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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | 1x 1x 1x 1x 1x 1x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 901x 10x 10x 10x | import {Law, LawSet} from '#law'
import {Monad as MD} from '@effect/typeclass'
import {flow, pipe} from 'effect'
import type {TypeLambda} from 'effect/HKT'
import {covariantLaws} from './Covariant.js'
import {flatMapLaws} from './FlatMap.js'
import type {BuildParameterized} from './given.js'
import {unfoldGiven} from './given.js'
/**
* Typeclass laws for `Monad`.
* @category typeclass laws
*/
export const monadLaws: BuildParameterized<MonadTypeLambda> = (
given,
suffix?,
) => {
const {a, F, fa, equalsFa, equalsFb, ab, afb} = unfoldGiven(given)
return LawSet(covariantLaws(given), flatMapLaws(given))(
`Monad${suffix ?? ''}`,
Law(
'left identity',
'of ∘ flatMap(afb) = afb',
a,
afb,
)((a, afb) => equalsFb(pipe(a, F.of, F.flatMap(afb)), afb(a))),
Law(
'right identity',
'flatMap(of) = id',
fa,
)(fa => equalsFa(pipe(fa, F.flatMap(F.of)), fa)),
Law(
'map consistency',
'map(ab) = flatMap(of ∘ ab)',
fa,
ab,
)((fa, ab) =>
equalsFb(pipe(fa, F.map(ab)), pipe(fa, F.flatMap(flow(ab, F.of)))),
),
)
}
/**
* Type lambda for the `Monad` typeclass.
* @category type lambda
*/
export interface MonadTypeLambda extends TypeLambda {
readonly type: MD.Monad<this['Target'] & TypeLambda>
}
declare module './given.js' {
interface ParameterizedLambdas {
Monad: MonadTypeLambda
}
}
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