List of Truthies and Falseys

truthy-and-falsey.md

Truthies and falseys are defined here as things which can be placed at the condition part of if statement.

C#

https://msdn.microsoft.com/library/system.boolean.aspx

// `bool` keyword is an alias of `System.Boolean`.
bool truthy = true;
Boolean truthy2 = true;

bool falsy = false;
Boolean falsy2 = false;

CoffeeScript

http://coffeescript.org/#conditionals

# same as JavaScript
truthies = [true, 1, 'string', new Object()]

falseys = [false, null, undefined, +0, -0, NaN, '']

Groovy

http://groovy.codehaus.org/Groovy+Truth

truthies = [true, 1, [false], "false"]

falseys = [false, 0, [], "", null]

Haskell

https://www.haskell.org/onlinereport/haskell2010/haskellch3.html#x8-320003.6

truthy :: Bool
truthy = True

falsey :: Bool
falsey = False

Java

boolean truthy = true;
Boolean truthy2 = true;

boolean falsy = false;
Boolean falsy2 = false;

JavaScript

http://www.ecma-international.org/ecma-262/5.1/#sec-9.2

var truthies = [true, 1, 'string', new Object(), new String('')];

var falseys = [false, null, undefined, +0, -0, NaN, ''];

OCaml

let truthy : bool = true ;;

let falsey : bool = false ;;

PureScript

truthy = true :: Boolean

falsey = false :: Boolean

Ruby

http://docs.ruby-lang.org/en/2.1.0/syntax/literals_rdoc.html#label-Booleans+and+nil

truthies = [true, 0, "", [], Object.new] # and any other objects except for nil, false

falseys = [false, nil]

Scala

val truthy: Boolean = true

val falsey: Boolean = false

Scheme

(define truthies '(#t 1 (1 2) ())) ; and anything except #f

(define falsy #f)