# Using jodliterate

The JODSOURCE addon, (a part of the JOD system), contains a handy literate programming tool that enables the generation of beautiful J source code documents.

The Bible, Koran, and Bhagavad Gita of Literate Programming is Donald Knuth’s masterful tome of the same name.

Knuth applied Literate Programming to his $\TeX$ systems and produced what many consider enduring masterpieces of program documentation.

jodliterate is certainly not worthy of $\TeX$ level accolades but with a little work it’s possible to produce fine documents. This J kernel notebook outlines how you can install and use jodliterate. Jupyter notebooks are typically executed but to accommodate J users that do hot have Jupyter this notebook is also available on GitHub as a static PDF document.

#### Notebook Preliminaries

In [1]:
NB. show J kernel version
9!:14 ''
j901/j64avx/windows/release-e/commercial/www.jsoftware.com/2020-01-29T11:15:50
In [2]:
NB. load JOD in a clear base locale

NB. The distributed JOD profile automatically RESETME's.
NB. To safely use dictionaries with many J tasks they must
NB. be READONLY. To prevent opening the same put dictionary
NB. READWRITE comment out (dpset) and restart this notebook.
dpset 'RESETME'

NB. Converting Jupyter notebooks to LaTeX is
NB. simplified by ASCII box characters.
portchars ''

NB. Verb to show large boxed displays in
NB. the notebook without ugly wrapping.
sbx_ijod_=: ' ... ' ,"1~ 75&{."1@":

#### Installing jodliterate

To use jodliterate you need to:

1. Install a current version of J.
2. Install the J addons JOD, JODSOURCE, and JODDOCUMENT.
3. Build the JOD development dictionaries from JODSOURCE.
4. Install a current version of pandoc.
5. Install a current version of $\TeX$ and $\LaTeX$.
6. Make the jodliterate J script.
7. Run jodliterate on a JOD group with pandoc compatible document fragments.
8. Compile the files of the previous step to produce a PDF

When presented with long lists of program prerequisites my impulse is to run! Life is too short for configuration wars. Everything should be easy. Installing jodliterate requires more work than phone apps but compared to enterprise installations setting up jodliterate is trivial. We’ll go through it step by step.

#### Step 1: Install a current version of J

J is freely available at jsoftware.com. J installation instructions can be found on the J Wiki on this page.

Note: JOD runs on Windows, Linux, and MacOS versions of J, hence these are the only platforms that currently support jodliterate.

#### Step 2: Install the J addons JOD, JODSOURCE and JODDOCUMENT

After installing J install the J addons. J addons are installed with the J package manager pacman. Pacman has three IDE flavors: a command-line flavor and two GUI flavors. The GUI flavors depend on JQT or JHS. The GUI flavors of pacman are only available on some versions of J whereas the command line version is part of the base J install and is available on all platforms.

I install all the addons. I recommend that you do the same.

JOD depends on some J modules like jfiles, regex, and task that are sometimes distributed as addons. If you install all addons JOD’s modules and dependents are both installed.

#### Installing addons with command line pacman

Start J and do:

In [3]:
NB. install J addons with command-line pacman

In [4]:
'help' jpkg ''   NB. what can you do for me?
Valid options are:
history, install, manifest, remove, reinstall, search,

https://code.jsoftware.com/wiki/JAL/Package_Manager/jpkg

In [5]:
NB. see https://code.jsoftware.com/wiki/Pacman

NB. uncomment next line if addons not installed
NB. 'install' jpkg '*'  NB.
In [6]:
3 {. 'showinstalled' jpkg '' NB. first few installed addons
+---------+------+------+-----------------------------+
|api/expat|1.0.11|1.0.11|libexpat                     |
+---------+------+------+-----------------------------+
|api/gles |1.0.31|1.0.31|Modern OpenGL API            |
+---------+------+------+-----------------------------+
|api/java |1.0.2 |1.0.2 |api: Java to J shared library|
+---------+------+------+-----------------------------+
In [7]:

#### Installing addons with JQT GUI pacman

I mostly use the Windows JQT version of pacman to install and maintain J addons. You can find pacman on the tools menu.

pacman shows all available addons and provides tools for installing, updating, and removing them.

The GUI version is easy to use. Press the Select All button and then press the Install button to install all the addons. To update addons select the Upgrades menu and select the addons you want to update.

#### Step 3: Build the JOD development dictionaries from JODSOURCE

JOD source code is distributed in the form of JOD dictionary dumps. Dictionary dumps are large J scripts that serialize JOD dictionaries. Dumps contain everything stored in dictionaries. You will find source code, binary data, test scripts, documentation, build macros, and more in typical JOD dictionaries.

jodliterate is stored as a JOD dictionary group. A dictionary group is simply a collection of J words with optional header and post-processor scripts. JOD generates J scripts from groups. Before we can make jodliterate we must load the JOD development dictionaries. The JODSOURCE addon includes a J script that loads development dictionaries.

Again, start J and do:

In [8]:
require 'general/jod'
In [9]:
NB. set a JODroot user folder
NB. if not set /jod/ is the default

NB. use paths for your OS
UserFolders_j_=: UserFolders_j_ , 'JODroot';'c:/temp'

UserFolders_j_ {~ (0 {"1 UserFolders_j_) i. <'JODroot'
+-------+-------+
|JODroot|c:/temp|
+-------+-------+
In [10]:
if. +./ (;:'joddev jod utils') e. od '' do.
'dev dictionaries exist'
else.
end.
)

dev dictionaries exist
In [11]:
NB. joddev, jod, utils should exist

(;:'joddev jod utils') e. od ''
1 1 1

#### Step 4: Install a current version of pandoc

pandoc is easily one of the most useful markup utilities on the intertubes. If you routinely deal with markup formats like markdown, XML, $\LaTeX$, json and you aren’t using pandoc you are working too hard.

Be lazy! Install pandoc.

jodliterate uses the task addon to shell out to pandoc. Versions of pandoc after 2.9.1.1 support J syntax high-lighting.

In [12]:
NB. show pandoc version from J - make sure you are running
NB. versions in many locations on various systems.

ppath=: '"C:\Program Files\Pandoc\pandoc"'
THISPANDOC_ajodliterate_=: ppath
shell THISPANDOC_ajodliterate_,' --version'
pandoc 2.9.1.1
Compiled with pandoc-types 1.20, texmath 0.12, skylighting 0.8.3
Default user data directory: C:\Users\john\AppData\Roaming\pandoc
Web:  https://pandoc.org
This is free software; see the source for copying conditions.
There is no warranty, not even for merchantability or fitness
for a particular purpose.

In [13]:
NB. make sure your version of pandoc
NB. supports J syntax-highlighting

NB. appends line feed character if necessary
tlf=:] , ((10{a.)"_ = {:) }. (10{a.)"_

NB. J is on the supported languages list
pcmd=: THISPANDOC_ajodliterate_,' --list-highlight-languages'
(<;._2 tlf (shell pcmd) -. CR) e.~ <,'j'
1

#### Step 5: Install a current version of LaTeX

jodliterate uses $\LaTeX$ to compile PDF documents. When setjodliterate runs it sets an output directory and writes a $\LaTeX$ preamble file JODLiteratePreamble.tex to it. It’s a good idea to review this file to get an idea of the $\LaTeX$ packages jodliterate uses. It’s possible that some of these packages are not in your $\LaTeX$ distribution and will have to be installed.

To ease the burden of $\LaTeX$ package maintenance I use freely available $\TeX$ versions that automatically install missing packages.

1. On Windows I use MiKTeX
2. On other platforms I use TeXLive

If your system automatically installs packages the first time you compile jodliterate output it may fetch missing packages from The Comprehensive $\TeX$ Archive Network (CTAN). If new packages are installed reprocess your files a few times to insure all the required packages are downloaded and installed.

#### Step: 6 Make the jodliterate J script

Once the JOD development dictionaries are built (Step 3) making jodliterate is easy. Start J and do:

In [14]:
require 'general/jod'

NB. open dictionaries
od ;:'joddev jod utils' [ 3 od ''
+-+--------------------+------+---+-----+
|1|opened (rw/ro/ro) ->|joddev|jod|utils|
+-+--------------------+------+---+-----+
In [15]:
NB. generate jodliterate
sbx mls 'jodliterate'
+-+--------------------+------------------------------------+               ...
+-+--------------------+------------------------------------+               ...

mls creates a standard J load script. Once generated this script can be loaded with the standard J load utility. You can test this by restarting J without JOD and loading jodliterate.

In [16]:
NB. (jodliterate) interface word(s):
NB. --------------------------------
NB. THISPANDOC      NB. full pandoc path - use (pandoc) if on shell path
NB. grplit          NB. make latex for group (y)
NB. ifacesection    NB. interface section summary string
NB. ifc             NB. format interface comment text
NB. setjodliterate  NB. prepare LaTeX processing - sets out directory writes preamble

NOTE: adjust pandoc path if version (pandoc 2.9.1.1) is not >= 2.9.1.1

#### Step 7: Run jodliterate on a JOD group with pandoc compatible document fragments

This sounds a lot worse than it is. There is a group in utils called sunmoon that has an interesting pandoc compatible document fragment.

Start J and do:

In [17]:
require 'general/jod'

od 'utils' [ 3 od ''
+-+--------------+-----+
|1|opened (ro) ->|utils|
+-+--------------+-----+
In [18]:
NB. display short explanations for (sunmoon) words
sbx hlpnl }. grp 'sunmoon'
+-----------------+-------------------------------------------------------- ...
|IFACEWORDSsunmoon|interface words (IFACEWORDSsunmoon) group                ...
|NORISESET        |indicates sun never rises or sets in (sunriseset0) and ( ...
|ROOTWORDSsunmoon |root words (ROOTWORDSsunmoon) group                      ...
|arctan           |arc tangent                                              ...
|calmoons         |calendar dates of new and full moons                     ...
|fromjulian       |converts Julian day numbers to dates, converse (tojulian ...
|moons            |times of new and full moons for n calendar years         ...
|round            |round (y) to nearest (x) (e.g. 1000 round 12345)         ...
|sunriseset0      |computes sun rise and set times - see group documentatio ...
|sunriseset1      |computes sun rise and set times - see group documentatio ...
|tabit            |promotes only atoms and lists to tables                  ...
|today            |returns todays date                                      ...
|yeardates        |returns all valid dates for n calendar years             ...
+-----------------+-------------------------------------------------------- ...
In [19]:
NB. display part of the (sunmoon) group document header
NB. this is pandoc compatible markdown - note the LaTeX
NB. commands - pandoc allows markdown/LaTeX mixtures
900 {. 2 9 disp 'sunmoon'
ï»¿sunmoon is a collection of basic astronomical algorithms
The key verbs are moons, sunriseset0 and sunriseset1.
All of these verbs were derived from BASIC programs published
in *Sky & Telescope* magazine in the 1990's. The rest of
the verbs in sunmoon are mostly date and trigonometric
utilities.

\subsection{\texttt{sunmoon} Interface}

~~~~ { .j }
calmoons      NB. calendar dates of new and full moons
moons         NB. times of new and full moons for n calendar years
sunriseset0   NB. computes sun rise and set times - see group documentation
sunriseset1   NB. computes sun rise and set times - see group documentation
~~~~

\subsection{\textbf\texttt{sunriseset0} \textsl{v--} sunrise and sunset times}

This  verb has been adapted from a BASIC program submitted by
Robin  G.  Stuart  *Sky & Telescope's*  shortest  sunrise/set
program  cont
In [20]:
NB. run jodliterate on (sunmoon)
require 'jodliterate'

NB. set the output directory - when
NB. running in Jupyter use a subdirectory

ltxpath=: 'C:\Users\john\AnacondaProjects\testfolder\grplit\'
setjodliterate ltxpath
+-+-------------------------------------------------+
|1|C:\Users\john\AnacondaProjects\testfolder\grplit\|
+-+-------------------------------------------------+
In [21]:
NB. (grplit) returns a list of generated
NB. LaTeX and command files. The *.bat
NB. file compiles the generated LaTeX

,. grplit 'sunmoon'
+-----------------------------------------------------------------+
|1                                                                |
+-----------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\sunmoon.tex     |
+-----------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\sunmoontitle.tex|
+-----------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\sunmoonoview.tex|
+-----------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\sunmooncode.tex |
+-----------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\sunmoon.bat     |
+-----------------------------------------------------------------+

#### Step 8: Compile the files of the previous step to produce a PDF

In [22]:
_250 {. shell ltxpath,'sunmoon.bat'
gular.otf><c:/program files/miktex 2.9/fonts/ope
ntype/public/lm/lmmono12-regular.otf>
Output written on sunmoon.pdf (22 pages, 107711 bytes).
Transcript written on sunmoon.log.

(base) C:\Users\john\AnacondaProjects\testfolder\grplit>endlocal

In [23]:
NB. uncomment to display generated PDF
NB. shell ltxpath,'sunmoon.pdf'

#### Storing jodliterate pandoc compatible document fragments in JOD

Effective use of jodliterate requires a melange of Markdown, $\LaTeX$, JOD, and J skills combined with a healthy attitude about experimentation. You have to try things and see if they work!

