(sixteenth RacketCon) is almost here!
We have an amazing program and a rockstar keynote speaker.
See the program con.racket-lang.org and get your ticket at www.eventbrite.com/e/racketcon-...
Only nine days to go, I can already taste the excitement.
con.racket-lang.org
(sixteenth RacketCon)
![Comic. [Back of car with bumper sticker reading “I forth [red heart emoji]”]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cz73r7iyiqn26upot4jtjdhk/bafkreie63wpgnvtc2bwmewc5o7vjndx7okspndmqn73ifodbzfzvs5nnyi)
![```python
// efficient functional data structures
class Tree(val, children :: List.of(Tree)):
method flatten(): // O(N log N) for N `val`s
for fold(lst = [val]) (child in children):
// because append with `++` is O(log N)
lst ++ child.flatten()
Tree(1, [Tree(2, [Tree(4, [])]),
Tree(3, [Tree(5, [])])])
.flatten() // ⇒ [1, 2, 4, 3, 5]
```
(the 'python’ syntax highlighting in most markdown-like environments is sufficient for Rhombus)
Rhombus Programming Language
https://rhombus-lang.org
#rhombus](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreictnwp7loxsw2uccthkufypczo2yrkafdkbe3qvvo3ltzkavjfbpq)
![```
// pattern matching in all binding positions
class Posn(x, y)
fun flip_all([Posn(x, y), ...]):
[Posn(y, x), ...]
flip_all([Posn(1, 2), Posn(3, 4)])
// ⇒ [Posn(2, 1), Posn(4, 3)]
flip_all([Posn(5, 6)])
// ⇒ [Posn(6, 5)]
```
https://rhombus-lang.org](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreif5sne7ldzu4tykhhspfy3wtsq33quaoxfibbc4r2jh6lgbdhkpli)
![Code sample from https://rhombus-lang.org
```rhombus
// ellipses to create and use repetitions
fun all_same([str0, str, ...]):
all(str0 == str, ...)
all_same(["hello", "hello", "hello"])
// ⇒ #true
all_same(["hello", "goodbye", "hello"])
// ⇒ #false
```](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreiazg6yfkwfp4cjihu2xdkz5qzhx4vnzx4ydgbn6k3x5hzrrwwk74m)
![// `for` as a general-purpose iteration and
// comprehension form
fun i_repeat(str :: String, n :: Nat) :: List:
for List (i in 0..n):
i+1 +& ". " +& str
i_repeat("hello", 3)
// ⇒ ["1. hello", "2. hello", "3. hello"]
https://rhombus-lang.org](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreiha5ammrikcikbq6rwfzpu2imdyrnxoqh2r7fnprqzkjedbjxd4ua)
![// `:` for nesting, `|` for alternatives,
// `::` for type-like checked annotations
fun repeat(str :: String, n :: Nat) :: List:
if n == 0
| []
| [str] ++ repeat(str, n-1)
repeat("hello", 3)
// ⇒ ["hello", "hello", "hello"]
repeat(3, "hello")
// ⇒ error: 3 is not a String
https://rhombus-lang.org](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreiakvxttta5vwxrzxswpwvh2marozr74uopagsyblyicej7ewmv43a)
![// pattern matching on objects, lists, and maps
class Rect(left, top, right, bottom)
fun rect_like_to_rect(v):
match v
| Rect(_, _, _, _): v
| {"LT": [l, t], "RB": [r, b]}: Rect(l, t, r, b)
| {"TL": [t, l], "BR": [b, r]}: Rect(l, t, r, b)
rect_like_to_rect({"LT": [0, 2], "RB": [10, 5]})
// ⇒ Rect(0, 2, 10, 5)
rect_like_to_rect({"TL": [0, 2], "BR": [10, 5]})
// ⇒ Rect(2, 0, 5, 10)](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:55jpbxvlzoxmt4karrkj6mre/bafkreigkn4zyt5ajjhx3gwflbq32zlb3cm7vbwqaesrlxxeulhuaifml64)
