187 lines
6.7 KiB
Markdown
187 lines
6.7 KiB
Markdown
# Fermi: A terminal DSL for Fermi estimation with distributions
|
|
|
|
This project is a minimalist, calculator-style DSL for fermi estimation. It can multiply, divide, add and subtract scalars, lognormals and beta distributions, and supports variables and mixtures.
|
|
|
|
## Usage
|
|
|
|
```
|
|
$ fermi
|
|
5M 12M # number of people living in Chicago
|
|
beta 1 200 # fraction of people that have a piano
|
|
30 180 # minutes it takes to tune a piano, including travel time
|
|
/ 48 52 # weeks a year that piano tuners work for
|
|
/ 5 6 # days a week in which piano tuners work
|
|
/ 6 8 # hours a day in which piano tuners work
|
|
/ 60 # minutes to an hour
|
|
=: piano_tuners
|
|
```
|
|
|
|
Here are some real-life examples: [Chance for a Russian male of fighting age of being drafted](https://x.com/NunoSempere/status/1829525844169248912), [did the startup Friend burn too much cash](https://x.com/NunoSempere/status/1818810770932568308), [how much did Nikita Bier make mentoring?](https://x.com/NunoSempere/status/1815169781907042504), [what fraction of North Korea's caloric intake is Russia supporting?](https://x.com/NunoSempere/status/1855666428835140078). In general, as a terminal guy, I've found that having zero startup cost makes creating small fermi models much cheaper, and thus happen more often.
|
|
|
|
## Build instructions
|
|
|
|
Install the [go toolchain](https://go.dev/dl/), then:
|
|
|
|
```
|
|
git clone https://git.nunosempere.com/NunoSempere/fermi
|
|
cd fermi
|
|
make build
|
|
./fermi
|
|
# sudo make install
|
|
# fermi
|
|
```
|
|
|
|
|
|
## Tips & tricks
|
|
|
|
- It's conceptually clearer to have all the multiplications first and then all the divisions
|
|
- For distributions between 0 and 1, consider using a beta distribution
|
|
- The default operation is multiplication
|
|
|
|
If you type "help" (or run fermi -h), you can see a small grammar and some optional command flags:
|
|
|
|
```
|
|
$ fermi -h
|
|
|
|
1. Grammar:
|
|
Operation | Variable assignment | Special
|
|
Operation: operator operand
|
|
operator: (empty) | * | / | + | -
|
|
operand: scalar | lognormal | beta | variable
|
|
lognormal: low high
|
|
beta: beta alpha beta
|
|
Variable assignment: =: variable_name
|
|
Variable assignment and clear stack: =. variable_name
|
|
Special commands:
|
|
Comment: # this is a comment
|
|
Summary stats: stats
|
|
Clear stack: clear | c | .
|
|
Print debug info: debug | d
|
|
Print help message: help | h
|
|
Start additional stack: operator (
|
|
Return from additional stack )
|
|
Exit: exit | e
|
|
Examples:
|
|
+ 2
|
|
/ 2.5
|
|
* 1 10 (interpreted as lognormal)
|
|
+ 1 10
|
|
* beta 1 10
|
|
1 10 (multiplication taken as default operation)
|
|
=: x
|
|
.
|
|
1 100
|
|
+ x
|
|
# this is a comment
|
|
* 1 12 # this is an operation followed by a comment
|
|
* (
|
|
1 10
|
|
+ beta 1 100
|
|
)
|
|
/ 1%
|
|
=. y
|
|
mx x 1 y 2.33
|
|
+ mx x 30% y 70%
|
|
exit
|
|
|
|
2. Command flags:
|
|
-echo
|
|
Specifies whether inputs should be echoed back. Useful if reading from a file
|
|
. -f string
|
|
Specifies a file with a model to run
|
|
-n int
|
|
Specifies the number of samples to draw when using samples (default 100000)
|
|
-h Shows help message
|
|
|
|
```
|
|
|
|
### Integrations with Linux utilities
|
|
|
|
Because the model reads from standard input, you can pipe a model to it:
|
|
|
|
```
|
|
$ cat more/piano-tuners.fermi | fermi
|
|
```
|
|
|
|
In that case, you will probably want to use the echo flag as well
|
|
|
|
```
|
|
$ cat more/piano-tuners-commented.fermi | fermi -echo
|
|
```
|
|
|
|
You can make a model an executable file by running `$ chmod -x model.fermi` and then adding the following at the top, XD.
