https://github.com/stephencelis/formatting

Type-safe, functional string formatting in Swift.
https://github.com/stephencelis/formatting

composability formatter functional-programming string-formatter swift

Last synced: about 2 months ago
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Type-safe, functional string formatting in Swift.

• Host: GitHub
• URL: https://github.com/stephencelis/formatting
• Owner: stephencelis
• License: mit
• Created: 2016-06-26T17:41:47.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2017-02-11T22:57:00.000Z (almost 8 years ago)
• Last Synced: 2024-10-12T08:30:43.089Z (2 months ago)
• Topics: composability, formatter, functional-programming, string-formatter, swift
• Language: Swift
• Homepage:
• Size: 18.6 KB
• Stars: 248
• Watchers: 6
• Forks: 8
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# Formatting

Type-safe, functional string formatting in Swift.

Inspired by Chris Done's excellent [Haskell library](https://github.com/chrisdone/formatting).

``` swift

import Formatting

format("Hello, " % string % "!", "world")

// "Hello, world!"

```

## Introduction

Traditional string formatting methods (interpolation, `printf`, and template strings) can lead to subtle (and not so subtle) runtime bugs.

``` swift

print("Hello, \(thing)!")              // Hello, nil!

print("Hello, \(thing)!")              // Hello, Optional("world")!

```

``` objective-c

NSLog(@"Hello, %@!", thing);           // Hello, (null)!

```

**Formatting** brings compile-time checks.

``` swift

print("Hello, " % string % "!", thing) // Value of optional type String? not unwrapped

```

And composability.

``` swift

let greet =

  format("Hello, " % string % "!")

greet("world")                         // Hello, world!

```

## Composing formatters

Use `%` to build a formatter with strings and other formatters.

``` swift

format(string % " is " % int % "years old.", "Alice", 25)

// "Alice is 25 years old."

```

Use `<>` to pass the previous formatter argument to the next formatter.

``` swift

format(yyyy % "-" <> MM % "-" <> dd, Date())

// "2016-06-28"

```

Use `.%` to feed the result of one formatter into another.

``` swift

format(left(2, "0") .% hex, 10)

// "0a"

```

Call `format` without arguments to return a curried formatter function.

``` swift

let log =

  format(right(5) % " -- [" % iso8601 % "] " % string)

let infoLog = log("INFO")

let debugLog = log("DEBUG")

infoLog(Date())("Logging in...")

// "INFO  -- [2016-06-28T12:34:56Z] Logging in..."

debugLog(Date())("Logged in successfully!")

// "DEBUG -- [2016-06-28T12:34:56Z] Logged in successfully!"

```

## License

Formatting is available under the MIT license. See [the LICENSE

file](./LICENSE.txt) for more information.