witt3rd

data Foo a = Bar a
           | Baz (Foo a) (Foo a)

fooEq : DecEq a => a -> a -> Foo a -> Foo a -> Maybe (Foo a)
fooEq x y f g = case decEq x y of
  Yes _ => Just (Baz f g)
  No  _ => Nothing

comb : DecEq a => Foo a -> Foo a -> Maybe (Foo a)
comb f@(Bar x  ) g@(Bar y  ) = fooEq x y f g -- < ok

witt3rd

Z Notation (zed)

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{zed-csp}
\usepackage{amsthm}

\theoremstyle{definition}

witt3rd

Idris Cookbook

From Haskell

newtype

newtype WorldM a = WorldM { asT :: WorldT a }

witt3rd

data Foo : (x : List a) -> (y : List b) -> Type where
  MkFoo : (bar: a -> b) -> Foo x y

bar : Foo {a} {b} x y -> a -> b
bar (MkFoo _) x' = ?rhs

{-
  b : Type
  a : Type
  y : List b

witt3rd

record Foo where
  constructor MkFoo
  from : Type
  to : Type

bar : (a : Foo) -> (x : from a) -> (to a)
-- impl not important

baz : (a : Foo) -> (b : Foo) -> ((to b) = (from a)) => (x: from b) -> (to a)

witt3rd

module RandomDouble

import Data.Bits
import Data.Vect
import Effects
import Effect.StdIO
import Effect.Random

-- 2^53 as an Integer
twoTo53 : Integer

witt3rd

Git and Github

Git

Listing the files in a commit

git diff-tree --no-commit-id --name-only -r 289b092d

Clearing Git History

witt3rd

nix

Install

macOS

Follow the recommended approach to prepare for the standard Linux install (below).

Linux / WSL

witt3rd

Haskell

Setup

• Get Haskell Stack
• And [Haskell VS Code Extension)(https://marketplace.visualstudio.com/items?itemName=haskell.haskell)

curl -sSL https://get.haskellstack.org/ | sh

witt3rd

GraphQL requests to CKG services

// wrap in async function
return (async () => {
  // request graphql
  const data = await input.__requestCkg({
    svcRef: "/service/donald-hello-world",
    query: "query { allFoos { id } }"
  })