fi - Functional conditionals

With fi you can ignore the language constructs and write all your conditional logic in a functional way.

usage with Typescript

``typescript
import { fi } from 'fi'

const myVar: string = fi(false, 'The dragon')
.elseif(
() => 1 == 2,
() => 'Vampire',
)
.else('Wargulf')
.ret()
`

usage with javascript / CommonJS

`javascript
const { fi } = require('fi')

const myVar = fi(false, 'The dragon')
.elseif(
() => 1 == 2,
() => 'Vampire',
)
.else('Wargulf')
.ret()
`

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The library is distributed as an npm module:

`sh
npm install fi
`

or

`sh
yarn add fi
`

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Basic if statement

`typescript
const getIfTrue = fi(true, 'flower puppy')

// getIfTrue() returns "flower puppy"
`

We can make it more interesting and add an elseif & else statements:

`typescript
const getIfTrue = fi(false, 'flower puppy')
.elseif(() => false, 'something else')
.else('space pedals')

// getIfTrue() returns 'space pedals'
`

Even more interesting using an if-else statement as well:

With a half completed if statment, we can also start chaining more stuff to it later

`typescript
const myif = fi(false, 'flower puppy').elseif(false, 'human skin')

// do some other stuff, and add to the chain:
const myVar = myif.else('crapware')

// myVar is "crapware"
`

Any value passed into any fi conditional or return value can be a function

Functions that don't meet a conditional are never executed, and conditionals that dont' meet a
condition (like an else if conditional in an if statement evaluated as true) will also never
get executed.

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The ternary variant is not chainable and does not return a function

`typescript
import { ternary } from 'fi

const myVar = ternary(() => 1 > 4), () => 15, () => 42)

// myVar is 42
`

Switch statement using an object:

`javascript
var sw = require('fi').sw

var myVar = sw('Rainbow', {
red: 'Redish',
green: 'Greenish',
blue: 'Blueish',
default: 'Some color',
})

// myVar is "Some color"
`

Switch statement using an array (so you can use functions as your keys):

`javascript
var myVar = sw("Rainbow",
() => "red", "Redish",
() => "green", () => "Random green",
() => "blue", "Blueish",
() => "Some color" // our default
})

// myVar is "Some color"
``

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1. I don't know
2. It could potentially lead to some interesting use cases

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Arnor Heidar Sigurdsson
[@arnorhs on Twitter

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MIT