StdLib

The

StdLib module provides a set of standard libraries for common Expression patterns.

StdLib

OptionType

Ƭ OptionType<T>:

VariantType<{ none: NullType ; some: T }>

Return an EastType for the Option variant with cases "none" (indicating the lack of data) and "some" (indicating the presence of data).

This is an alias for VariantType({ none: NullType, some: type }).

Param

The EastType associated with the "some" case.

See

Some, Unwrap, None, MapOption.

Type parameters

Name	Type
T	extends EastType = EastType

---

None

• Const None: ConstFunction<

VariantType<{ none: NullType }>>

An EastFunction containing the "none" case of the Option variant. This is an alias for Const(none).

See

Some, Unwrap, MapOption, OptionType.

---

Abs

▸ Abs(x): EastFunction<

IntegerType>

Return the absolute value of a number or integer

Expression.

Parameters

Name	Type
x	Expression<IntegerType>

Returns

EastFunction<

IntegerType>

---

AddAll

▸ AddAll(collection): EastFunction<

FloatType>

Add all collection values into a single float or integer

Expression.

Parameters

Name	Type
collection	EastFunction<ArrayType<FloatType>>

Returns

EastFunction<

FloatType>

---

AddDict

▸ AddDict<T>(d1, d2): MapValuesFunction<

DictType<StringType, any>>

Add first to second where both are dictionaries.

Type parameters

Name	Type
T	extends NumericType

Parameters

Name	Type
d1	EastFunction<DictType<StringType, T>>
d2	EastFunction<DictType<StringType, T>>

Returns

MapValuesFunction<

DictType<StringType, any>>

Remarks

Missing keys between first and second are assumed to have a value of 0.

Example

 // ...
 // return the prices by dividing the total amounts by the qtys 
 NewBalance: AddDict(
     Variable('InitialBalance', DictType(StringType, FloatType)),
     Variable('Amount', DictType(StringType, FloatType))
 ),
 // ... 

---

Ceiling

▸ Ceiling<T>(value, unit): EastFunction<T>

Round datetime value up to a whole time unit ("year", "month", "week", "day", "hour", "minute", "second").

Type parameters

Name	Type
T	extends DateTimeType

Parameters

Name	Type
value	EastFunction<T>
unit	TimeUnit | CalendarUnit

Returns

EastFunction<T>

▸ Ceiling<T>(value, type?): EastFunction<T>

Round number value up to a whole number.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type?	"float"

Returns

EastFunction<T>

▸ Ceiling<T>(value, type?): EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

Round number value up to nearest integer.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type?	"integer"

Returns

EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

---

Compare

▸ Compare<T>(a, b): EastFunction<

IntegerType>

Comparison function between two expressions.

Type parameters

Name	Type
T	extends EastType

Parameters

Name	Type
a	Expression<T>
b	Expression<T>

Returns

EastFunction<

IntegerType>

---

ConvertFloatDict

▸ ConvertFloatDict(dict): EastFunction<

DictType<StringType, IntegerType>>

Convert a float

DictType to an integer DictType.

Parameters

Name	Type
dict	EastFunction<DictType<StringType, FloatType>>

Returns

EastFunction<

DictType<StringType, IntegerType>>

---

ConvertIntegerDict

▸ ConvertIntegerDict(dict): EastFunction<

DictType<StringType, FloatType>>

Convert an integer

DictType to an float DictType.

Parameters

Name	Type
dict	EastFunction<DictType<StringType, IntegerType>>

Returns

EastFunction<

DictType<StringType, FloatType>>

---

DateKey

▸ DateKey(value, unit?): EastFunction<

StringType>

Convenience function to convert a datetime into a string for a key, rounding optional.

Parameters

Name	Type
value	EastFunction<DateTimeType>
unit?	TimeUnit | CalendarUnit

Returns

EastFunction<

StringType>

---

DayInteger

▸ DayInteger(day_name): GetFunction<

IntegerType>

Return a

Print function to convert a day of week Expression to a day of week name.

