codesections

Persistent Data Structures for Raku

Synopsis

Immutable, persistent data structures give a program certain superpowers that it's very hard to have in any other way: they allow the program to "time travel" (view previous application state); they allow let the program share data across threads or asynchronously save it to disk without needing locks; they enable a much more purely functional style of programming – which results in code that many software developers find much easier to reason about. Because of these benefits, many languages with strong support for functional programming (Clojure, Elm, Haskell, etc) offer

codesections

my $result = do try {
  # some code that may throw X::This
  …
  # some code that may throw X::NotSpecified (default)
  …
  # some code that may throw X::Something
  …
  # some code that may throw X::This or X::That
  …

codesections

sub postfix:<‽>($a) { $ = $a};
class A { method n { Nil };
          method fine { self }
          method non-nil { 42}
        };
say A.new.fine‽
         .non-nil;

say A.new.n‽
         .non-nil;

codesections

in←↑⊃⎕nget '10.input' 1 ⋄ p←'#'=in

can_see←{⍺≡⍵:0
          0=+/¯1↓{p[⍵[0];⍵[1]]}¨⍺ els_btwn ⍵ }

els_btwn←{ ⍺≡⍵:⍬
           n←⍺+(⍺ slope_btwn ⍵)
           (⊂n),(n ∇ ⍵) }     

slope_btwn←{{⍵÷(∨/⍵)}-⍺-⍵}                                                         

codesections

intcode←{        
  ⍺←0 0 ⋄ (i rb)←⍺ ⋄ val←⊃⍵[0] ⋄ addr←⊃⍵[1]
  get←{ ⍵<0: ⎕←'ERR: invalid negative index'
        (addr⍳⍵)<(≢addr):(addr⍳⍵)⌷val
        addr,←⍵ ⋄ val,←0 ⋄ ∇ ⍵ }
  set←{ (addr⍳⍺)<(≢addr):((addr⍳⍺)⌷val)←⍵ 
        addr,←⍺ ⋄ val,←⍵ }      
  instr←(10 10 10 10 10)⊤(get i) ⋄ opcode←(10 10)⊥¯2↑instr ⋄ p_modes←⌽3↑instr

  p←{mode←p_modes[⍵-1]  

codesections

⎕IO←0
intcode←{
  ⍺←0 ⋄ i←⍺ ⋄ s←⍵ ⋄ instr←'0'(,⍣{4<≢⍺})⍕⍺⌷⍵ ⋄ opcode←⍎¯2↑instr ⋄ p_modes←⍎¨⌽3⍴instr
 
  p←{mode←p_modes[⍵-1]
     mode=0:s[i+⍵]
     mode=1:i+⍵
     'ERR: Unknown parameter mode',mode}

  i≥≢s:'ERR: no HALT opcode'

codesections

⎕IO←0    
find←{
  ⍺←0
  in←(⊃⍺⌷,(⍳100)∘.,⍳100) set ⊃0⌷⍵
  (⊃1⌷⍵)=0⌷intcode in:in[1 2]
  (⍺+1)∇in (⊃1⌷⍵)
}                    
set←{s←⍵ ⋄ s[1 2]←⍺[0 1] ⋄ s}
intcode←{
  ⍺←0 ⋄ s←state←⍵

codesections

keycode   8 =
keycode   9 = Escape NoSymbol Escape
keycode  10 = 1 exclam 1 exclam
keycode  11 = 2 at 2 at
keycode  12 = 3 numbersign 3 numbersign
keycode  13 = 4 dollar 4 dollar
keycode  14 = 5 percent 5 percent
keycode  15 = 6 asciicircum 6 asciicircum
keycode  16 = 7 ampersand 7 ampersand
keycode  17 = 8 asterisk 8 asterisk

codesections

#[derive(Debug)]
pub struct LinkedList {
    head: Option<Box<Node>>,
    tail: Option<*mut Node>,
}
#[derive(Debug)]
struct Node {
    value: i32,
    next: Option<Box<Node>>,
}

codesections

(defun factorial (n)
  (if (zerop n) 1 (* n (factorial (1- n)))))