mirror of
https://github.com/IBM/fp-go.git
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85 lines
2.0 KiB
Go
85 lines
2.0 KiB
Go
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package testing
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import (
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"testing"
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E "github.com/ibm/fp-go/eq"
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F "github.com/ibm/fp-go/function"
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L "github.com/ibm/fp-go/internal/apply/testing"
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"github.com/stretchr/testify/assert"
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)
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// Chain associativity law
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//
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// F.chain(F.chain(fa, afb), bfc) <-> F.chain(fa, a => F.chain(afb(a), bfc))
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func AssertAssociativity[HKTA, HKTB, HKTC, A, B, C any](t *testing.T,
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eq E.Eq[HKTC],
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fofa func(A) HKTA,
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fofb func(B) HKTB,
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fofc func(C) HKTC,
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chainab func(HKTA, func(A) HKTB) HKTB,
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chainac func(HKTA, func(A) HKTC) HKTC,
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chainbc func(HKTB, func(B) HKTC) HKTC,
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ab func(A) B,
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bc func(B) C,
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) func(fa HKTA) bool {
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return func(fa HKTA) bool {
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afb := F.Flow2(ab, fofb)
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bfc := F.Flow2(bc, fofc)
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left := chainbc(chainab(fa, afb), bfc)
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right := chainac(fa, func(a A) HKTC {
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return chainbc(afb(a), bfc)
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})
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return assert.True(t, eq.Equals(left, right), "Chain associativity")
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}
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}
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// AssertLaws asserts the apply laws `identity`, `composition`, `associative composition` and `associativity`
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func AssertLaws[HKTA, HKTB, HKTC, HKTAB, HKTBC, HKTAC, HKTABAC, A, B, C any](t *testing.T,
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eqa E.Eq[HKTA],
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eqc E.Eq[HKTC],
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fofa func(A) HKTA,
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fofb func(B) HKTB,
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fofc func(C) HKTC,
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fofab func(func(A) B) HKTAB,
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fofbc func(func(B) C) HKTBC,
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faa func(HKTA, func(A) A) HKTA,
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fab func(HKTA, func(A) B) HKTB,
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fac func(HKTA, func(A) C) HKTC,
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fbc func(HKTB, func(B) C) HKTC,
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fmap func(HKTBC, func(func(B) C) func(func(A) B) func(A) C) HKTABAC,
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chainab func(HKTA, func(A) HKTB) HKTB,
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chainac func(HKTA, func(A) HKTC) HKTC,
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chainbc func(HKTB, func(B) HKTC) HKTC,
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fapab func(HKTAB, HKTA) HKTB,
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fapbc func(HKTBC, HKTB) HKTC,
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fapac func(HKTAC, HKTA) HKTC,
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fapabac func(HKTABAC, HKTAB) HKTAC,
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ab func(A) B,
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bc func(B) C,
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) func(fa HKTA) bool {
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// apply laws
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apply := L.AssertLaws(t, eqa, eqc, fofab, fofbc, faa, fab, fac, fbc, fmap, fapab, fapbc, fapac, fapabac, ab, bc)
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// chain laws
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associativity := AssertAssociativity(t, eqc, fofa, fofb, fofc, chainab, chainac, chainbc, ab, bc)
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return func(fa HKTA) bool {
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return apply(fa) && associativity(fa)
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}
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}
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