deech

;; -*- mode: dotspacemacs -*-
;; This file is loaded y Spacemacs at startup.
;; It must be stored in your home directory.

(defun dotspacemacs/layers ()
  "Configuration Layers declaration."
  (setq-default
   ;; List of additional paths where to look for configuration layers.
   ;; Paths must have a trailing slash (ie. `~/.mycontribs/')
   dotspacemacs-configuration-layer-path '()

deech

(datatype whisky
    if (element? X [bourbon scotch])
    ________________________________
    X : whisky;)

(datatype beer
    if (element? X [lager stout])
    ______________________________
    X : beer;)

deech

Most remember Pieter Hintjens for his messaging protocols. I don't know anything about that, 
but I credit him with rekindling my love of programming in general, Lisp and functional programming 
in one fell swoop about 17 years ago.

He did this by writing 'Libero', a mid-90's C program that took an ASCII diagram of a state machine 
and produced code that ran that machine in a remarkable number of languages including 'sh', 'python',
'C' and many more. Some of them are listed on the original page (https://imatix-legacy.github.io/libero/).
I discovered in the early 00's and it fascinated me because was a unique combination of code generation
and what is now called purely functional programming. 

deech

monadic = do
  x <- [0,1]
  y <- [0,2]
  return (x + y)
applicative = (+) <$> [0,1] <*> [0,2]
comprehension = [(x + y) | x <- [0,1], y <- [0,2] ]
main = do
  print monadic
  print applicative
  print comprehension

deech

(define string-concat
{ (list string) --> string }
  [] -> ""
  [S] -> S
  [S | Ss] -> (@s S " " (string-concat Ss)))

(datatype verified-types-for-lists

  _______________________________________
  (empty? Xs) : verified >> Xs : (list A);

deech

(defun nset-element-at (path ast new-element)
  (if (= 0 (length path))
      (setf ast new-element)
    (let ((place-fn)
          (path (reverse path)))
      (progn
        (dotimes (current-index (length path) nil)
          (setq place-fn
                (if (= current-index 0)
                    (list 'nth (nth current-index path) 'ast)

deech

{-
This code shows how to check if a type-level list contains a given type.
It first shows the approach required for older versions of GHC (< 7.6.x)
and then a version using closed type families supported in GHC 7.8.1 and greater.
-}

{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}

deech

import Control.Monad
import Text.Parsec

testString = unlines [
                      "foo {",
                      "  contents of foo",
                      "  a stray }",
                      "}",
                      "bar {",
                      "}"

deech

{-# LANGUAGE GADTs, UndecidableInstances, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, FlexibleContexts, ScopedTypeVariables, OverlappingInstances, EmptyDataDecls #-}

data A a
data B a
data C a
data D a
data E a
data F a

type AToF =

deech

;; Neat way of getting all Emacs functionality in Evil's insert mode

(defun with-evil-mode (mode key-behavior-pairs)
  (mapcar #'(lambda (pair)
              (define-key
                mode
                (car pair)
                (cdr pair)))
          key-behavior-pairs))