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try! Swift Tokyo 2024 After Talk
Presented by: Kenta Enomoto, STORES, Inc.
Date: March 27, 2024
Introducing Pkl
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About Me
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Kenta Enomoto
STORES, Inc.
Branded App Team iOS Engineer
twitter.com/enomotok_
github.com/enomoto
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About Pkl
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● An open-source language developed by Apple
● Configuration that is programmable,
scalable, and safe
● Generates output for JSON, YAML, Property
Lists, XML, and more
● /ˈpɪk.əl/
https://pixabay.com/photos/pickles-blanks-cucumbers-1799731/
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Basic Syntax
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name = "Swallow"
job {
title = "Sr. Nest Maker"
company = "Nests R Us"
yearsOfExperience = 2
}
sample.pkl
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Basic Syntax (with Class)
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amends "../Environment.pkl"
appmakerClientId = "a1b2c3d4e5g6h7i8j9k0A1"
appmakerTemplateId = "4649"
isDarkContentBarStyle = true
itemsPerPage = 20
appearance {
colorAccent = "#333333FF"
colorAccentLight = "#D3D3D3FF"
colorPrimary = "#FFFFFFFF"
}
myEnvironment.pkl
import "Appearance.pkl"
appmakerClientId: String
appmakerTemplateId: String
isDarkContentBarStyle: Boolean
itemsPerPage: Int
appearance: Appearance
Environment.pkl
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Validation
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import "Appearance.pkl"
appmakerClientId: String
appmakerTemplateId: String(this.length == 4)
itemsPerPage: Int(this > 0 && this < 50)
isDarkContentBarStyle: Boolean
appearance: Appearance
Environment.pkl
colorAccent: String(this.startsWith("#") && (this.length == 7 || this.length == 9))
colorAccentLight: String(this.matches(Regex("^#([0-9A-Fa-f]{6}|[0-9A-Fa-f]{8})$"))) // You can
even use regex
colorPrimary: String
Appearance.pkl
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Code Generation with Pkl
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amends "../Environment.pkl"
appmakerClientId =
"a1b2c3d4e5g6h7i8j9k0A1"
appmakerTemplateId = "4649"
isDarkContentBarStyle = true
itemsPerPage = 20
appearance {
colorAccent = "#333333FF"
colorAccentLight = "#D3D3D3FF"
colorPrimary = "#FFFFFFFF"
}
myEnvironment.pkl
{
"appmakerClientId":
"a1b2c3d4e5g6h7i8j9k0A1",
"appmakerTemplateId": "4649",
"isDarkContentBarStyle": true,
"itemsPerPage": 20,
"appearance": {
"colorAccent": "#333333FF",
"colorAccentLight": "#D3D3D3FF",
"colorPrimary": "#FFFFFFFF"
}
}
my_environment.json
$ pkl eval -f json myEnvironment.pkl -o my_environment.json
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Use Cases
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● Originally developed as a server technology
● Generate Kubernetes manifest files
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Use Cases for iOS Apps
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● Automatically generate multiple apps from the same codebase by
injecting configuration items.
● For managing the configuration of large applications with YAML or
JSON, you can generate configuration files with type safety (Hello
XcodeGen.)
● Let me know your ideas.
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Integration with iOS Apps
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● PklSwift
○ Swift Code generation from Pkl
○ fully type-safe
○ Interface with Swift Concurrency
○ https://github.com/apple/pkl-swift
● PklSwift does not work for iOS (yet.)
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Integration with iOS Apps
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Generate property lists and JSON files using the pkl eval command.
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References
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https://pkl-lang.org/
https://github.com/apple/pkl
https://github.com/apple/pkl-swift
https://news.ycombinator.com/item?id=39232976
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Thank you
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Enjoy your daily configuration :D