Parameters

Name	Type
day_name	EastFunction<StringType>

Returns

GetFunction<

IntegerType>

---

DayName

▸ DayName(date): GetFunction<

StringType>

Return a

Print function to convert a datetime Expression to a day of week name.

Parameters

Name	Type
date	EastFunction<IntegerType | DateTimeType>

Returns

GetFunction<

StringType>

---

DayNameShort

▸ DayNameShort(date): GetFunction<

StringType>

Return a

Print function to convert a datetime Expression to an abbreviated day of week name.

Parameters

Name	Type
date	EastFunction<IntegerType | DateTimeType>

Returns

GetFunction<

StringType>

---

FilterTag

▸ FilterTag<T, Tag, K>(collection, tag): EastFunction<

DictType<K, T["value"][Tag]>>

Filter and map a collection (array or dictionary) of variants, keeping just one variant case (or tag) and unwrapping the associated data.

Type parameters

Name	Type
T	extends VariantType
Tag	extends string | number | symbol
K	extends StringType

Parameters

Name	Type	Description
collection	EastFunction<DictType<K, T>>	an Expression for a collection of variants
tag	Tag	the variant case (or tag) to keep and unwrap

Returns

EastFunction<

DictType<K, T["value"][Tag]>>

---

Floor

▸ Floor<T>(value, unit): EastFunction<T>

Round datetime value down to a whole time unit ("year", "month", "week", "day", "hour", "minute", "second").

Type parameters

Name	Type
T	extends DateTimeType

Parameters

Name	Type
value	EastFunction<T>
unit	TimeUnit | CalendarUnit

Returns

EastFunction<T>

▸ Floor<T>(value, type): EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

Round number value down to nearest integer

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type	"integer"

Returns

EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

▸ Floor<T>(value, type?): EastFunction<T>

Round number value down to a whole number.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type?	"float"

Returns

EastFunction<T>

---

GetTag

▸ GetTag<Variants, Fs>(value): EastFunction<

StringType>

Returns a

StringType EastFunction for the tag of a VariantType EastFunction.

Type parameters

Name	Type
Variants	extends Record<string, EastType>
Fs	extends { [K in string | number | symbol]: Function }

Parameters

Name	Type	Description
value	EastFunction<VariantType<Variants>>	An EastFunction for the Option variant.

Returns

EastFunction<

StringType>

---

HasTag

▸ HasTag<T, Tag>(value, tag): EastFunction<

BooleanType>

Returns a

BooleanType to determine if the tag of a VariantType EastFunction matches a supplied value.

Type parameters

Name	Type
T	extends VariantType
Tag	extends string | number | symbol

Parameters

Name	Type	Description
value	EastFunction<T>	An EastFunction for the Option variant.
tag	Tag	the variant case (or tag) to test against

Returns

EastFunction<

BooleanType>

---

Importance

▸ Importance(domain, range?): EastFunction<

StringType>

Convert a number

Expression to a magnitude string between ['negligible', 'moderate', 'large'].

Parameters

Name	Type
domain	Expression<FloatType>
range	[negligible: number, moderate: number]

Returns

EastFunction<

StringType>

---

IsEmpty

▸ IsEmpty(collection): EastFunction<

BooleanType>

Return true if collection has zero elements, or false otherwise.

Parameters

Name	Type
collection	EastFunction<SetType | DictType>

Returns

EastFunction<

BooleanType>

---

IsFriday

▸ IsFriday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Friday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsMonday

▸ IsMonday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Monday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsNotNull

▸ IsNotNull(value): EastFunction<

BooleanType>

Return true if value is null or false otherwise.

Parameters

Name	Type
value	EastFunction<EastType>

Returns

EastFunction<

BooleanType>

---

IsNull

▸ IsNull(value): EastFunction<

BooleanType>

Return true if value is null or false otherwise.

