48 lines
1.3 KiB
JavaScript
48 lines
1.3 KiB
JavaScript
// @ts-nocheck
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import { it, assert } from 'folktest'
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import { IO, List, Option, Reader, Result, Some } from '../../src/index.js'
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import { Applicative, Chain, Ord, Setoid } from '../../src/algebra/interfaces.js'
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const Algebra = [Option, Result, List, IO, Reader]
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const inc = F => x => F.of(x + 1)
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const dbl = F => x => F.of(x * 2)
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const impl = i => m => i.implementedBy(m)
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export const Tests = [
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it('unit is a left identity', () => {
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Algebra.filter(impl(Setoid, Applicative, Chain)).forEach(algebra => {
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const f = inc(algebra)
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assert(
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algebra.of(1).chain(f).equals(f(1)),
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`${algebra.name} is not a left identity`
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)
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})
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}),
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it('unit is a right identity', () => {
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Algebra.filter(impl(Setoid, Applicative, Chain)).forEach(algebra => {
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const m = algebra.of(1)
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assert(
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m.chain(algebra.of).equals(m),
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`${algebra.name} is not a right identity`
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)
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})
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}),
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it('unit is associative', () => {
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Algebra.filter(impl(Setoid, Applicative, Chain)).forEach(algebra => {
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const a = algebra.of(1)
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const f = inc(algebra)
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const g = dbl(algebra)
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const x = a.chain(f).chain(g)
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const y = a.chain(x => f(x).chain(g))
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assert(x.equals(y), `${algebra.name} is not associative`)
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})
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}),
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]
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