VictorTaelin

Implementing complex numbers and FFT with just datatypes (no floats)

In this article, I'll explain why implementing numbers with just algebraic datatypes is desirable. I'll then talk about common implementations of FFT (Fast Fourier Transform) and why they hide inherent inefficiencies. I'll then show how to implement integers and complex numbers with just algebraic datatypes, in a way that is extremely simple and elegant. I'll conclude by deriving a pure functional implementation of complex FFT with just datatypes, no floats.

quelgar

Every Argument for Static Typing Applies to Typed Errors

Think of all the arguments you've heard as to why static typing is desirable — every single one of those arguments applies equally well to using types to represent error conditions.

An odd thing I’ve observed about the Scala community is how many of its members believe that a) a language with a sophisticated static type system is very valuable; and b) that using types for error handling is basically a waste of time. If static types are useful—and if you like Scala, presumably you think they are—then using them to represent error conditions is also useful.

Here's a little secret of functional programming: errors aren't some special thing that operate under a different set of rules to everything else. Yes, there are a set of common patterns we group under the loose heading "error handling", but fundamentally we're just dealing with more values. Values that can have types associated with them. There's absolutely no reason why the benefits of static ty

snoyberg

#![feature(generic_associated_types)]
#[allow(dead_code)]

trait Functor {
    type Unwrapped;
    type Wrapped<B>: Functor;

    fn map<F, B>(self, f: F) -> Self::Wrapped<B>
    where
        F: FnMut(Self::Unwrapped) -> B;

hobwekiva

1. def hash(a: A): Int makes me sad. What about hashing to 64 bits or SL2 Fp?
2. def MapHash[A, B: Hash]: Hash[Map[A, B]] is a bit odd. Why not A: Hash?
3. reflexiveLaw + symmetryLaw + transitivityLaw is too weak for "equality". This defines a general equivalence relationship only.
4. val AnyEqual: Equal[Any] is worrisome, considering all the resolution bugs!
5. val DoubleEqual: Equal[Double] should be implemented using java.lang.Double.doubleToRawLongBits.
6. A combintation of [trait Ord[-A] extends Equal[A]](https://github.com/zio/zi

573

{ pkgs ? import <nixpkgs> {} }: {
  test = pkgs.nixosTest ./test.nix;
}

edmundsmith

Method for Emulating Higher-Kinded Types in Rust

Intro

I've been fiddling about with an idea lately, looking at how higher-kinded types can be represented in such a way that we can reason with them in Rust here and now, without having to wait a couple years for what would be a significant change to the language and compiler.

There have been multiple discussions on introducing higher-ranked polymorphism into Rust, using Haskell-style Higher-Kinded Types (HKTs) or Scala-looking Generalised Associated Types (GATs). The benefit of higher-ranked polymorphism is to allow higher-level, richer abstractions and pattern expression than just the rank-1 polymorphism we have today.

As an example, currently we can express this type:

JoeyBurzynski

58 bytes of CSS to look great nearly everywhere

When making this website, i wanted a simple, reasonable way to make it look good on most displays. Not counting any minimization techniques, the following 58 bytes worked well for me:

main {
  max-width: 38rem;
  padding: 2rem;
  margin: auto;
}

iravid

import akka.actor.ActorSystem
import akka.kafka.ConsumerMessage.CommittableMessage
import akka.kafka.scaladsl.Consumer
import akka.kafka.{ ConsumerSettings, Subscriptions }
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{ Keep, Sink => AkkaSink }
import org.apache.kafka.common.serialization.StringDeserializer
import scalaz.zio._
import scalaz.zio.stream.Sink
import scalaz.zio.interop.reactiveStreams._

jdegoes

package fpmax

import scala.util.Try
import scala.io.StdIn.readLine

object App0 {
  def main: Unit = {
    println("What is your name?")

    val name = readLine()

c0nn3r

import re
import os
import glob
import pandas as pd

import matplotlib.pyplot as plt

from collections import OrderedDict

fig_size = [12, 9]