I wrote my first literate program in November of 2015. Since then, I've been writing literate programs on an almost daily basis. It has been an experience with a sort of enlightenment that I haven't had in a long time. Not only is it a lot of fun to write literate programs, I feel like I have gained a new "super power" of sorts.
Below are my thoughts on my experiences with literate programming so far.
| Project name | Lines of code | Words in literate document | Ratio of words to lines |
|---|---|---|---|
| Token Cleaner | 46 | 496 | 10.782609 |
| Okta Sign-In Widget | 120 | 3862 | 32.183333 |
| Okta SCIM Beta | 360 | 7966 | 22.127778 |
| Dial-a-cat | 370 | 3620 | 9.7837838 |
| Okta OIDC Beta | 752 | 7731 | 10.280585 |
Explanation:
- Lines of code is the number of lines of "code" generated by
the literate program. "code" is in quotes because the code is
anything in an Org Babel "source" block, it could be Python,
Shell, HTML, etc. This number comes from running this command on
an Org Babel file:
awk '/BEGIN_SRC/,/END_SRC/' $filename - Words in document per lines of code is the number of words in a
file, note that in includes the source code as well. This number
comes from running this command on an Org Babel file:
wc -w - Ratio of words to lines is: Words in literate document divided by Lines of code
I feel hobbled by in-line code comments now. One of the clearest benefits of literate programming is being able to weave my code into large sections of prose, instead of interleaving small sections of prose into code.
Now I find myself spending time to add in detailed references an
explanations with my code. One example of this is including a
curl command, links to RFCs, and a note about "1-indexed" versus
"0-indexed" differences in the "Resource Paging" section of my
Okta SCIM Beta document. Another example is being able to cover a
function line-by-line, as well as include unit tests in-line in
the "Validating an OIDC id_token from Okta" section of my
Okta OIDC Beta document.
Take a look at the table listed in the "Dependencies" section of
the Okta SCIM Beta document. Then take a look at the
requirements.txt file in the same repository. The dependencies
table and the requirements.txt file are both generated from a
single table in Org Babel!
This is all made possible by the ability to write in-line code to generate the requirements.txt file and code to generate the table markdown for GitHub Pages.
In the Okta SCIM Beta document, I am able define a copyright notice in one place and have that copyright notice written to a LICENSE.txt file and have the same notice included into the scim-server.py file.
When I was writing the Okta OIDC Beta document, I spent a lot of
time finding the arcane openssl incantations needed to generate
x509 certificates that I needed for a unit test. Because I was
writing a literate document, I was able to include all of the
commands that I used, along with a detailed explanation of what
each command did.
Being able to execute these commands and see their output without needing to switch to a terminal made it really easy to interactively explore the commands that I needed to generate the certificates, and to keep track of those commands for the next time that I need to generate similar certificates or keys.
Since Org Babel is part of Org Mode, it is trivial to make use of Org's time tracking and project planning features.
I usually keep track of my time in my usual Org setup, but when appropriate it's nice to be able to keep track of my time inside the same literate document that I'm working on.
You can see an example of time tracking and project planning in
the dial-a-cat document. (Look for the lines with CLOCK, DONE,
or TODO.
Being able to keep code and prose synchronized is a problem that I first encountered when I was writing blog posts for Twilio, searching for this "holy grail" is what first got me interested in literate programming. What I wanted was a tool that could generate Markdown and code from the same file, which is exactly what Org Babel can do.
I was sold on Org Babel after I converted my favorite blog post on the Twilio blog to a literate document, and found an inconsistency in the process.
Now, because I know that my code and prose will always be consistent, I find myself making quick changes to code that I wouldn't have made otherwise.
Now that I have a tool which makes it easy to write an "essay" about my code, I'm faced with new questions that I never had the luxury of considering before.
I imagine that satisfactorily answering the question "how can I describe this code best?" is a lifelong endeavor.
Here are the specific questions that I find myself facing at this moment:
Once a section of code is embedded in prose, it becomes a lot harder to change that code.
Because of this, I find that the best way to write a literate program is to start with the code first and wait to turn the code into a literate document after extensive refactoring.
Describing a short program can be as easy as describing the program from "top to bottom", as I do in my token cleaner project.
However, as a project grows, I'm finding that the structure I used to describe a small project will change when it becomes a medium sized project, and change again when it becomes a large project.
Another thing that I've been struggling with is figuring out the right balance between describing a program line-by-line, or skipping large sections of code entirely. I feel like the ideal method will lean more towards the "line-by-line" approach, but I think I need more hands on experience in this area.
Literate programming has been a very worthwhile discipline to learn, I still have a lot of things to learn, and I look forward to getting better at writing literate programs in the decades ahead.
I'd love to hear and feedback that you have on this document. Please reach out to me on Twitter!
- Joël Franusic, May 2016