However, before you can try jodliterate document fragments you have put them in JOD dictionaries.

jodliterate uses two types of document fragments:

1. markdown overview group documents.
2. $\LaTeX$ overview macros.

Markdown group documents are transformed by pandoc into $\LaTeX$ but the overview macros are not altered in any way. This enables the use of arbitrarily complex $\LaTeX$. The following examples show how to insert document fragments.

#### Create a jodliterate Demo Dictionary

In [24]:
NB. create a demo dictionary - (didnum) insures new name
require 'general/jod'

NB. new dictionary in default JOD directory
sbx newd itslit_ijod_=: 'aaa',":didnum_ajod_ ''
+-+---------------------+------------------------------------------+------- ...
|1|dictionary created ->|aaa327403631806685638405507439206657280913|c:/user ...
+-+---------------------+------------------------------------------+------- ...
In [25]:
NB. 1 if new dictionary created
(<itslit) e. od ''
1
In [26]:
od itslit [ 3 od '' NB. open only new dictionary
+-+--------------+------------------------------------------+
|1|opened (rw) ->|aaa327403631806685638405507439206657280913|
+-+--------------+------------------------------------------+
In [27]:
NB. define some words
freq=:~. ; #/.~
movmean=:-@[ (+/ % #)\ ]
geomean=:# %: */
bmi=: 704.5"_ * ] % [: *: [
polyprod=:+//.@(*/)

wlst=: ;:'freq movmean geomean bmi polyprod'

NB. put in dictionary
put wlst

NB. short word explanations
t=: ,:  'freq';'frequency distribution'
t=: t , 'movmean';'moving mean'
t=: t , 'geomean';'geometric mean of a list'
t=: t , 'bmi';'body mass index - (x) inches (y) lbs'
t=: t , 'polyprod';'polynomial product'

0 8 put t
+-+-------------------------------+------------------------------------------+
|1|5 word explanation(s) put in ->|aaa327403631806685638405507439206657280913|
+-+-------------------------------+------------------------------------------+
In [28]:
NB. make header and macro groups
grp 'litmacro'  ; wlst
+-+--------------------------+------------------------------------------+
|1|group <litmacro> put in ->|aaa327403631806685638405507439206657280913|
+-+--------------------------+------------------------------------------+
In [29]:
+-+-------------------+------------------------------------------+
|1|1 word(s) put in ->|aaa327403631806685638405507439206657280913|
+-+-------------------+------------------------------------------+

#### Use Group Document Overview Markdown

In [30]:
litheader is a markdown demo group.

This markdown text will be
[transmogrified](https://calvinandhobbes.fandom.com)
by pandoc to \LaTeX. A group interface will be
generated from the IFACEWORDSlitheader
list. Interface lists are usually, but
not always, associated with a *class group*.

{~{insert_interface_md_}~}
)

NB. store markdown as a JOD group document
+-+-----------------------------+------------------------------------------+
|1|1 group document(s) put in ->|aaa327403631806685638405507439206657280913|
+-+-----------------------------+------------------------------------------+
In [31]:
NB. run jodliterate on group
ltxpath=: 'C:\Users\john\AnacondaProjects\testfolder\grplit\'
setjodliterate ltxpath
+--------------------------------------------------------------+
+--------------------------------------------------------------+
In [32]:
NB. compile latex
lar.otf><c:/program files/miktex 2.9/fonts/o
pentype/public/lm/lmmono12-regular.otf>
Output written on litheader.pdf (4 pages, 47726 bytes).

(base) C:\Users\john\AnacondaProjects\testfolder\grplit>endlocal

In [33]:
NB. uncomment to show PDF

#### Use Macro Overview LaTeX

In [34]:
NB. add a LaTeX overview - this code will not
NB. be altered by jodliterate the suffix
NB. '_oview_tex' is required to associate
NB. the overview with the group 'litmacro'

litmacro_oview_tex=: (0 : 0)

This \LaTeX\ code will not be
touched by \texttt{jodliterate}.

Truth management is enabled.''

\emph{Excerpt from an actual business document!}
Obviously composed in an irony free zone.

\subsection{Some Complicated \LaTeX}

\medskip

$\frac{1}{\Bigl(\sqrt{\phi \sqrt{5}}-\phi\Bigr) e^{\frac25 \pi}} = 1+\frac{e^{-2\pi}} {1+\frac{e^{-4\pi}} {1+\frac{e^{-6\pi}} {1+\frac{e^{-8\pi}} {1+\ldots} } } }$

)

NB. store LaTeX as JOD text macro
4 put 'litmacro_oview_tex';LATEX_ajod_;litmacro_oview_tex
+-+--------------------+------------------------------------------+
|1|1 macro(s) put in ->|aaa327403631806685638405507439206657280913|
+-+--------------------+------------------------------------------+
In [35]:
NB. run jodliterate on group
{: grplit 'litmacro'
+-------------------------------------------------------------+
|C:\Users\john\AnacondaProjects\testfolder\grplit\litmacro.bat|
+-------------------------------------------------------------+
In [36]:
NB. compile latex
_250 {. shell ltxpath,'litmacro.bat'
e1/public/lm/lmsy6.pfb><C:/Program Files/MiKTeX 2.9/fonts/type1/public/lm/lms
y8.pfb>
Output written on litmacro.pdf (4 pages, 138976 bytes).
Transcript written on litmacro.log.

(base) C:\Users\john\AnacondaProjects\testfolder\grplit>endlocal

In [37]:
NB. display PDF
NB. shell ltxpath,'litmacro.pdf'

#### Using jodliterate with larger J systems

The main jodliterate verb grplit works with single JOD groups. Larger systems are typically made from many groups. JOD macro and test scripts are one way to work around this limitation. The JOD development dictionaries contain several macros that illustrate this approach.

In [38]:
od ;:'joddev jod utils' [ 3 od ''

NB. list macros with substring 'latex'
4 2 dnl 'latex'
+-+-------------+---------------------+
|1|buildjodlatex|buildjodliteratelatex|
+-+-------------+---------------------+
In [39]:
NB. display start of macro that
NB. applies jodliterate to JOD code
250 {. 4 disp 'buildjodlatex'
NB.*buildjodlatex s--  generates syntax highlighted JOD source LaTeX.
NB.
NB. Files are written to the put dictionary's document directory.
NB.
NB. assumes: current versions of pandoc (pandoc 2.9.1.1 or later)
NB.          check noun (THISPANDOC

#### Final Remarks

jodliterate is an idiosyncratic anal-retentive software utility; it’s mainly for people that consider source code an art form. Nobody likes ugly undocumented art!

