hadronized

data Foo :: * -> * where -- the * -> * means that Foo expects a type to be concrete, so like Foo Int, Foo Bool, etc.
  FooInt :: Int -> Foo Int
  FooBool :: Bool -> Foo Bool
  
-- so the compiler can enforce that there is no way to build a Foo t where t is not either Int or Bool.

-- then, matching on Foo Int is exhaustive here:
matchIntOnly :: Foo Int -> Int
matchIntOnly (FooInt x) = x

hadronized

{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE Rank2Types #-}

import Data.Kind (Constraint)

-- This implementation is based on existentials; i.e. the type information is
-- lost when the type 'a' is wrapped in 'Impl c' (no 'a' anymore).
data Impl :: (* -> Constraint) -> * where

hadronized

  pub fn from_hex(hex: impl AsRef<str>) -> Option<Color> {
    let hex = hex.as_ref();
    let bytes = hex.as_bytes();
    let (mut r, mut g, mut b);

    if hex.len() == 4 && bytes[0] == b'#' {
      // triplet form (#rgb)
      let mut h = u16::from_str_radix(&hex[1..], 16).ok()?;

      b = (h & 0xf) as _;

hadronized

toBin8 :: Int8 -> Integer
toBin8 x =
      y .&. 1
    + (y `shiftR` 1 .&. 1) * 10
    + (y `shiftR` 2 .&. 1) * 100
    + (y `shiftR` 3 .&. 1) * 1000
    + (y `shiftR` 4 .&. 1) * 10000
    + (y `shiftR` 5 .&. 1) * 100000
    + (y `shiftR` 6 .&. 1) * 1000000
    + (y `shiftR` 7 .&. 1) * 10000000

hadronized

// A depends on B-0.1 and C-0.1
// B depends on C-0.1

// in C
struct Foo;
struct Bar;

// in A
fn foo(_: Foo, _: Bar);

hadronized

-- Why not this implementation?
selectM :: (Monad f) => f (Either a b) -> f (a -> b) -> f b
selectM x y = do
  e <- x
  case e of
    Left  a -> fmap ($a) y
    Right b -> b <$ y

hadronized

-- Why not this implementation?
selectM :: (Monad f) => f (Either a b) -> f (a -> b) -> f b
selectM x y = do
  e <- x
  case e of
    Left  a -> fmap ($a) y
    Right b -> fmap (const b) y

hadronized

#include <iostream>
#include <string>

struct BordelLand {
    BordelLand(bool x): tag(Graffiti::A), a(x) {}
    BordelLand(char x): tag(Graffiti::B), b(x) {}
    BordelLand(float x): tag(Graffiti::C), c(x) {}

    template <typename F> void pattern_a(F f) {
        if (tag == Graffiti::A) {

hadronized

use serde::de::{Deserialize, Deserializer, Error, Visitor};
use std::fmt;

use serde_json::de::from_str;

#[derive(Clone, Debug, Eq, PartialEq)]
enum YourFancyEnum {
  Foo,
  Bar,
  Zoo,

hadronized

Keybase proof

I hereby claim:

• I am phaazon on github.
• I am phaazon (https://keybase.io/phaazon) on keybase.
• I have a public key whose fingerprint is 3943 DF2A 2E41 24B4 5702 E6BC 4F28 29BB 996A 2EED

To claim this, I am signing this object: