jrsinclair

// @flow strict-local

// Lenses
// ------------------------------------------------------------------------------------------------

export type LensInternal<S, T, A, B> = {
    getVal: (S) => A,
    setVal: (B, S) => T,
};

ChrisPenner

const all = (...preds) => (obj) => preds.map(f => f(obj)).reduce((a, b) => a && b, true)
const any = (...preds) => (obj) => preds.map(f => f(obj)).reduce((a, b) => a || b, false)
const oneOf = (...preds) => (obj) => preds.map(f => f(obj)).reduce((a, b) => a ? !b : b, false)
const has = (prop) => (obj) => obj[prop] !== undefined
const not = (pred) => (obj) => !pred(obj)
const equals = (prop, val) => (obj) => obj[prop] === val
const implies = (f, g) => (obj) => !f(obj) || g(obj);

const validate = all(implies(has('selectedIndex'), equals('isOpen', true)))

ChrisPenner

After listening to the latest Magic Read-along episode "You should watch this" (which you should go listen to now) I got caught up thinking about Brian's idea of an Endomorphism version of Kleisli composition for use with Redux, it's actually a very similar model to what I'm using in my event framework for event listeners so I figured I'd try to formalize the pattern and recognize some of the concepts involved. IIRC Brian described the idea of a Redux-reducer, which is usually of type s -> Action -> s, it takes a state and an action and returns a new state. He then re-arranged the arguments to Action -> s -> s. He then recognized this as Action -> Endo s (an Endo-morphism is just any function from one type to itself: a -> a). He would take his list of reducers and partially apply them with the Action, yielding a list of type Endo s where s

dhunmoon

function exportToCsv(filename, rows) {
        var processRow = function (row) {
            var finalVal = '';
            for (var j = 0; j < row.length; j++) {
                var innerValue = row[j] === null ? '' : row[j].toString();
                if (row[j] instanceof Date) {
                    innerValue = row[j].toLocaleString();
                };
                var result = innerValue.replace(/"/g, '""');
                if (result.search(/("|,|\n)/g) >= 0)

luceos

#!/usr/bin/env bash
# MIT © Sindre Sorhus - sindresorhus.com

# git hook to run a command after `git pull` or `git checkout` if a specified file was changed
# Run `chmod +x post-checkout` to make it executable then put it into `.git/hooks/`.

changed_files="$(git diff-tree -r --name-only --no-commit-id HEAD@{1} HEAD)"

check_run() {
	echo "$changed_files" | grep --quiet "$1" && echo " * changes detected in $1" && echo " * running $2" && eval "$2"

amboutwe

<?php
/********* DO NOT COPY THE PARTS ABOVE THIS LINE *********/

/*
 * Replace Disallow with Allow Generated Robots.txt
 * Credit: Unknown
 * Last Tested: June 09 2020 using WordPress 5.4.1
 */

add_filter('robots_txt','custom_robots');

evilsoft

const { Pred, mconcat, isArray, not, isEmpty,  safe } = require('crocks')

const pred =
  mconcat(Pred, [ not(isEmpty), isArray ])

// maybeArray : a -> Maybe []
const maybeArray =
  safe(pred)

console.log(maybeArray([ 1, 2 ])) // Just [ 1, 2 ]

jdegoes

-- A sequential series of parallel program fragments in `f`:
type SeqPar f a = Free (FreeAp f) a

liftFA :: forall f a. f a -> SeqPar f a
liftFA = pure >>> pure

liftSeq :: forall f a. Free f a -> SeqPar f a
liftSeq fa = foldFree fa liftFA

liftPar :: forall f a. FreeAp f a -> SeqPar f a

getify

Parens And Performance

Years ago, some smart folks that worked on JS engines realized that not all JS that's loaded into a page/app initially is needed right away. They implemented JIT to optimize this situation.

JIT means Just-In-Time, which means essentially that the engine can defer processing (parsing, compiling) certain parts of a JS program until a later time, for example when the function in question is actually needed. This deferral means the engine is freer to spend the important cycles right now on the code that's going to run right now. This is a really good thing for JS performance.

Some time later, some JS engine devs realized that they needed to get some hints from the code as to which functions would run right away, and which ones wouldn't. In technical speak, these hints are called heuristics.

So they realized that one very common pattern for knowing that a function was going to run right away is if the first character before the function keyword was a (, because that usually m

dtipson

/*
  Native Arrays are not great structures for cellular automata.
  Non-empty, circular, doubly-linked lists would be ideal...
  but all we really need to do is write a comonadic-like interface 
  such that it _pretends_ that the array is circular, and can thus
  pass the exfn below a sort of "local" slice of an Array as if it were circular. 
  So you can mostly ignore the implementation mess below
*/
Array.prototype.extendNear = function(exfn){
  const len = this.length;