A more powerful and stable replacement for Xcode Swift Playgrounds
<p style="text-align: center;"><blockquote class="twitter-tweet" data-dnt="true"><p lang="en" dir="ltr">How to crash #Xcode 11: New -> Playground -> UIKit -> Single View. Run.<br><br>I just remembered why I never use Xcode playgrounds.</p>— @KenHatesSoftwar <a href="https://twitter.com/KenHatesSoftwar/status/1296152018411651074">Aug. 19, 2020</a></blockquote></p>
<p style="text-align: center;"><blockquote class="twitter-tweet"><p lang="en" dir="ltr">Do Playgrounds no longer work at all in #XCode 11.0 for anyone else? They just get stuck on "Running..." & never execute any code. Even a default playground with only the default code & a "print(str)" command just hangs there doing nothing. #coding @Apple @AppleSupport #Xcode11</p>— @BioAlex <a href="https://twitter.com/bioalex/status/1177368049873301506">Sep. 27, 2019</a></blockquote></p>
<p style="text-align: center;"><blockquote class="twitter-tweet"><p lang="en" dir="ltr">Now I get why Apple requires students to submit a playground that can be experienced in at most 3 minutes to apply for a WWDC scholarship… The reviewers have to spend the remaining 57 minutes trying to get Xcode to run it successfully 🤦</p>— @BalestraPatrick <a href="https://twitter.com/BalestraPatrick/status/1109932828970700802">Mar. 24, 2019</a></blockquote></p>
<p style="text-align: center;"><blockquote class="twitter-tweet"><p lang="en" dir="ltr">Never ever praise an Xcode playground. It’s bound to crash 10 seconds later. #Swift #xcode #ios</p>— @YOADAPPS <a href="https://twitter.com/YOADAPPS/status/1075868207641231360">Dec. 20, 2018</a></blockquote></p>
Because of Xcode [Swift](https://news.ycombinator.com/item?id=24473055) Playground instability while running even the [simplest](https://twitter.com/bioalex/status/1177368049873301506) of [Swift](https://news.ycombinator.com/item?id=24593628) code, this Swift code runner was implemented with Pharo. It brings the benefits of greatly increased stability for trying short pieces of Swift code _and_ working with that output in Pharo's stable, modern, live development environment.
- - -
SwiftPlayground-Pharo
===
**Interact with Swift on Pharo.**
Run Swift with the Pharo Swift Playground, interoperate with Pharo, inspect output and Swift [ASTs](https://en.wikipedia.org/wiki/Abstract_syntax_tree).
* [Pharo 8](https://www.pharo.org/) reference platform.
* Requires:
* macOS (tested with 11.0.1) ***or*** GNU/Linux (tested with Ubuntu 14.04, 64 bit).
* Swift tools (see _Installation_ below).
## Screenshot
## TODO
- [ ] Swift Playground: `Print it`.
- [ ] Swift Playground: Syntax highlighting and code completion.
- [ ] Swift Playground: Open/save files.
- [ ] Swift response string to Pharo object deserialization.
- [ ] Move documentation to the wiki.
- [ ] Support the latest Pharo release.
- [ ] Support [Spec2](https://astares.blogspot.com/2019/08/spec2.html).
## Table of Contents
* [Installation](#installation)
* [Usage](#usage)
* [API Reference](#api-reference)
* [Swift Output and ASTs](#swift-output-and-asts)
* [Pharo Object to Swift String Serialization](#pharo-object-to-swift-string-serialization)
* [Swift Response String to Pharo Object Deserialization](#swift-response-string-to-pharo-object-deserialization)
* [Imports](#imports)
* [Asynchronous Swift Code](#asynchronous-swift-code)
* [TODO](#todo)
* [Acknowledgements](#acknowledgements)
* [Author](#author)
* [License](#license)
## Installation
1. Install and setup the Swift tools for your environment:
* **macOS:** Install the [Command Line Tools for Xcode](https://developer.apple.com/download/more/?=command%20line%20tools).
* **GNU/Linux:** [Install Swift](https://www.swift.org/getting-started/#installing-swift) from [swift.org](https://www.swift.org/).
2. In a Playground, _Do it_:
```smalltalk
Metacello new
repository: 'github://brackendev/SwiftPlayground-Pharo:v1.0.2/src';
baseline: 'SwiftPlayground';
onConflict: [ :ex | ex useIncoming ];
onUpgrade: [ :ex | ex useIncoming ];
onDowngrade: [ :ex | ex useLoaded ];
load.
```
## Usage
Swift code can be run in the Swift Playground and inline within Pharo code.
### ★ SWIFT PLAYGROUND
Write, compile, run, and inspect output of Swift code via the Swift Playground (accessible via the Tools menu).