If you have any questions, suggestions, or complaints please leave a comment on this post. To include others join one of J discussion forums and post your queries there.

May the source be with you!

WordPress conversion from UsingJodliterate.ipynb by nb2wp v0.3.1

# SWAG a J/EXCEL/GIT Personal Cash Flow Forecasting Mob

While browsing in a favorite bookstore with my son, I spotted a display of horoscope themed Christmas tree ornaments. The ornaments were glass balls embossed with golden birth signs like Aquarius, Gemini, Cancer, et cetera, and a descriptive phrase that “summed up” the character of people born under a sign. Below my birth sign golden text declared, “Imaginative and Suspicious.”

I said to my son, “I hate it when astrological rubbish is right.”

I am imaginative and suspicious; it’s a curse. When it comes to money my “suspicious dial” is permanently set on eleven. I assume everyone is out to cheat and defraud me until there is overwhelming evidence to the contrary. Paranoia is generally crippling but when it comes to cold hard cash it’s a sound retention strategy.

Prompted by an eminent life move, I found myself in need of a cash flow forecasting tool. Normal people deal with forecasting problems by buying standard finance programs or cranking up spreadsheets; imaginative and suspicious people roll their own.

## SWAG

SWAG, (Silly Wild Ass Guess), is a hybrid J/EXCEL/GIT mob1 that meets my eccentric needs. I wanted a tool that:

1. Abstracted away accounting noise.
2. Was general and flexible.
3. Used highly portable, durable, and version control friendly inputs and outputs.
4. Reflected what ordinary people, not tax accountants, actually do with money.
5. Is open source and unencumbered by parasitic software patents.

Amazingly, my short list of no-brainer requirements eliminates most standard finance programs. Time to code!

## SWAG Inputs

The bulk of SWAG is a JOD generated self-contained J script. You can peruse the script here. SWAG inputs and outputs are brain-dead simple TAB delimited text tables. Inputs consist of monthly, null-free, numeric time series tables, scenario tables, and name cross-reference tables. Outputs are simple, null-free, numeric time series tables. Input and output time series tables have identical formats.

A few examples will make this clear. The following is a typical SWAG input and output time series table.

Date        E0      E1       E2      E3  E4     E5  E6  E7  E8  EC  EF  Etotal   I0       I1  I2  I3  I4  I5  IC  Itotal   R0         R1        R2  R3  Rtotal     D0  D1  D2  D3  D4  Dtotal  BB       NW         U0         U1  U2  U3
2015-09-01  912.00  1650.00  100.00  0   50.00  0   0   0   0   0   0   2712.00  4800.00  0   0   0   0   0   0   4800.00  130000.00  25000.00  0   0   155000.00  0   0   0   0   0   0       2088.00  157088.00  155000.00  0   0   0
2015-10-01  912.00  1656.88  100.00  0   50.00  0   0   0   0   0   0   2718.88  4806.00  0   0   0   0   0   0   4806.00  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2087.13  159291.79  0          0   0   0
2015-11-01  912.00  1663.78  100.00  0   50.00  0   0   0   0   0   0   2725.78  4812.01  0   0   0   0   0   0   4812.01  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2086.23  161378.02  0          0   0   0
2015-12-01  912.00  1670.71  100.00  0   50.00  0   0   0   0   0   0   2732.71  4818.02  0   0   0   0   0   0   4818.02  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2085.31  163463.33  0          0   0   0
2016-01-01  912.00  1677.67  100.00  0   50.00  0   0   0   0   0   0   2739.67  4824.05  0   0   0   0   0   0   4824.05  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2084.37  165547.70  0          0   0   0
2016-02-01  912.00  1684.66  100.00  0   50.00  0   0   0   0   0   0   2746.66  4830.08  0   0   0   0   0   0   4830.08  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2083.41  167631.12  0          0   0   0
2016-03-01  912.00  1691.68  100.00  0   50.00  0   0   0   0   0   0   2753.68  4836.11  0   0   0   0   0   0   4836.11  130054.17  25062.50  0   0   155116.67  0   0   0   0   0   0       2082.43  169713.55  0          0   0   0

The first header line is a simple list of names. The first name “Date” heads a column of first of month dates in YYYY-MM-DD format. The SWAG clock has month resolution and dates are the only nonnumeric items. Names beginning with “E” like E0, E1, …, are aggregated expenses. Names beginning with “I” like I0, I1, I2 … are income totals. “R” names are reserves: basically savings, investments, equity and so forth. “D” names are various debts. BB is basic period balance, NW is period net worth and “U” names are utility series. Utility series facilitate calculations. Remaining names are self-explanatory totals. Be aware that this table has been formatted for this blog. Examples of raw input and output tables can be found here.

The next ingredient in the SWAG stew is what many call a scenario. A scenario is a collection of prospective assumptions and actions. In one scenario you buy a Mercedes and assume interest rates remain low. In another, you take the bus and rates explode. When forecasting I evaluate five basic scenarios, grim, pessimistic, expected, optimistic, and exuberant. Being a negative Debbie Downer type I rarely invest time in exuberant scenarios. I concentrate on grim and pessimistic scenarios because once you are mentally prepared for the worst anything better feels like a lottery win.

The following is a typical SWAG scenario table. Scenario tables, like time series tables, are simple TAB delimited text files.

