SoulverCore

SoulverCore is a framework that lets you evaluate day-to-day mathematical expressions. It powers the popular notepad-calculator app Soulver. It has a very simple API with sensible defaults. It is also quite customizable. You can also access SoulverCore via a web-based API.

Requirements

Xcode 11+
Swift 5+

Supported Platforms

SoulverCore is distributed as a binary framework (.xcframework) and supports macOS, iOS, & iPadOS.

macOS 10.14.4+
iOS/iPadOS 12.2+

Installation

Drag SoulverCore.xcframework into the Frameworks, Libraries, and Embedded Content section of the General settings for your Mac or iOS target.

Getting Started

To calculate the result of a single expression, use a Calculator object:

import SoulverCore

let calculator = Calculator(customization: .standard)
let result = calculator.evaluate("123 + 456")
print("The answer is \(result.stringValue)") // prints 579

SoulverCore has a lot of features apart from basic arithmetic. These include unit conversions, date & calendar calculations, rate calculations, percentage phrase functions, and time zone conversions. It also cleverly ignores "meaningless" words:

calculator.evaluate("$10 for lunch + 15% tip") // $11.50
calculator.evaluate("65 kg in pounds") // 154.32 lb
calculator.evaluate("40 as % of 90") // 25%
calculator.evaluate("$150 is 25% on what") // $120
calculator.evaluate("$25/hour * 14 hours of work") // $350.00
calculator.evaluate("January 30 2020 + 3 months 2 weeks 5 days") // 19 May
calculator.evaluate("9:35am in New York to Japan") // 10:35 pm
calculator.evaluate("$25k over 10 years at 7.5%") // $51,525.79 (compound interest)

Variables

Use a VariableList to customize variables in your expression:

let variableList = VariableList(variables:
    [
        Variable(name: "a", value: "123"),
        Variable(name: "b", value: "456"),
    ]
)
calculator.evaluate("a + b", with: variableList) // 579

Output Formatting

Use a FormattingPreferences to customize the formatting of your result.

var formattingPreferences = FormattingPreferences()
formattingPreferences.dp = 2 // decimal places
calculator.formattingPreferences = formattingPreferences

calculator.calculate("π") // 3.14

Custom Units

You can add custom units to an EngineCustomization object.

var customization: EngineCustomization = .standard

customization.customUnits = [
    CustomUnit(name: "parrots", definition: 15, equivalentUnit: .centimeters),
    CustomUnit(name: "python", definition: 570, equivalentUnit: .centimeters)
]

let calculator = Calculator(customization: customization)
calculator.calculate("1 python in parrots") // 38 parrots

Locale settings

SoulverCore respects the decimal separator and thousands separator of the current locale. Alternatively, convert the standard EngineCustomization to another locale:

let europeanLocale = Locale(identifier: "en_DE") // In Germany a comma is used as the decimal separator
let localizedCustomization = EngineCustomization.standard.convertTo(locale: europeanLocale)

let calculator = Calculator(customization: localizedCustomization)
calculator.calculate("1,2 + 3,4") // 4,6

Multi-line calculations

Use a LineCollection to represent a list of lines to be evaluated. The LineCollection creates its own calculator, though you can still pass in your own customization.

let multiLineText =
"""
a = 10
b = 20
c = a + b
"""
        
let lineCollection = LineCollection(multiLineText:
    multiLineText, customization: .standard)

// Calculate the result of each line (synchronously)
lineCollection.evaluateAll()

// Use subscripts to get access to particular lines' results
let result = lineCollection[2].result // 30

Line References

A line collection manages dependencies between lines. You can also get a "reference" to a line. A reference is a single unicode character, which is a placeholder for the line's answer (which will be substituted in during evaluation).

let multiLineText =
"""
10
20
"""

let lineCollection = LineCollection(multiLineText:
    multiLineText, customization: .standard)

let referenceToFirstLine = lineCollection.makeReferenceForLineAt(lineIndex: 0)
let referenceToSecondLine = lineCollection.makeReferenceForLineAt(lineIndex: 1)

lineCollection.addLine("\(referenceToFirstLine) + \(referenceToSecondLine)")

// Calculate the result of each line
lineCollection.evaluateAll()

print(lineCollection[2].result!.stringValue) // 30

Currency Rates

The standard customization comes with rates for 170 real-world currencies, that were accurate at the time the framework was last compiled. You can update these currencies to the latest rates by setting valid API key credentials for CurrencyLayer and Nomics on the shared CurrencyList. Alternatively use the .popular default currency set to pull 33 currency rates from the European Central Bank, no API key required.

To fetch the latest rates, use SoulverCore's shared CurrencyList:

CurrencyList.shared.defaultCurrencySet = .popular // 33 popular currencies from the ECB, updated every weekday.

CurrencyList.shared.refreshRates { (success) in
	
	if success {  
		// The standard customization will now have the latest currency rates applied		
		let calculator = Calculator(customization: .standard)
		let result = calculator.calculate("10 USD in EUR")  		
	}
	
}

Additional languages

SoulverCore is localized into German, Russian, and simplified Chinese.

Carthage Support

SoulverCore supports Carthage. Add the following binary dependency to your Cartfile:

binary "https://soulver.app/core/SoulverCore.json"

Supported Syntaxes

Explore Soulver's documentation for more information on supported syntaxes.

Apps using SoulverCore

Soulver - a popular notepad calculator for macOS
Lacona - a powerful natural language assistant/launcher for macOS
Toolbox Pro - calculate with Soulver as part of your Siri Shortcuts on iOS

Licence

You may use SoulverCore in personal/private projects. Please email us if you wish to use SoulverCore in a publicly available or commercial project.

rbarbera/SoulverCore