Diesel

Language

Schedule model

Diesel's model of a schedule is an aggregate of events where each occurrence of an event is determined by its predicate - a mapping from a date to either true or false, true meaning the event occurs on that date.

Examples

Parenting schedule

Parent 1:

(date >= 2023-12-03) & (
  (
      (nw(2023-12-03, date) % 2 = 0)
        & ((wd = sun) | (wd = mon) | (wd = thu) | (wd = fri) | (wd = sat))
  )
  | (
      (nw(2023-12-3, date) % 2 = 1)
        & ((wd = tue) | (wd = wed))
  )
)

Parent 2:

(date >= 2023-12-03) & (
  (
      (nw(2023-12-03, date) % 2 = 0)
        & !((wd = sun) | (wd = mon) | (wd = thu) | (wd = fri) | (wd = sat))
  )
  | (
      (nw(2023-12-3, date) % 2 = 1)
        & !((wd = tue) | (wd = wed))
  )
)

Result:

Cheat sheet

Placeholder units

For a predicate to be evaluated, it must be given some context - a date. There are 5 placeholder units that can show up in a predicate, such that on evaluation they are subsituted with their value from the given context:

Placeholder Unit	Meaning
wd	Weekday (Sunday..Saturday)
md	Month day (1..31)
mo	Month (January..December)
y	Year
date	Date

Expressions

The language defines an expression to be either a:

• Boolean
• Number (u32)
• Placeholder unit
• Weekday (sun, mon, tue, wed, thu, fri, sat)
• Month (jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec)
• Date (YYYY-MM-DD)
• Predicate
  • Equality (e1 = e2)
  • Logical AND (e1 & e2)
  • Logical OR (e1 | e2)
  • Logical NOT (!e1)
  • Order comparison (e1 < e2, e1 <= e2, e1 > e2, e1 >= e2, can be applied to numbers and dates)
• Arithmetic
  • Addition (e1 + e2, addition between a date and a number N is the date + N days)
  • Modulo (e1 % e2)
• Functions (discussed next)

Built-in functions

Function	Parameters	Output
md	date	Month day of date
wd	date	Weekday of date
wdp	weekday, date	The date of the previous weekday
nw	date, date	The number of weeks in the span of the given dates

Preview

Settings → Appearance

Diesel offers a variety of themes (32) provided by daisyUI:

Building from source

Install the following dependencies and build the project using cargo build.

Dependencies

• Tailwind (+ typography) CSS (npm i -D tailwindcss @tailwindcss/typography)
• daisyUI (npm i -D daisyui@latest)

Dedication

In loving memory of