memo

Memoize a function

Usage

Wrap a function with memo to get a function back that automagically returns values that have already been calculated.

import * as 
import _
_ from 'radashi'

const 
const timestamp: () => number
timestamp = 
import _
_.
function memo<[], number>(func: () => number, options?: _.MemoOptions<[]>): () => number
Creates a memoized function. The returned function will only
execute the source function when no value has previously been
computed. If a ttl (milliseconds) is given previously computed
values will be checked for expiration before being returned.
@see ― https://radashi.js.org/reference/curry/memo
@example 
const calls: number[] = []
const fib = memo((x: number) => {
  calls.push(x)
  return x < 2 ? x : fib(x - 1) + fib(x - 2)
})

fib(10) // 55
fib(10) // 55
// calls === [10]

fib(11) // 89
// calls === [10, 11]
@version ― 12.1.0
memo(() => 
var Date: DateConstructor
Enables basic storage and retrieval of dates and times.
Date.
DateConstructor.now(): number
Returns the number of milliseconds elapsed since midnight, January 1, 1970 Universal Coordinated Time (UTC).
now())

const 
const now: number
now = 
const timestamp: () => number
timestamp()
const 
const later: number
later = 
const timestamp: () => number
timestamp()

const now: number
now === 
const later: number
later // => true

Expiration

You can optionally pass a ttl (time to live) that will expire memoized results. In versions prior to version 10, ttl had a value of 300 milliseconds if not specified.

import * as 
import _
_ from 'radashi'

const 
const timestamp: () => number
timestamp = 
import _
_.
function memo<[], number>(func: () => number, options?: _.MemoOptions<[]>): () => number
Creates a memoized function. The returned function will only
execute the source function when no value has previously been
computed. If a ttl (milliseconds) is given previously computed
values will be checked for expiration before being returned.
@see ― https://radashi.js.org/reference/curry/memo
@example 
const calls: number[] = []
const fib = memo((x: number) => {
  calls.push(x)
  return x < 2 ? x : fib(x - 1) + fib(x - 2)
})

fib(10) // 55
fib(10) // 55
// calls === [10]

fib(11) // 89
// calls === [10, 11]
@version ― 12.1.0
memo(() => 
var Date: DateConstructor
Enables basic storage and retrieval of dates and times.
Date.
DateConstructor.now(): number
Returns the number of milliseconds elapsed since midnight, January 1, 1970 Universal Coordinated Time (UTC).
now(), {
  
MemoOptions<TArgs extends any[]>.ttl?: number
ttl: 1000, // milliseconds
})

const 
const now: number
now = 
const timestamp: () => number
timestamp()
const 
const later: number
later = 
const timestamp: () => number
timestamp()

await 
import _
_.
function sleep(milliseconds: number): Promise<void>
Create a promise that resolves after a given amount of time.
@see ― https://radashi.js.org/reference/async/sleep
@example 
await sleep(1000)
@version ― 12.1.0
sleep(2000)

const 
const muchLater: number
muchLater = 
const timestamp: () => number
timestamp()

const now: number
now === 
const later: number
later // => true
const now: number
now === 
const muchLater: number
muchLater // => false

Key Function

You can optionally customize how values are stored when memoized.

const 
const timestamp: (args_0: {
    group: string;
}) => string
timestamp = 
import _
_.
function memo<[{
    group: string;
}], string>(func: (args_0: {
    group: string;
}) => string, options?: _.MemoOptions<[{
    group: string;
}]>): (args_0: {
    group: string;
}) => string
Creates a memoized function. The returned function will only
execute the source function when no value has previously been
computed. If a ttl (milliseconds) is given previously computed
values will be checked for expiration before being returned.
@see ― https://radashi.js.org/reference/curry/memo
@example 
const calls: number[] = []
const fib = memo((x: number) => {
  calls.push(x)
  return x < 2 ? x : fib(x - 1) + fib(x - 2)
})

fib(10) // 55
fib(10) // 55
// calls === [10]

fib(11) // 89
// calls === [10, 11]
@version ― 12.1.0
memo(
  ({ 
group: string
group }: { 
group: string
group: string }) => {
    const 
const ts: number
ts = 
var Date: DateConstructor
Enables basic storage and retrieval of dates and times.
Date.
DateConstructor.now(): number
Returns the number of milliseconds elapsed since midnight, January 1, 1970 Universal Coordinated Time (UTC).
now()
    return `${
const ts: number
ts}::${
group: string
group}`
  },
  {
    
MemoOptions<[{ group: string; }]>.key?: (args_0: {
    group: string;
}) => string
key: ({ 
group: string
group }: { 
group: string
group: string }) => 
group: string
group,
  },
)

const 
const now: string
now = 
const timestamp: (args_0: {
    group: string;
}) => string
timestamp({ 
group: string
group: 'alpha' })
const 
const later: string
later = 
const timestamp: (args_0: {
    group: string;
}) => string
timestamp({ 
group: string
group: 'alpha' })
const 
const beta: string
beta = 
const timestamp: (args_0: {
    group: string;
}) => string
timestamp({ 
group: string
group: 'beta' })

const now: string
now === 
const later: string
later // => true
const beta: string
beta === 
const now: string
now // => false