-and-ordering).
Compared to Ledger, hledger builds quickly and has a complete and
accurate manual, an easier report query syntax, multi-column balance
reports, better depth limiting, an interactive data entry assistant,
and optional web and curses interfaces.
### Feature differences ?
hledger mimics a subset of [Ledger 3.x](http://ledger-cli.org), and adds some features of its own.
Compared to hledger, Ledger has additional power-user features such as
periodic and modifier transactions, budget reports, and the built in
value expressions language, and it remains faster and more memory
efficient (for now).
We currently support:
@ -74,19 +69,17 @@ We currently support:
- timelog format
- regular journal transactions
- multiple commodities
- fixed prices
- fixed transaction prices
- varying market prices
- 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
- the print, register & balance commands
- report filtering, using a different query syntax
We do not support:
- automated transactions
- value expressions
- fluctuating prices and historical price records
- display formats other than `d>[DATE]` or similar
- budget reports
And we add these commands:
@ -98,67 +91,26 @@ And we add these commands:
- incomestatement
- irr
- interest
- vty
- ui
- web
### Option/command differences ?
### File formats
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)
hledger's journal 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 and hledger's more specialised syntax
(or keep it in separate files which you include only when appropriate).
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
Some Ledger syntax is parsed but ignored (such as
[automated transactions](http://ledger-cli.org/3.0/doc/ledger3.html#Automated-Transactions)
and [periodic transactions](http://ledger-cli.org/3.0/doc/ledger3.html#Periodic-Transactions)).
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, such as with
[hledger comments](manual.html#comments) vs [Ledger comments](http://ledger-cli.org/3.0/doc/ledger3.html#Commenting-on-your-Journal),
or [balance assertions](manual.html#assertions-and-ordering).
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
```
### Other functionality differences ?
### Functional differences
- hledger recognises description and negative patterns by "desc:"
and "not:" prefixes, unlike Ledger 3's free-form parser
@ -175,9 +127,6 @@ entry DATE PAYEE AMT output a derived entry, based on the arguments
- hledger splits multi-day timelog sessions at midnight by default (Ledger does this with an option)
- 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.
@ -199,31 +148,23 @@ entry DATE PAYEE AMT output a derived entry, based on the arguments
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.
shell glob patterns (eg `include *.journal` ), which Ledger's 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#fixed-lot-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).
- Ledger allows amounts to have a fixed lot price (the {} syntax ?)
and a regular price in any order (and uses whichever appears
first). hledger requires the fixed lot price to come last (and
ignores it).
### Implementation differences ?
Ledger is written in C++, whereas hledger is written in [Haskell](http://haskell.org).
Haskell is a highly regarded up-and-coming programming 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.
## UI surprises
### Why does it complain about missing amounts ? I put one there
### Why does it complain about missing amounts even though I wrote one ?
This is an easy mistake at first. This journal entry:
```journal