##### Important contextual menu items:
* `Do it` – Run the selected Swift code
* `Inspect it` – Run the selected Swift code and inspect it
* `Print it` – Run the selected Swift code and print it (**TODO**)
* `Inspect AST` – Returns the Swift [AST](https://en.wikipedia.org/wiki/Abstract_syntax_tree) for the selected Swift code. For example, `print("Hello, World!")` returns:
```
(import_decl range=[Swift:1:1 - line:1:8] 'Foundation')
(top_level_code_decl range=[Swift:2:1 - line:2:22]
(brace_stmt range=[Swift:2:1 - line:2:22]
(call_expr type='<null>' arg_labels=_:
(unresolved_decl_ref_expr type='<null>' name=print function_ref=unapplied)
(paren_expr type='<null>'
(string_literal_expr type='<null>' encoding=utf8 value="Hello, World!" builtin_initializer=**NULL** initializer=**NULL**)))))
```
### ★ INLINE SWIFT
Outside of the Swift Playground, Swift code can be executed within Pharo code by using the `runSwift` string class extension. For example:
## API Reference
### SWIFT OUTPUT AND ABSTRACT SYNTAX TREES
Pharo class extensions can be used to run and view the [ASTs](https://en.wikipedia.org/wiki/Abstract_syntax_tree) of Swift code with the `runSwift` and `swiftAST` class extensions:
#### ◼︎ String class extension: `runSwift`
Returns Swift output as a string. Use the [print](https://developer.apple.com/documentation/swift/1541053-print) function within the Swift code to create output. For example:
```smalltalk
swiftString := 'The five boxing wizards jump quickly' asLowercase asSwiftString.
('let (lowercased, alphabet) = (Set(', swiftString, '), "abcdefghijklmnopqrstuvwxyz")
print("\(!alphabet.contains { !lowercased.contains($0) })")') runSwift.
```
returns `'true'`.
Tip: Simple Swift code does not need the [print](https://developer.apple.com/documentation/swift/1541053-print) function. For example:
```smalltalk
'Array("ABCDE")' runSwift.
```
returns `'["A", "B", "C", "D", "E"]'`, and:
```smalltalk
swiftArray := #(1 2 3 4 5) asSwiftArray.
(swiftArray, '.map{$0 * $0}.reduce(0, +)') runSwift.
```
returns `'55'`.
#### ◼︎ String class extension: `swiftAST`
Returns the Swift [AST](https://en.wikipedia.org/wiki/Abstract_syntax_tree) of Swift code.
### PHARO OBJECT TO SWIFT STRING SERIALIZATION
Pharo class extensions can be used as quick helpers to serialize Pharo objects to Swift code (as Pharo strings). For example, `'Hello, World!' asSwiftString` returns `'"Hello, World!"'`.
These are useful in concatenating Pharo strings of Swift code. For example, in the code below, notice the usage of `sentence` and `asSwiftString` and how they're used in the `swiftCode` string concatenation:
```smalltalk
sentence := 'The five boxing wizards jump quickly' asLowercase asSwiftString.
swiftCode := ('
// Determine a pangram
let (sentenceSet, alphabet) = (Set(', sentence, '), "abcdefghijklmnopqrstuvwxyz")
print(!alphabet.contains {
!sentenceSet.contains($0)
})
').
swiftCode runSwift.
```
returns `'true'`.
Currently, the following class extensions have been implemented. The examples are also availabe via the `SPExamples` object.
#### ◼︎ Array class extension: `asSwiftArray`
Currently only handles one depth of booleans, numbers, and strings. Example:
```smalltalk
#(1 'A' 2 true 3 false) asSwiftArray.
```
returns `'[1,"A",2,true,3,false]'`.
#### ◼︎ Boolean class extension: `asSwiftBoolean`
Example:
```smalltalk
true asSwiftBoolean.
```
returns `'true'`.
#### ◼︎ Dictionary class extension: `asSwiftDictionary`
Currently only handles one depth of booleans, numbers, and strings. Example:
```smalltalk
(Dictionary newFrom: {(1 -> 2). ('A' -> 3). (4 -> 'B'). (5 -> true).
(false -> 'C'). ('D' -> 'E')}) asSwiftDictionary.
```
returns `'[1:2,"A":3,4:"B",5:true,"D":"E",false:"C"]'`.
#### ◼︎ String class extension: `asSwiftString`
Example:
```smalltalk
'Hello, World!' asSwiftString.
```
returns `'"Hello, World!"'`.
### SWIFT RESPONSE STRING TO PHARO OBJECT DESERIALIZATION
Pharo class extensions can be used as quick helpers to deserialize Swift code (as Pharo strings) to better Pharo objects. These are useful to more easily handling Swift code ouput. For example, `'true' asPharoBoolean` returns `true`.
Currently, the following extension methods have been implemented. The examples are also availabe via the `SPExamples` object.
#### ◼︎ String class extension: `asPharoBoolean`
Example:
```smalltalk
'1 == 1' runSwift asPharoBoolean.
```
returns `true`.
### 👉🏻 EXAMPLE
An example using `asSwiftString`, `runSwift`, and `asPharoBoolean`:
```smalltalk
sentence := 'The five boxing wizards jump quickly' asLowercase asSwiftString.
swiftCode := ('
// Determine a pangram
let (sentenceSet, alphabet) = (Set(', sentence, '), "abcdefghijklmnopqrstuvwxyz")
print(!alphabet.contains {
!sentenceSet.contains($0)
})
').
swiftCode runSwift asPharoBoolean.
```
returns `true`.
## TIPS
### IMPORTS
The Apple [Foundation](https://developer.apple.com/documentation/foundation) framework is imported into Swift code automatically. To use other Apple frameworks with Swift code, use the Swift `import` directive.
### ASYNCHRONOUS SWIFT CODE
To prevent asynchronous Swift code from exiting too early, use the Swift [dispatchMain()](https://developer.apple.com/documentation/dispatch/1452860-dispatchmain) function to never return and use the Swift [exit()](https://developer.apple.com/documentation/foundation/thread/1409404-exit) function to exit where appropriate.
For example, in the Swift