Name         Scenario On Group       Value  OnDate     OffDate    Method   MethodArguments                                                Description
reservetotal s0          assumptions 0      2015-09-01 2015-10-01 assume   RSavings=. 0.5 [ RInvest=. 3 [ REquity=. 3 [ ROther=. 1        annual nominal percent reserve growth or decline during period
car          s0                      50     2015-09-01 2035-08-01 history                                                                 annualized car maintenance until first death
house        s0                      912    2015-09-01 2016-08-01 history  BackPeriods=.1                                                 current rent until move
insurance    s0                      100    2015-09-01 2035-08-01 history                                                                 car insurance
living       s0                      1650   2015-09-01 2044-01-01 history  YearInflate=.5                                                 normal monthly living expenses
salary       s0                      4800   2015-09-01 2016-08-01 history  BackPeriods=.4 [ YearInflate=.1.5                              maintain net monthly income until move
reservetotal s0                      25000  2015-09-01 2015-10-01 reserve  Initial=.1 [ RInvest=. 1                                       stock value at model start
reservetotal s0                      130000 2015-09-01 2015-10-01 reserve  Initial=.1                                                     savings at model start
salary       s0                      4200   2016-08-01 2023-07-01 history  BackPeriods=.4 [ YearInflate=.1.5                              reduced net income after move until retirement
house        s0          move        2000   2016-08-01 2016-09-01 history                                                                 moving expenses
house        s0                      100    2016-08-01 2044-01-01 history                                                                 incidental housing expenses after move
house        s0                      100    2016-08-01 2044-01-01 history                                                                 home owners association payments
house        s0                      150    2016-08-01 2044-01-01 history                                                                 property taxes
reservetotal s0          buy house   110000 2016-08-01 2016-09-01 reserve  Initial=.1 [ REquity=. 1                                       down payment added to house equity initial setting prevents double spend
loan         s0          buy house   150000 2016-08-01 2023-02-01 borrow   Interest=. 4.5 [ YearTerm=. 30 [ DHouse=.1  [ LoanEquity=.1    30 year mortgage rate on house until inheritance
reservetotal s0          buy house   110000 2016-08-01 2016-09-01 spend                                                                   down payment on house from savings
annuities    s0                      250    2018-07-01 2035-08-01 history                                                                 monthly retirement and other annuity payments end date is unknown
annuities    s0                      50     2018-07-01 2035-08-01 history                                                                 any government pension payments
reservetotal s0          assumptions 0      2020-01-01 2044-01-01 assume   RSavings=. -2.5 [ RInvest=. -5.0 [ REquity=. -5.0 [ ROther=. 2 market tanks government introduces negative interest
loan         s0          buy car     10000  2020-07-01 2025-07-01 borrow   Interest=. 5 [ YearTerm=. 5 [ DCar=.1                          pay balance of car at 5% for 5 years
reservetotal s0          buy car     7000   2020-07-01 2020-08-01 spend                                                                   car down payment from savings
reservetotal s0          inherit     180000 2023-01-01 2023-02-01 reserve  Initial=.1                                                     inheritance to savings
reservetotal s0          buy house   150000 2023-03-01 2023-04-01 transfer Fee=. 1500 [ DHouse=.1                                         pay off remaining mortgage balance after inheritance fee is closing cost
salary       s0                      1400   2023-07-01 2035-08-01 history                                                                 estimated social security payments spread over expected life
insurance    s0                      700    2023-07-01 2024-12-01 history                                                                 medical insurance in the gap between retirement and spouse medicare eligibility
annuities    s0                      100    2024-12-01 2044-01-01 history                                                                 any retirement pension payments to spouse
annuities    s0                      100    2035-08-01 2044-01-01 history                                                                 any us social security survivor benefit after first death

Again the first header row is a simple list of names. Most scenario names are self-explanatory but four OnDate, OffDate, Method, and MethodArguments merit some explanation. SWAG series methods assume, history, reserve, transfer, borrow, and spend are modeled on what people typically do with cash.

1. assume sets expected interest rates and other global assumptions for a given time period. SWAG series methods operate over a well-defined time period. The period is defined by OnDate and OffDate.
2. history looks at past periods and estimates a numeric value that is projected into the future. Currently, history computes simple means but the underlying code can use arbitrary time series verbs.
3. reserve manages savings, investments, equity and other cash-like instruments.
4. borrow borrows money and sets future loan payments. borrow supports simple amortization loans but is also capable of reading an arbitrary payment schedule that can be used for exotic2 loans.
5. transfer moves money between reserves, debts, expenses and income series.
6. spend does just what you expect.

SWAG series methods adjust all the series affected by the method. As you might expect SWAG arguments methods are detailed. MethodArguments uses a restricted J syntax to set SWAG arguments. Argument order does not matter but only supported names are allowed. Many examples of SWAG MethodArguments can be found in the EXCEL spreadsheet tp.xlsx. I use EXCEL as a scenario editor. By setting EXCEL filters, you can manage many scenarios.

The final SWAG input is a name cross-reference table. It is another TAB delimited text file that defines SWAG names. You can inspect a typical cross-reference table here.

## Running SWAG

To run SWAG you:

1. Prepare input files.
2. Start J, any front-end jconsole, JQT or JHS will do, and load the Swag script.
3. Execute RunTheNumbers.
4. Open the EXCEL spreadsheet swag.xlsx, click on the data ribbon and then press the “Refresh All” button.

Let’s work through the steps.

## Prepare Input Files

By far the most difficult step is the first. Here you review your financial status which means checking bank balances, stock values, loan balances and so on. Depending on your holdings this could take anywhere from minutes to hours. I call this updating actuals. Not only is updating actuals the most difficult and time-consuming step it is also the most valuable. Money that is not closely watched leaks away.

I store my actuals in a simple tabbed spreadsheet. Each tab maintains an image of a text file. I enter my data and then cut and paste the sheets into a text editor where I apply final tweaks and then save the sheets as TAB delimited text files.

Monthly income, expenses and debts are easy to update but some of my holdings do not offer monthly statements. The verb RawReservesFromLast in Swag.ijs fills in missing months with the last known values. When I’m finished preparing input files I’m left with four actual TAB delimited files, RawIncome.txt, RawExpenses.txt, RawReserves.txt, and RawDebts.txt. You can inspect example actual files here.

## Start J and load the Swag script.

The SWAG script is relatively self-contained. It can be run in any J session that loads the standard J profile. Load Swag with the standard load utility.

Here SWAG is loaded in JHS.

Execute RunTheNumbers

RunTheNumbers sets the SWAG configuration, loads scenarios, copies actuals to each scenario, and then evaluates each scenario. Scenarios are numbered. I use positive numbers for “production” scenarios and negative numbers for test scenarios. It sounds more complicated that it is. This is all you have to do to execute RunTheNumbers

RunTheNumbers 0 1 2 3 4

The code is simple and shows what’s going on.

RunTheNumbers=:3 : 0

NB.*RunTheNumbers v-- compute all scenarios on list (y).
NB.
NB. monad:  blclFiles =. RunTheNumbers ilScenarios
NB.
NB.   RunTheNumbers 0 1 2 3 4

NB. parameters sheet is the last config sheet
ModelConfiguration_Swag_=:MainConfiguration_Swag_
scfx=. ScenarioPrefix

ac=. toHOST fmttd ActualSheet 0
ac write TABSheetPath,'MainActuals',SheetExt

sf=. 0\$a:
for_sn. y do.
ac write TABSheetPath,scfx,(":sn),'Actuals',SheetExt
sf=. sf , parms Swag sn [ LoadSheets sn
end.

sf
)

RunTheNumbers writes a pair of TAB delimited forecast and statistics files for each scenario it evaluates.

Open swag.xlsx and press “Refresh All”

The spreadsheet swag.xlsx loads SWAG TAB delimited text files and plots results.3 I plot monthly cash flow, estimated net worth and debt/equity for each scenario. The following is a typical cash flow plot. It estimates mean monthly cash balance over the scenario time range.