|
|
|
|
```
|
|
#!/bin/usr/fermi -f
|
|
```
|
|
|
|
You can save a session to a logfile with tee:
|
|
|
|
```
|
|
fermi | tee -a fermi.log
|
|
```
|
|
|
|
## Different levels of complexity
|
|
|
|
The mainline code has a bunch of complexity: variables, parenthesis, samples, beta distributions, number of samples, mixtures etc. In the simple/ folder:
|
|
|
|
- f_simple.go (370 lines) strips variables and parenthesis, but keeps beta distributions, samples, and addition and subtraction
|
|
- f_minimal.go (140 lines) strips everything that isn't lognormal and scalar multiplication and addition, plus a few debug options.
|
|
|
|
## Roadmap
|
|
|
|
Done:
|
|
|
|
- [x] Write README
|
|
- [x] Add division?
|
|
- [x] Read from file?
|
|
- [x] Save to file?
|
|
- [x] Allow comments?
|
|
- [x] Use a sed filter?
|
|
- [x] Add proper comment processing
|
|
- [x] Add show more info version
|
|
- [x] Scalar multiplication and division
|
|
- [x] Think how to integrate with squiggle.c to draw samples
|
|
- [x] Copy the time to botec go code
|
|
- [x] Define samplers
|
|
- [x] Call those samplers when operating on distributions that can't be operated on algebraically
|
|
- [x] Display output more nicely, with K/M/B/T
|
|
- [x] Consider the following: make this into a stack-based DSL, with:
|
|
- [x] Variables that can be saved to and then displayed
|
|
- [x] Other types of distributions, particularly beta distributions? => But then this requires moving to bags of samples. It could still be ~instantaneous though.
|
|
- [x] Added bags of samples to support addition and multiplication of betas and lognormals
|
|
- [x] Figure out go syntax for
|
|
- Maps
|
|
- Joint types
|
|
- Enums
|
|
- [x] Fix correlation problem, by spinning up a new randomness thing every time some serial computation is done.
|
|
- [x] Clean up error code. Right now only needed for division
|
|
- [x] Maintain *both* a more complex thing that's more featureful *and* the more simple multiplication of lognormals thing.
|
|
- [x] Allow input with K/M/T
|
|
- [x] Document parenthesis syntax
|
|
- [x] Specify number of samples as a command line option
|
|
- [x] Figure out how to make models executable, by adding a #!/bin/bash-style command at the top?
|
|
- [x] Make -n flag work
|
|
- [x] Add flag to repeat input lines (useful when reading from files)
|
|
- [x] Add percentages
|
|
- [x] Consider adding an understanding of percentages
|
|
- [x] Improve and rationalize error messages a bit
|
|
- [x] Add, then document mixture distributions
|
|
|
|
To (possibly) do:
|
|
|
|
- [ ] Consider implications of sampling strategy for operating variables.
|
|
- [ ] Fix lognormal multiplication and division by 0 or < 0
|
|
- [ ] With the -f command line option, the program doesn't read from stdin after finishing reading the file
|
|
- [ ] Add functions. Now easier to do with an explicit representation of the stack
|
|
- [ ] Think about how to draw a histogram from samples
|
|
- [ ] Dump samples to file
|
|
- [ ] Represent samples/statistics in some other way
|
|
- [ ] Perhaps use qsort rather than full sorting
|
|
- [ ] Program into a small device, like a calculator?
|
|
- [ ] Units?
|
|
|
|
Discarded:
|
|
|
|
- [ ] ~~Think of some way of calling bc~~
|