Taxi StdLib

Taxi ships with a collections of functions for basic operations on data.

These operations are performed locally on data received from services - it does not instruct remote services to perform these changes.

Taxi does not provide implementations of these functions, that’s left to runtimes, such as Orbital.

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Strings

A collection of functions for manipulating strings

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applyFormat

taxi.stdlib.applyFormat

declare extension function applyFormat(input: Any, format: String):String

Applies the provided format to the input string, and returns the result.

Formats follow the format defined by the Java Formatter conventions

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concat

taxi.stdlib.concat

declare function concat(Any...):String

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containsString

taxi.stdlib.containsString

declare extension function containsString(source:String, valueToSearchFor:String):Boolean

Returns true if valueToSearchFor within source

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indexOf

taxi.stdlib.indexOf

declare extension function indexOf(source:String, valueToSearchFor:String):Int

Returns the index of valueToSearchFor within source

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left

taxi.stdlib.left

declare extension function left(source:String,count:Int):String

Returns the left most characters from the source string

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length

taxi.stdlib.length

declare extension function length(String):Int

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lowerCase

taxi.stdlib.lowerCase

declare extension function lowerCase(String):String

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mid

taxi.stdlib.mid

declare extension function mid(source: String,startIndex: Int,endIndex: Int):String

Returns the middle of a string, starting at the startIndex, and ending right before the endIndex.

• startIndex - the start index (inclusive)
• endIndex - the end index (exclusive)

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padEnd

taxi.stdlib.padEnd

declare extension function padEnd(input: String, length: Int, padWith: String):String

Pads the string to the specified length at the end with the specified character or space. padWith should be a single character - if multiple characters are passed, only the first is used

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padStart

taxi.stdlib.padStart

declare extension function padStart(input: String, length: Int, padWith: String):String

Pads the string to the specified length at the start with the specified character or space. padWith should be a single character - if multiple characters are passed, only the first is used

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replace

taxi.stdlib.replace

declare extension function replace(source: String, searchValue:String, replacement: String):String

Replaces the contents of the provided String, returning a new String Accepts three args:

• source: String: The string to search
• searchValue: String: The string to search for
• replacement: String: The string to use as a replacement

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right

taxi.stdlib.right

declare extension function right(source:String,count:Int):String

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trim

taxi.stdlib.trim

declare extension function trim(String):String

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upperCase

taxi.stdlib.upperCase

declare extension function upperCase(String):String

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Collections

A collection of functions for operating on collections

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all

taxi.stdlib.all

declare extension function <T> all(collection: T[], predicate: (T) -> Boolean): Boolean

Returns true if all of the items in the collection satisfy the predicate

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allOf

taxi.stdlib.allOf

declare function allOf(values:Boolean...): Boolean

Returns true only if all provided boolean values are true. Equivalent to logical AND.

This function ensures that every condition in a set must be satisfied.

// Check if a user can purchase a premium item
type CanPurchasePremium inherits Boolean by allOf(IsActive, HasSufficientFunds, IsVerified)

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Examples

This example demonstrates how to use allOf() to verify if a user meets all required criteria for premium access.

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any

taxi.stdlib.any

declare extension function <T> any(collection: T[], predicate: (T) -> Boolean): Boolean

Returns true if any of the items in the collection satisfy the predicate

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anyOf

taxi.stdlib.anyOf

declare function anyOf(values:Boolean...): Boolean

Returns true if at least one of the provided boolean values is true. Equivalent to logical OR.

This function evaluates multiple conditions and returns true if any of them are true.

// Check if a user has any account verification
type IsVerified inherits Boolean by anyOf(HasEmailVerification, HasPhoneVerification, HasIdVerification)

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Examples

This example demonstrates how to use anyOf() to verify if a user meets any of several verification criteria.

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contains

taxi.stdlib.contains

declare extension function <T> contains(collection: T[], searchTarget:T): Boolean

Returns true if the collection contains the specified search target element.

This function checks whether a given element exists within an array or collection.

// Check if a user's roles include admin privileges
find { user: User } as {
   hasAdminAccess: user.roles.contains("ADMIN")
}

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Examples

This example demonstrates how to use contains() to check if a user has a specific role.

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exactlyOne

taxi.stdlib.exactlyOne

declare extension function <T> exactlyOne(collection:T[]):T

Returns the only item from the provided collection, or throws an error if there isn’t exactly one item in the collection.

This function is useful when you expect a collection to contain precisely one element and want to retrieve it.

// Get the single active session for a user
find { user: User } as {
   currentSession: user.sessions.filter((session) -> session.isActive).exactlyOne()
}

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Examples

This example demonstrates how to use exactlyOne() to retrieve the single active session for a user.

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filter

taxi.stdlib.filter

declare extension function <T> filter(collection:T[], callback: (T) -> Boolean):T[]

Returns a new collection containing only the members of the original collection that match the provided predicate.