The polynomial displayed on the graph is an estimated trend line. Things are looking bleak.

Here’s a typical net worth plot.

In this happy scenario, we die broke and leave a giant bill for the government.4

So far SWAG has met my basic needs and forced me to pay more attention to the proverbial bottom line. As I use the system I will fix bugs, refine rough spots, and add strictly necessary features. Feel free to use or modify SWAG for your own purposes. If you find SWAG useful please leave a note on this blog or follow the SWAG repository on GitHub.

1. What do you call dis-integrated collections of programs that you use to solve problems? Declaring such dog piles “systems” demeans the word “system” and gives the impression that everything has been planned. This is not how I roll. “Mob” is far more appropriate. It conveys a proper sense of disorder and danger.
2. When borrowing money you should always plan on paying it all back. Insist on a complete iron clad repayment schedule. If such a schedule cannot be provided run like hell or prepare for the thick end of a baseball bat to be rammed up your financial ass.
3. It may be necessary to adjust file paths on the EXCEL DATA ribbon to load SWAG TAB delimited text files.
4. They can see me in Hell to collect.

# Turning JOD Dump Script Tricks

Have you ever wondered how extremely prolific bloggers do it? How is it possible to crank out thousands of blog entries per year without creating a giant stinking pile of mediocre doo-doo? Like most deep medium mysteries it’s not very deep and there are no mysteries. The spewers, people who post like teenage girls tweet, use two basic strategies:

1. Multiple authors: The heroic image of the lone blogger waging holy war against a sea of Internet idiocy is largely a myth. Many popular prolific blogs are the work of many hands. The editor at Analyze the Data not the Drivel eschews this tactic. Apparently he’s an incontinent and argumentative prima donna that sane people steer clear of.
2. Content recycling: In elementary school this was called copying. Now that we’re all grown up we use terms like, “excerpting”, “abstracting”, and my favorite “re-purposing.” The basic idea is simple. Take something you’ve written elsewhere and repackage it as something new. Hey, all the cool kids are doing it!

The following is a slightly edited new appendix I have just added to the JOD manual. I am working to properly publish the JOD manual mostly so I can say that I’ve written a legitimate, albeit strange and queer, book.

I created this post by running the $\LaTeX$ code of the manual appendix through the excellent utility pandoc, tweaking the resulting markdown, and then using pandoc again to generate html for this blog. pandoc is a great “re-purposing” tool!

Finally, re-purposing is not entirely cynical. The act of moving material from one medium to another exposes problems. I found a few editing errors while creating this post that eluded my $\LaTeX$ eyes. If you find more this is your chance to tell me what a moron I am.

# Turning JOD Dump Script Tricks

Dump script generation is my favorite JOD feature. Dump scripts serialize JOD dictionaries; they are mainly used to back up dictionaries and interact with version control systems. However, dump scripts are general J scripts and can do much more! Maintaining a stable of healthy JOD dictionaries is easier if you can turn a few dump script tricks.1

1. Flattening reference paths: Open JOD dictionaries define a reference path. For example, if you open the following dictionaries:
NB. open four dictionaries
od ;:'smugdev smug image utils'
+-+-----------------------+-------+----+-----+-----+
|1|opened (ro/ro/ro/ro) ->|smugdev|smug|image|utils|
+-+-----------------------+-------+----+-----+-----+

the reference path is /smugdev/smug/image/utils.

When objects are retrieved each dictionary on the path is searched in reference path order. If there are no compelling reasons to maintain separate dictionaries you can improve JOD retrieval performance and simplify dictionary maintenance by flattening all or part of the path.

To flatten the reference path do:

NB. reopen the first three dictionaries on the path
od ;:'smugdev smug image' [ 3 od ''
+-+--------------------+-------+----+-----+
|1|opened (ro/ro/ro) ->|smugdev|smug|image|
+-+--------------------+-------+----+-----+

NB. dump to a temporary file (df)
df=: {: showpass make jpath '~jodtemp/smugflat.ijs'
+-+---------------------------+-----------------------+
|1|object(s) on path dumped ->|c:/jodtemp/smugflat.ijs|
+-+---------------------------+-----------------------+

NB. create a new flat dictionary
newd 'smugflat';jpath '~jodtemp/smugflat' [ 3 od ''
+-+---------------------+--------+--------------------+
|1|dictionary created ->|smugflat|c:/jodtemp/smugflat/|
+-+---------------------+--------+--------------------+

NB. open the flat dictionary and (utils)
od ;:'smugflat utils'
+-+-----------------+--------+-----+
|1|opened (rw/ro) ->|smugflat|utils|
+-+-----------------+--------+-----+

NB. reload dump script ... output not shown ...
0!:0 df

The collapsed path /smugflat/utils will return the same objects as the longer path. It is important to understand that the collapsed dictionary smugflat does not necessarily contain the same objects found in the three original dictionaries smugdev, smug and image. If objects with the same name exist in the original dictionaries only the first one found will be in the collapsed dictionary.

2. Merging dictionaries: If two dictionaries contain no overlapping objects it might make sense to merge them. This is easily achieved with dump scripts. To merge two or more dictionaries do:
NB. open and dump first dictionary
od 'dict0' [ 3 od ''
+-+--------------+-----+
|1|opened (rw) ->|dict0|
+-+--------------+-----+
df0=: {: showpass make jpath '~jodtemp/dict0.ijs'
+-+---------------------------+--------------------+
|1|object(s) on path dumped ->|c:/jodtemp/dict0.ijs|
+-+---------------------------+--------------------+

NB. open and dump second dictionary
od 'dict1' [ 3 od ''
+-+--------------+-----+
|1|opened (rw) ->|dict1|
+-+--------------+-----+
df1=: {: showpass make jpath '~jodtemp/dict1.ijs'
+-+---------------------------+--------------------+
|1|object(s) on path dumped ->|c:/jodtemp/dict1.ijs|
+-+---------------------------+--------------------+

NB. create new merge dictionary
newd 'mergedict';jpath '~jodtemp/mergedict' [ 3 od ''
+-+---------------------+---------+---------------------+
|1|dictionary created ->|mergedict|c:/jodtemp/mergedict/|
+-+---------------------+---------+---------------------+

NB. open merge dictionary and run dump scripts
od 'mergedict'
+-+--------------+---------+
|1|opened (rw) ->|mergedict|
+-+--------------+---------+

NB. reload dump scripts ... output not shown ...
0!:0 df0
0!:0 df1

Be careful when merging dictionaries. If there are common objects the last object loaded is the one retained in the merged dictionary.

