Programming language cheatsheet

I work with many programming languages, it is sometimes hard to remember the names basic stuff as they differ just a little bit across languages.

1. Cheatsheet: Array

What	JavaScript
Documentation	Array (MDN)
Creating a new array from two arrays	`const newArray = array1.concat(array2);`
Append an array to an existing one (destructively)	`array1.push(...array2);`
Add an element to the end of an array (destructively)	`.push()`
Remove the last element of an array (destructively)	`.pop()`
Add an element to the beginning of an array (destructively)	`.unshift()`
Remove the first element of an array (destructively)	`.shift()`
Remove an item at index (destructively)	`.splice(i, 1)`

This one is annoying because each language have different names for the abstract data type and then have even more names for a bunch of variants.

What	JavaScript	Python	Lisp	Ruby
Creating an empty set	`new Set()`	`Set()`	`'()` or `(make-hash-table)`

In javascript, the for ... of syntax does not work for object, as they are not iterable.

To get something you can iterate on, you can use one of these static methods:

Example:

const obj = { a: 1, b: 2, c: 3 };
for(let [key, value] of Object.entries(obj)) ...

const isString = x => typeof x === 'string' || x instanceof String;

isinstance(x, str)

(stringp x)

x.constructor.name

x.__class__
x.__class__.__name__

(class-of x)
(class-name (class-of x))

const isElement = x => x.tagName || x.nodeName;

const delay = ms => new Promise(resolve => setTimeout(resolve, ms));

(defun delay (seconds function)
  (bt:make-thread
   (lambda ()
     (sleep seconds)
     (funcall function))))

N.B. Those terms are not always a perfect match.

Javascript	Python	Lisp	Ruby
default function parameters	default argument values	optional parameters	`arguments with default expression are optional`
throw	raise	signal or error	raise
destructuring assignment		destructuring-bind	pattern matching + pin operator
spread syntax	unpacking	apply	splat operator
rest paramteters	packing	rest parameters
		call-next-method	argument forwarding
	structural matching		pattern matching
			rightward assignment
			destructuring method
		∄	pin operator

cat <<EOF
  as is
EOF

cat <<-EOF
                <<- removes leading tabs
        but not
    spaces
EOF

slugify () {
    echo "$1" | iconv -t ascii//TRANSLIT | sed -r 's/[~\^]+//g; s/[^a-zA-Z0-9]+/-/g; s/^-+\|-+$//g' | tr A-Z a-z
}