Parameters

Name	Type
value	EastFunction<EastType>

Returns

EastFunction<

BooleanType>

---

IsSaturday

▸ IsSaturday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Saturday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsSunday

▸ IsSunday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Sunday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsThursday

▸ IsThursday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Thursday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsTuesday

▸ IsTuesday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Tuesday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsWednesday

▸ IsWednesday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a Wednesday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsWeekday

▸ IsWeekday(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a weekday.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

IsWeekend

▸ IsWeekend(date): EastFunction<

BooleanType>

Return the a boolean function to determine if a datetime

Expression falls on a weekend.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

BooleanType>

---

MapOption

▸ MapOption<T, F>(value, f): EastFunction<

OptionType<ReturnType<F>["type"]>>

Returns an EastFunction to map the data corresponding to the "some" case an Option variant through a function, while leaving the "none" case alone.

Type parameters

Name	Type
T	extends EastType
F	extends (data: Variable<T>) => EastFunction

Parameters

Name	Type	Description
value	EastFunction<OptionType<T>>	An EastFunction for the Option variant.
f	F	A function of data associated with the "some" case returning an EastFunction for the new associated data.

Returns

EastFunction<

OptionType<ReturnType<F>["type"]>>

See

None, Some, Unwrap, OptionType.

---

MatchTag

▸ MatchTag<T, Tag, R, Fs>(value, tag, f, defaultValue): EastFunction<R>

Returns a EastType to based on provided tag of a

VariantType EastFunction.

Type parameters

Name	Type
T	extends VariantType
Tag	extends string | number | symbol
R	extends EastType
Fs	extends (v: Variable<T["value"][Tag]>) => EastFunction<R>

Parameters

Name	Type	Description
value	EastFunction<T>	An EastFunction for the Option variant.
tag	Tag	the variant case (or tag) to test against
f	Fs	the expression of the variant value
defaultValue	EastFunction<R>	the default value when the variant doesn't hag the tag

Returns

EastFunction<R>

---

Max

▸ Max<T, U>(a, b): EastFunction<U>

Return the greater of a and b (note that null and NaN are greater than every other value).

Type parameters

Name	Type
T	extends PrimitiveType
U	extends PrimitiveType

Parameters

Name	Type
a	Expression<U>
b	Expression<T>

Returns

EastFunction<U>

---

Min

▸ Min<T, U>(a, b): EastFunction<U>

Return the lesser of a and b (note that null and NaN are greater than every other value).

Type parameters

Name	Type
T	extends PrimitiveType
U	extends PrimitiveType

Parameters

Name	Type
a	Expression<U>
b	Expression<T>

Returns

EastFunction<U>

---

MonthNameShort

▸ MonthNameShort(date): GetFunction<

StringType>

Return a

Print function to convert a datetime Expression to an abbreviated month name.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

GetFunction<

StringType>

---

MultiplyDict

▸ MultiplyDict<X, Y>(first, second): EastFunction<

DictType<StringType, PromoteType<X, Y>>>

Multiply first by second where both are dictionaries.

Type parameters

Name	Type
X	extends IntegerType | FloatType
Y	extends IntegerType | FloatType

Parameters

Name	Type	Description
first	Expression<DictType<StringType, X>>	the first Expression to multiply
second	Expression<DictType<StringType, Y>>	the second Expression to multiply

Returns

EastFunction<

DictType<StringType, PromoteType<X, Y>>>

Example

 // ...
 // return the products revenue by multiplying the prices by the qtys
 Amounts: MultiplyDict(
     Variable('UnitPrices', DictType(StringType, FloatType)),
     Variable('Quantities', DictType(StringType, FloatType))
 ),
 // ... 

---

OptionType

▸ OptionType<T>(type):

VariantType<{ none: NullType = NullType; some: T = type }>

Return an EastType for the option variant with cases "none" (indicating the lack of data) and "some" (indicating the presence of data).

This is an alias for VariantType({ none: NullType, some: type }).

Type parameters

Name	Type
T	extends EastType

Parameters

Name	Type	Description
type	T	The EastType associated with the "some" case.