3. Updating master file parameters: When a new parameter is added to jodparms.ijs it will not be available in existing dictionaries. With dump scripts you can rebuild existing dictionaries and update parameters. To rebuild a dictionary with new or custom parameters do:
NB. save current dictionary registrations
(toHOST ; 1 { 5 od '') write_ajod_ jpath '~temp/jodregister.ijs'

NB. open dictionary requiring parameter update
od 'dict0' [ 3 od ''
+-+--------------+-----+
|1|opened (rw) ->|dict0|
+-+--------------+-----+

NB. dump dictionary and close
df=: {: showpass make jpath '~jodtemp/dict0.ijs'
+-+---------------------------+--------------------+
|1|object(s) on path dumped ->|c:/jodtemp/dict0.ijs|
+-+---------------------------+--------------------+

3 od ''
+-+---------+-----+
|1|closed ->|dict0|
+-+---------+-----+

NB. erase master file and JOD object id file
1
1

NB. recycle JOD - this recreates (jmaster.ijf) and (jod.ijn)
NB. using the new dictionary parameters defined in (jodparms.ijs)
(jodon , jodoff) 1
1 1

NB. re-register dictionaries

NB. create a new dictionary - it will have the new parameters
newd 'dict0new';jpath '~jodtemp/dict0new' [ 3 od ''
+-+---------------------+---------+-------------------+
|1|dictionary created ->|dict0new|c:/jodtemp/dict0new/|
+-+---------------------+---------+-------------------+

od 'dict0new'
+-+--------------+--------+
|1|opened (rw) ->|dict0new|
+-+--------------+--------+

NB. reload dump script ... output not shown ...
0!:0 df

Before executing complex dump script procedures back up your JOD dictionary folders and play with dump scripts on test dictionaries. Dump scripts are essential JOD dictionary maintenance tools but like most powerful tools they must be used with care.

1. Spicing up one’s rhetoric with a double entendre like “turning tricks” may be construed as a microaggression. The point of colored language is to memorably make a point. You are unlikely to forget turning dump script tricks.

# JOD Update: Version 0.9.97*

In the last year much has changed in the J world.

1. There are new official J 8.0x builds for all supported platforms.
2. The QT based IDE JDE has matured and is in widespread use.
3. The column oriented J database JD is drawing new users to J and enticing J veterans to reconsider how we use databases.
4. There is a small group of J system builders experimenting with additions, extensions and revisions of core J source code.

In short, there are have been enough changes to revisit and update JOD.

JOD version 0.9.97*1 is the first JOD update in many years that mocks the god of software compatibility. In particular:

1. The syntax of the jodhelp verb has changed.
2. The jodsource addon no longer uses a zip file to distribute JOD dump files.
4. Volume size is no longer checked before creating new JOD dictionaries.
5. There is a new version of jod.pdf.

#### jodhelp changes (#1, #3 and #5)

jodhelp has always been a kludge. In programmer speak a kludge is some half-baked facility added to a system after more essential features have stabilized. The original versions of jodhelp pointed at my rough notes. It was all the “documentation” I needed! Then others stared using JOD which resulted in an “evolved” online version of my notes. I originally thought that hosting my notes online would simultaneously serve user needs and cut the amount of time I spent maintaining documentation. In retrospect this wasn’t even wrong!

I used Google Documents to host my notes. If you’ve ever wondered why completely free Google Documents hasn’t obliterated expensive Microsoft Word or hoary old excellent $\LaTeX$ I invite you to maintain a set of long-duration-documents with Google Documents. During jodhelp‘s online lifetime the basic internal format of Google Documents changed in a screw-your-old-documents upgrade which forced me to spend days repairing broken hyper-links and reformatting. I was not amused; you still get what you pay for!

I originally choose Google Documents because of its alleged global accessibility. Sadly, Google Documents is now often blocked by corporate and national firewalls. Even when it isn’t blocked it renders like a dog peeing on a fire hydrant. All these problems forced me to rewrite JOD documentation with a completely reliable tool: good old-fashioned $\LaTeX$. The result of my labors, jod.pdf, is now distributed by the joddocument addon and is easily browsed with jodhelp.

After jod.pdf‘s appearance another irritant surfaced: synchronizing jod.pdf and the online version. I tried using pandoc and markdown to generate both the online and PDF versions from the same source files but jod.pdf is too complex for not-to-fancy portable approaches. I was faced with a choice, lower my jod.pdf standards, or get rid of something I never really liked. I opted to drown a child and abandon online help. I don’t expect a lot of mourners at the funeral.

Using the new version of jodhelp requires installing the addon joddocument and configuring a J PDF reader. It’s also good idea to define a JQT PF key to pop up JOD help with a keystroke. To configure a J PDF reader edit the configuration file:

~config/base.cfg

this file is directly available from the JQT Edit\Configure menu. base.cfg defines a number of operating system dependent utilities. Make changes to the systems you use, save your changes, and restart J. The following example shows my Win64 system settings.

case. 'Win' do.
BoxForm=: 1
Browser_nox=: ''
XDiff=: 'c:/uap/WinMerge-2.14.0-exe/winmergeu.exe'
Editor_nox=: ''

I use SumatraPDF to read PDF files on Windows. It’s a fast, lightweight, program that efficiently renders jod.pdf. Good PDF readers are available for all commonly used platforms.

To define JQT PK keys edit the configuration file:2

~config/userkeys.cfg

This file is also directly available from Edit\Configure menu. My JOD specific PF keys are:

F3;1;Require JOD;require 'general/jod'
Shift+F3;1;JOD Help;jodhelp 0
F6;1;Dev Dicts;od cut 'joddev jod utils' [ 3 od ''
Shift+F6;1;Fit Dev Dicts;od cut 'jodfit joddev jod utils' [ 3 od ''
Ctrl+Shift+F6;1;Test Dev Dicts;od cut 'jodtest joddev jod utils' [ 3 od ''

Pressing Shift+F3 executes jodhelp 0 which pops up JOD help.

#### jodsource changes (#2)

The jodsource addon is a collection of JOD dump scripts. Dump scripts are serialized versions of binary JOD dictionaries. When executed they merge objects into the current JOD put dictionary. I use them primarily to move dictionaries around but they have other uses as well. Prior to this version I distributed the three main JOD development dump scripts, joddev, jod, and utils in one compressed zip file to reduce the size of JAL downloads.

The distributed script jodsourcesetup.ijs used the zfiles addon to extract these scripts and rebuild JOD development dictionaries. This worked on 32 bit Windows systems but failed elsewhere. J now runs on 32/64 bit Windows, Mac, Linux, IOS and Android systems. To better support all these variants I eliminated the zfiles dependency and pruned the JOD development dictionaries. The result is a more portable and smaller jodsource addon.

