jproyo

Rust in a Nutshell

Table of Contents

• Rust: The Language
  • Borrow Checker
  • Macros
  • Parallelism & Concurrency
  • Example
• Dependency injection

jproyo

module Format.Stdout where

import           Control.Program
import qualified Data.Map.Strict               as M
import           Relude

output :: Histogram -> IO ()
output =
  mapM_ (\(k, v) -> putStrLn $ show k ++ " " ++ replicate (fromIntegral v) '#') . M.assocs

jproyo

\documentclass{article}
\usepackage{amsmath}

\begin{document}

Five ways to prove $P \implies Q$

\begin{itemize}
\item \textbf{Direct Proof}: $P \implies Q$ 
\item \textbf{Proof by Contrapositive}: $\neg Q \implies \neg P$ 

jproyo

{-# LANGUAGE TypeOperators #-}
module HsOpTy where

import GHC.TypeLits

-- brittany-disable-next-binding
type Foo = 
  Int :
  '[]

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{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE OverloadedStrings #-}

module Test where

import           Data.Aeson
import           Data.ByteString.Lazy as BL
import           Data.Text as T

data User = User { name    :: Text

jproyo

You'll generally want to look at:

• heap
• stack
• gc profiles

Do not get bogged down in microoptimizations before you've assessed any macro optimizations that are available. IO and the choice of algorithm dominate any low level changes you may make. In the end you have to think hard about your code!

Topos> For example, if i see that a particular pure function is taking a  long time relative to the rest of the code, and that it's Text, and I'm seeing ARR_WORDS rise linearly in the heap, I probably have a thunk-based memory leak. This is knowledge you build up over time.

jproyo

Tips for Spacemacs with Haskell

• C-c C-l => Load ghci in place with the current buffer
• <SPC> C-r => Reformat region hindent
• , F => Format imports
• , f => hindent
• , r b => hlint refactor buffer
• , r s => suggestions
• , r r => refactor at point
• , h i => info at point

jproyo

# stylish-haskell configuration file
# ==================================

# The stylish-haskell tool is mainly configured by specifying steps. These steps
# are a list, so they have an order, and one specific step may appear more than
# once (if needed). Each file is processed by these steps in the given order.
steps:
  # Convert some ASCII sequences to their Unicode equivalents. This is disabled
  # by default.
  # - unicode_syntax:

jproyo

#!/bin/bash

stack install apply-refact hlint stylish-haskell hasktags hoogle intero hindent ispell
brew install ispell

jproyo

{-# LANGUAGE GeneralisedNewtypeDeriving #-}

module Data where

type UserName = String

data DataResult = DataResult String
  deriving (Eq, Show)

class Monad m => Cache m where