This function is used to select a subset of elements from a collection based on a condition.

find { store: Store } as {
   allProducts: store.products // all products
   inStockProducts: store.products.filter((product) -> product.stockLevel > 0)
   affordableProducts: store.products.filter((product) -> product.price < 50.00)
}

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Examples

This example demonstrates how to use filter() to find friends who meet a certain age criteria.

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filterEach

taxi.stdlib.filterEach

declare extension function <T> filterEach(item: T, callback: (T) -> Boolean):T?

Evaluates the predicate against the provided item, returning the item if the predicate returns true, or null otherwise.

This function is intended for use in filtering streams, where null values are automatically excluded.

// Filter individual items in a pipeline
find { items: Item[] } as {
   processedItems: items.map((item) -> filterEach(item, (i) -> i.status == "READY"))
}

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Examples

This example demonstrates how to use filterEach() to process items in a stream-like manner, keeping only those that meet certain criteria.

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first

taxi.stdlib.first

declare extension function <T> first(collection: T[]):T

Returns the first item within the collection. Throws an error if the collection is empty.

This function retrieves the first element in an ordered collection.

// Get the most recent transaction from a sorted list
find { account: Account } as {
   latestTransaction: account.transactions.first()
}

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Examples

This example demonstrates how to use first() to retrieve the most recent transaction for an account.

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getAtIndex

taxi.stdlib.getAtIndex

declare extension function <T> getAtIndex(collection: T[], index: Int):T

Returns the item at the provided index in the collection. Throws an error if the index is out of bounds.

This function retrieves an element at a specific position in a collection, with zero-based indexing.

// Get the second item in a list
find { playlist: Playlist } as {
   secondSong: playlist.songs.getAtIndex(1) // Note: index starts at 0
}

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Examples

This example demonstrates how to use getAtIndex() to retrieve a specific song from a playlist by its position.

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intersection

taxi.stdlib.intersection

declare extension function <T> intersection(collectionA: T[], collectionB: T[]):T[]

Returns a new collection containing only the elements that are present in both of the provided collections.

This function identifies common elements between two collections.

// Find common tags between two products
find { productA: Product, productB: Product } as {
   commonTags: intersection(productA.tags, productB.tags)
}

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Examples

This example demonstrates how to use intersection() to find common elements between two collections.

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joinToString

taxi.stdlib.joinToString

declare extension function <T> joinToString(values:T[], separator: String = ",", prefix: String? = null, postfix: String? = null): String

Creates a string from all the elements separated using separator and using the given prefix and postfix if supplied. Null values are omitted

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last

taxi.stdlib.last

declare extension function <T> last(collection: T[]):T

Returns the last item within the collection. Throws an error if the collection is empty.

This function retrieves the final element in an ordered collection.

// Get the oldest transaction from a date-sorted list
find { account: Account } as {
   oldestTransaction: account.transactions.last()
}

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Examples

This example demonstrates how to use last() to retrieve the oldest transaction for an account.

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listOf

taxi.stdlib.listOf

declare function <T> listOf(values:T...):T[]

Creates and returns an array containing all the provided values.

This function is useful for creating collections inline without having to define them separately.

// Create a list of allowed status values
find { order: Order } as {
   isValidStatus: listOf('PENDING', 'PROCESSING', 'SHIPPED', 'DELIVERED').contains(order.status)
}

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Examples

This example demonstrates how to use listOf() to create an inline collection and validate against it.

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none

taxi.stdlib.none

declare extension function <T> none(collection: T[], predicate: (T) -> Boolean): Boolean

Returns true if none of the items in the collection satisfy the predicate

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noneOf

taxi.stdlib.noneOf

declare function noneOf(values:Boolean...): Boolean

Returns true only if all provided boolean values are false. Equivalent to logical NOR.

This function is useful for checking if none of multiple conditions apply.

// Check if a user has no permissions
type NoPermissions inherits Boolean by noneOf(IsAdmin, IsEditor, IsViewer)

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Examples

This example demonstrates how to use noneOf() to verify if a user lacks all specified roles.

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single

taxi.stdlib.single

declare extension function <T> single(collection:T[], callback: (T) -> Boolean):T

Returns the first item from a collection that matches the provided predicate. Throws an error if no matching item is found.

This function is useful when you need to find a specific element in a collection based on a condition.

// Find a product by its SKU code
find { inventory: Inventory } as {
   appleMacbook: inventory.products.single((product) -> product.sku == "MB-PRO-2023")
}

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Examples

This example demonstrates how to use single() to find a specific product in an inventory.

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singleBy

taxi.stdlib.singleBy

declare extension function <T,A> singleBy(collection:T[], groupingFunction: (T) -> A, searchValue: A):T

Returns the item from a collection where the value returned by the grouping function matches the search value.

