gcantiAdapted from purescript-logging
fp-ts and TypeScript compatibility
logging-ts version |
required fp-ts version |
required TypeScript version |
|---|---|---|
| 0.3.0 | 2.0.0+ | 3.5+ |
| 0.2.0 | 1.7.0+ | 2.8.0+ |
Usage
From purescript-logging's README
A logger receives records and potentially performs some effects. You can create a logger from any function
(a: A) => HKT<M, void>for anyAandM.Unlike most other logging libraries,
logging-tshas no separate concepts "loggers" and "handlers". Instead, loggers can be composed into larger loggers using theSemigroupinstance. Loggers can also be transformed usingcontramap(for transforming records) andfilter(for filtering records). An example use case might be the following:
import * as C from 'fp-ts/lib/Console'
import * as D from 'fp-ts/lib/Date'
import { chain, IO } from 'fp-ts/lib/IO'
import { pipe } from 'fp-ts/lib/pipeable'
import * as L from '../src/IO'
type Level = 'Debug' | 'Info' | 'Warning' | 'Error'
interface Entry {
message: string
time: Date
level: Level
}
function showEntry(entry: Entry): string {
return `[${entry.level}] ${entry.time.toLocaleString()} ${entry.message}`
}
function getLoggerEntry(prefix: string): L.LoggerIO<Entry> {
return entry => C.log(`${prefix}: ${showEntry(entry)}`)
}
const debugLogger = L.filter(getLoggerEntry('debug.log'), e => e.level === 'Debug')
const productionLogger = L.filter(getLoggerEntry('production.log'), e => e.level !== 'Debug')
const logger = L.getMonoid<Entry>().concat(debugLogger, productionLogger)
const info = (message: string) => (time: Date): IO<void> => logger({ message, time, level: 'Info' })
const debug = (message: string) => (time: Date): IO<void> => logger({ message, time, level: 'Debug' })
const program = pipe(
D.create,
chain(info('boot')),
chain(() => D.create),
chain(debug('Hello!'))
)
program()
/*
production.log: [Info] 10/4/2019, 12:44:48 PM boot
debug.log: [Debug] 10/4/2019, 12:44:48 PM Hello!
*/