Returns

VariantType<{ none: NullType = NullType; some: T = type }>

See

Some, Unwrap, MapOption, Option.

---

PadEnd

▸ PadEnd(value, char, n): EastFunction<

StringType>

Pad the end of a string with a character up to a certain total length.

Parameters

Name	Type
value	EastFunction<StringType>
char	string | EastFunction<StringType>
n	bigint | EastFunction<IntegerType>

Returns

EastFunction<

StringType>

Remarks

it is assumed that char has length 1.

---

PadStart

▸ PadStart(value, char, n): EastFunction<

StringType>

Pad the start of a string with a character up to a certain total length.

Parameters

Name	Type
value	EastFunction<StringType>
char	string | EastFunction<StringType>
n	bigint | EastFunction<IntegerType>

Returns

EastFunction<

StringType>

Remarks

it is assumed that char has length 1.

---

PrimaryKey

▸ PrimaryKey(...values): EastFunction<

StringType>

Convenience function to convert one or more expressions into a string for a key.

Parameters

Name	Type
...values	EastFunction<PrimitiveType>[]

Returns

EastFunction<

StringType>

---

PrintSeperated

▸ PrintSeperated(x, thousands_seperator): EastFunction<

StringType>

Print a number with a seperator between the thousands, e.g. 1234 as "1,234"

Parameters

Name	Type
x	Expression<IntegerType | FloatType>
thousands_seperator	string

Returns

EastFunction<

StringType>

---

PrintTruncatedCurrency

▸ PrintTruncatedCurrency(value): EastFunction<

StringType>

Return a comma seperated and rounded currency string from an integer.

Parameters

Name	Type
value	Expression<IntegerType>

Returns

EastFunction<

StringType>

▸ PrintTruncatedCurrency(value): EastFunction<

StringType>

Return a comma seperated and rounded currency string from a number.

Parameters

Name	Type
value	Expression<FloatType>

Returns

EastFunction<

StringType>

---

RandomExponential

▸ RandomExponential(): EastFunction<

FloatType>

Return a random number drawn from an exponential distribution.

Returns

EastFunction<

FloatType>

---

RandomKeys

▸ RandomKeys<T>(collection, n): EastFunction<

SetType<T>>

Return a random subset of at most n keys from the input collection.

Type parameters

Name	Type
T	extends StringType

Parameters

Name	Type
collection	EastFunction<DictType<T>>
n	EastFunction<IntegerType>

Returns

EastFunction<

SetType<T>>

---

RandomValues

▸ RandomValues<I>(collection, n): EastFunction<

DictType<StringType, I>>

Return a random subset of at most n values from the input collection (using sampling without replacement).

Type parameters

Name	Type
I	extends EastType

Parameters

Name	Type
collection	EastFunction<DictType<StringType, I>>
n	EastFunction<IntegerType>

Returns

EastFunction<

DictType<StringType, I>>

---

RandomWeibull

▸ RandomWeibull(shape): EastFunction<

FloatType>

Return a random number drawn from the Weibull distribution.

Parameters

Name	Type
shape	EastFunction<FloatType>

Returns

EastFunction<

FloatType>

---

Replace

▸ Replace<T, U, V>(value, from, to): EastFunction<T>

Return value unless it equals from, in which case replace it with to.

Type parameters

Name	Type
T	extends PrimitiveType
U	extends PrimitiveType
V	extends PrimitiveType

Parameters

Name	Type
value	EastFunction<T>
from	Expression<U>
to	Expression<V>

Returns

EastFunction<T>

---

RoundMultiple

▸ RoundMultiple<T>(value, divisor, rounding_mode?): EastFunction<T extends

NullType ? Nullable<T> : T>

Round number value up to nearest multiple of divisor.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
divisor	EastFunction<T>
rounding_mode?	RoundingMode

Returns

EastFunction<T extends

NullType ? Nullable<T> : T>

---

SetField

▸ SetField<T, Name>(struct, name, value): EastFunction<T>

Update an existing field of a struct to a value of the same type.