#### Bye bye volume sizing (#4)

Early versions of JOD ran in the now bygone era of floppy disks. It was possible to create many JOD dictionaries on a single standard 800 kilobyte 3.5 inch floppy. Compared to modern porcine-ware JOD, which many J’ers consider a huge system, is lithe and lean. In floppy days it was important to check if there was enough space on a floppy before creating another huge 48K empty JOD dictionary. This is a bit ridiculous today! If you don’t have 48K free on whatever device you are running you have far more serious problems than not being able to create JOD dictionaries.

Volume sizing code remained in JOD for years until it started giving me problems. Returning the size of very large network volumes can be time-consuming and there are serious portability issues. Every operating system calls different facilities to return volume sizes. Even worse, security settings on corporate networks and cloud architectures sometimes refuse to divulge national secrets like free byte counts.

To eliminate all these headaches this version of JOD no longer checks volume size when the FREESPACE noun is zero. To restore the previous behavior you have to edit the file

and change the line FREESPACE=:0 to whatever byte count you want. Alternatively, you could NGAF3 and just assume you have 48K free on your terabyte size volumes.

#### Still to come

You may have surmised from JOD’s version number that the system is still not feature complete.  The JOD manual lists a few words that I am planning to implement. I only develop JOD when I need something or I am bored out of my mind at work and need a break. Such intermittent motivators seldom insure project completion but I have found a new reason to finish JOD. To list a book on Goodreads or Amazon you need an ISBN number.  The hardcopy version of the JOD manual is a sort-of-published book. To complete the publishing process I need an ISBN. If I am going to bother with such formalities I might as well complete the system the manual describes. So there you have it a new software development motivator: vanity.

1. The version number is *‘ed because you are always a point release from done!
2. userkeys.cfg is only available for J 8.03 systems.
3. Not Give a F%&k!

# JOD Update: J 8.02 QT/JHS/64 bit Systems

I have pushed out a JOD update that makes it possible to run the addon on J 8.02 systems. In the last eight months a QT based J IDE has been developed that runs on Linux, Windows and Mac platforms. To maintain JOD’s compatibility across all versions of J from 6.02 on I had to tweak a few verbs.

The only significant changes are how JOD interacts with various J system editors.  I have tested the system on Windows  J 6.02, J 7.01, J 8.02, and Mac J 7.01 systems. I expect it will behave on 32 and 64 bit Linux systems from J 7.01 on, but I have yet to test these setups. My hardware budget limits my ability to run common variants of Windows, Linux and Mac systems.

JOD is still not complete; that’s why the version number has not been bumped past 1.0.0. The missing features are noted in the table of contents of jod.pdf, (also available in the joddocument addon), with the suffix “NIMP,” which means “not implemented.”  I will fill in these blanks as I need them. Most of the time JOD meets my needs so don’t hold your breath.

If you want to make your own additions to JOD the program and documentation source is available on GitHub. Just follow the links and enjoy.

As a last note: I will be at the J Conference in Toronto (July 24 and 25, 2014) where I will be giving a short presentation and handing out a few hardcopy versions of the JOD manual to one or two JOD fans.

# Mac JOD

JOD now runs on the Mac

The J addon JOD now runs on Macs. You can update JOD, or install it for the first time, with JAL. JOD now runs on all the major J hosts: Windows, Linux and the Mac.

To keep track of host specific features I have started a series of version documents. The Mac document is here.

At the upcoming J conference, (July 23-24, 2012), in Toronto I will show an iPhone version of JOD. And, as a reward for attending the conference and my little presentation, Writing Portable J addons, I will be raffling off hardcopy printed versions of the JOD manual.

An updated PDF version of the JOD manual is available here. For more see The JOD Page.

# JOD comes to Linux

For years I have distributed a J Addon called JOD. JOD stands for J Object Dictionary. JOD is a code database for the J programming language. Instead of storing my J programs in text files, like every other programmer in the world, I break them down into the smallest reusable units. In J parlance I split my scripts into words.

If you are an experienced programmer I wouldn’t blame you for questioning my sanity. What could possibly be gained by discounting good old-fashioned, superbly supported, ASCII/UTF8 text files? The short answer, in trendy software engineer speak, is refactoring. JOD is a refactoring engine that works at the J word level.

What does the word level mean? Program text files are collections of many “words.” They roughly correspond to sentences, paragraphs, sections and chapters in ordinary books. When you reuse, or quote, a book you typically copy passages and paste them into new contexts. Programmers call this cut and paste programming. We have all cut and pasted; it’s a software sin our prophets are constantly nagging us about! JOD minimizes cut and paste programming. You no longer cut and paste or include you simply get lists of words. J words are closer to English words than you might expect: hence this dictionary approach pays big dividends!

With the release of J 7.01 it’s become clear that Windows is no longer the preeminent J platform. The new JGTK interface works well on Windows but it sings on Linux. This is hardly surprising. GTK originated in the Linux/Unix world and still performs best there. Porting JOD to Linux has been on my to-do list for years. The arrival of J 7.01 got me off my butt.

JOD 0.9.3 is the first publicized Linux release. JOD code is 99% J and makes limited use of OS facilities. The port consisted of finding Linux equivalents for a handful of Windows API calls. The always helpful J community provided useful pointers. Joey Tuttle and Bill Lam basically solved my Linux GUID and file handling problems. Thanks guys.

My biggest chore was updating JOD online documentation. In recent months Google Documents changed the format of their word processing documents. Google provided an upgrade tool to convert old documents to the new format but it:

1. Did not remap scores of old URLs to new URLs. I had to go through every document doing this one link at a time!
2. Totally wrecked a few documents. I reconstructed JOD Release Notes from version control logs.

Despite these irritants the new format is better. You can attach comments and download documents in ODT, PDF, Word, HTML and ZIP formats. If you find problems with my documents please leave notes.

I am not completely satisfied with some restrictions imposed by JOD 0.9.3.

1. JOD creates dictionaries in user home directories like /home/user/jod/… and assumes it has the rights to create, write, copy and erase JOD files and directories.
2. No blanks in file paths, i.e., /home/i like blanks/but jod doesnt/.. will not work.
3. Dictionary paths must begin with a forward slash, i.e., /home/is/ok/ but ~is/not/allowed/
4. Volume sizing reports the smallest amount of free space on all mounted volumes and not the free space on the volume containing JOD directories. I just don’t know how to do this on Linux.
5. jod.pdf has not been updated.

I am sure there are other problems and limitations that I have missed. For more see: Linux Notes. I will be releasing fixes and upgrades via JAL and on the JOD page. Give JOD a whirl. It might change your J ways.