Concatenative Programming

Alright, show me I'm not the only one in this community, and show off some solutions!

Here's my Day 1 solution in Factor (minus imports):

: get-input ( -- left-list right-list )
  "aoc-2024.01" "input.txt" vocab-file-lines
  [ split-words harvest ] map unzip
  [ [ string>number ] map ] bi@ ;

: part1 ( -- n )
  get-input
  [ sort ] bi@
  [ - abs ] 2map-sum ;

: part2 ( -- n )
  get-input
  histogram
  '[ dup _ at 0 or * ] map-sum ;

Sadly, Factor doesn't get highlighted properly here, so here it is again as an image:

I probably won't last the week, but what solutions I do have will be up on GitHub.

This example is my justification for posting it here:

"NeoHaskell is cool"
  |> Text.toWordList
  |> List.map Text.length
  |> List.map (\x -> x * x)
  |> List.takeIf Int.isEven

I posted this project here before, but it's now reached 1.0.0.

Hey, it includes Factor!

• Discussion on reddit
• Manual

This is not my own project!

Discussion on HackerNews

Slint is a GUI toolkit, and is largely not relevant to concatenative programming. But the latest release adds a touch of postfix to the mix, which is nice to see.

From the blog post:

Math Gains Postfix Support

A subtle but profound change to the language. Traditional syntax:

Math.max(20, Math.abs(value.x))

New postfix syntax:

value.x.abs().max(20)

The new syntax improves readability by making the transformation steps more explicit. It works well for many operations but has limitations:

Effective for simple transformations (e.g., abs, max) Less intuitive for operations like clamp or atan2.

pos.y.atan2(pos.x) // Less clear than atan2(pos.y, pos.x)

So for now you cannot use postfix for all functions in the Math namespace. We may revisit these cases later, so give them a try and let us know your thoughts.

Discussion on lobsters

Explanation: https://gist.github.com/Dobiasd/bb9d38a027cf3164e66996dd9e955481

I am not the author.