Similar to single(), but results are first grouped by the selector function, and these results are cached to improve future performance when querying the same collection multiple times.

// Find a product by its SKU code using a cached search
find { inventory: Inventory } as {
   appleMacbook: inventory.products.singleBy((product) -> product.sku, "MB-PRO-2023")
}

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Examples

This example demonstrates how to use singleBy() to efficiently find items in a collection by a specific property.

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Dates

Mess about with time. Flux capacitor not included

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addDays

taxi.stdlib.dates.addDays

declare function <T> addDays(T, Int):T

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addMinutes

taxi.stdlib.dates.addMinutes

declare function <T> addMinutes(T, Int):T

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addSeconds

taxi.stdlib.dates.addSeconds

declare function <T> addSeconds(T, Int):T

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currentDate

taxi.stdlib.dates.currentDate

declare function currentDate():Date

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currentDateTime

taxi.stdlib.dates.currentDateTime

declare function currentDateTime():DateTime

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currentTime

taxi.stdlib.dates.currentTime

declare function currentTime():Time

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now

taxi.stdlib.dates.now

declare function now():Instant

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parseDate

taxi.stdlib.dates.parseDate

declare function <T> parseDate(String):T

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Math

Numbers ‘n’ such. Maths for the brits.

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max

taxi.stdlib.max

declare extension function <T,A> max(collection: T[], callback: (T) -> A):A

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min

taxi.stdlib.min

declare extension function <T,A> min(collection: T[], callback: (T) -> A):A

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round

taxi.stdlib.round

declare extension function round(value: Decimal, precision: Int = 0): Decimal

Rounds a decimal value to the specified precision.

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sum

taxi.stdlib.sum

declare extension function <T,A> sum(collection: T[], callback: (T) -> A):A

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Objects

Utilities for dealing with equality, etc

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equals

taxi.stdlib.equals

declare extension function <A,B> equals(a:A, b:B): Boolean

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Enums

Utilities for enums

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enumForName

taxi.stdlib.enumForName

declare extension function <T> enumForName(enumType: lang.taxi.Type<T>, enumName: String): T

Returns the enum value for the provided name

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hasEnumNamed

taxi.stdlib.hasEnumNamed

declare extension function <T> hasEnumNamed(enumType: lang.taxi.Type<T>, enumName: String): Boolean

Indicates if the enum contains an entry for the provided key.

Ignores default entries, so an enum with a default will return false to enumContains() if the key isn’t explicitly defined.

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Aggregations

Functions for aggregating data within transformations.

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sumOver

vyne.aggregations.sumOver

declare query function sumOver(Any...):Decimal

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Functional

Functions that are functionally functions. Funky

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fold

taxi.stdlib.fold

declare extension function <T,A> fold(collection: T[], initial: A, callback: (T,A) -> A):A

Iterates over a collection, combining elements to produce a single accumulated result.

Example:

// Given:
model Entry {
   weight:Weight inherits Int
   score:Score inherits Int
}

type WeightedAverage by (Entry[]) -> Entry[].fold(0, (Entry, Int) -> Int + (Weight*Score))

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map

taxi.stdlib.map

declare extension function <T,A> map(collection: T[], callback: (T) -> A):A[]

Performs a mapping transformation function on every member of the provided array.

If the callback is in the form of a type expression, then each input value is converted into an instance of that type.

For example:

// Will convert Person[] to Person2[]
Person[].map((Person) -> Person2)

If the callback is in the form of any other type of expression, then that expression is evaluated against each member of the input array.

For example:

// Will return an array of Title, where the text has been converted to uppercase
Film[].map ( (Title) -> Title.upperCase() )

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reduce

taxi.stdlib.reduce

declare extension function <T,A> reduce(collection: T[], callback: (T,A) -> A):A

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Transformations

Functions for converting between types

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convert

taxi.stdlib.convert

declare extension function <T> convert(source: Any, targetType: lang.taxi.Type<T>): T

Converts the provided source into the target type reference. Conversions are performed locally, using only the data provided in source - ie., no services or graph searches are performed.

This method is less powerful than using a standard projection (eg., A as B), because:

• Only the exact facts passed in the source are considered

• No graph searches or remote invocations are performed

  As a result, it’s also more performant.

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toRawType

taxi.stdlib.toRawType

declare extension function toRawType(source: Any):Any

Removes the semantic typing from the provided scalar value, returning a scalar value typed with the raw primitive type.

This can be useful if trying to compare values ignoring their type.

• If called with an Array, will remove semantic types of all members. The array should only contain scalar values.
• If called with a scalar value, will remove the semantic type of the value

Not supported for calling on an object (or array of objects), as Taxi’s type system is structural, and needs to know the structure of the type it’s operating on.

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Errors

Functions for creating and handling errors

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throw

taxi.stdlib.throw

declare function throw(error:Any):Nothing