Type parameters

Name	Type
T	extends StructType
Name	extends string | number | symbol

Parameters

Name	Type
struct	EastFunction<T>
name	Name
value	EastFunction<T["value"][Name]>

Returns

EastFunction<T>

See

Struct, Spread

---

Sigmoid

▸ Sigmoid<T>(x): EastFunction<T>

Return a number EastFunction to peform ...

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
x	EastFunction<T>

Returns

EastFunction<T>

---

Some

▸ Some<T>(data): VariantFunction<

VariantType<{ some: T }>>

Returns an EastFunction to construct the "some" case of the Option variant with associated data. This is an alias for Variant("some", value).

Type parameters

Name	Type
T	extends EastType

Parameters

Name	Type	Description
data	EastFunction<T>	An EastFunction containing the associated data.

Returns

VariantFunction<

VariantType<{ some: T }>>

See

None, Unrwap, MapOption, OptionType, some.

---

Spread

▸ Spread<T>(x): { [K in keyof T["value"]]: EastFunction<T["value"][K]> }

A helper function to assist in creating large structs. It works identically to how object spreading works in JavaScript. You can use it to either update existing fields in a struct, or to add new fields to a struct.

Type parameters

Name	Type
T	extends StructType

Parameters

Name	Type
x	EastFunction<T>

Returns

{ [K in keyof T["value"]]: EastFunction<T["value"][K]> }

See

Struct, SetField

Example

// build a struct with an additional field called new_field.
vars => Struct({ ...Spread(vars.large_struct), new_field: new_value })

---

ToEntries

▸ ToEntries<T>(dict): EastFunction<

ArrayType<StructType<{ Key: StringType ; Value: T }>>>

Return a

ArrayType EastFunction to convert a dictionary into an array of key & value pairs

Type parameters

Name	Type
T	extends EastType

Parameters

Name	Type
dict	EastFunction<DictType<StringType, T>>

Returns

EastFunction<

ArrayType<StructType<{ Key: StringType ; Value: T }>>>

---

Truncate

▸ Truncate<T>(value, type?): EastFunction<T>

Round number value towards zero to a whole number.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type?	"float"

Returns

EastFunction<T>

▸ Truncate<T>(value, type?): EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

Round number value towards zero to the nearest integer.

Type parameters

Name	Type
T	extends FloatType

Parameters

Name	Type
value	EastFunction<T>
type?	"integer"

Returns

EastFunction<T extends

NullType ? Nullable<IntegerType> : IntegerType>

---

UnionAll

▸ UnionAll<T>(collection): EastFunction<T>

Union all sets in collection into a single set

Expression.

Type parameters

Name	Type
T	extends SetType

Parameters

Name	Type
collection	EastFunction<ArrayType<T> | DictType<StringType, T>>

Returns

EastFunction<T>

---

Unwrap

▸ Unwrap<T, U>(value, defaultValue): EastFunction<T & U>

Returns an EastFunction to unwrap an Option variant, replacing the "none" case with defaultValue.

Type parameters

Name	Type
T	extends EastType
U	extends EastType

Parameters

Name	Type	Description
value	EastFunction<OptionType<T>>	An EastFunction for the Option variant.
defaultValue	EastFunction<U>	An EastFunction containing the associated data.

Returns

EastFunction<T & U>

See

None, Some, MapOption, OptionType.

---

WeekDescription

▸ WeekDescription(cycle): EastFunction<

StringType>

Return a

Print function to convert a cycle Expression to an abbreviated week description.

Parameters

Name	Type
cycle	EastFunction<IntegerType>

Returns

EastFunction<

StringType>

---

WeekOfMonth

▸ WeekOfMonth(date): EastFunction<

IntegerType>

Return the number of whole weeks elapsed since the first Monday prior to or of the first day of the month.

Parameters

Name	Type
date	EastFunction<DateTimeType>

Returns

EastFunction<

IntegerType>