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2bd9911804
In the year of our lord 2024 we should not be writing for loops for standard operations. Here we introduce named slice operations not found in the golang slices package. Note all these functions are pure.
138 lines
2.7 KiB
Go
138 lines
2.7 KiB
Go
package fn
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import (
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"slices"
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"testing"
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"github.com/stretchr/testify/require"
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)
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func even(a int) bool { return a%2 == 0 }
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func odd(a int) bool { return a%2 != 0 }
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func TestAll(t *testing.T) {
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x := []int{0, 2, 4, 6, 8}
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require.True(t, All(even, x))
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require.False(t, All(odd, x))
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y := []int{1, 3, 5, 7, 9}
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require.False(t, All(even, y))
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require.True(t, All(odd, y))
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z := []int{0, 2, 4, 6, 9}
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require.False(t, All(even, z))
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require.False(t, All(odd, z))
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}
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func TestAny(t *testing.T) {
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x := []int{1, 3, 5, 7, 9}
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require.False(t, Any(even, x))
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require.True(t, Any(odd, x))
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y := []int{0, 3, 5, 7, 9}
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require.True(t, Any(even, y))
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require.True(t, Any(odd, y))
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z := []int{0, 2, 4, 6, 8}
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require.True(t, Any(even, z))
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require.False(t, Any(odd, z))
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}
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func TestMap(t *testing.T) {
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inc := func(i int) int { return i + 1 }
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x := []int{0, 2, 4, 6, 8}
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y := Map(inc, x)
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z := []int{1, 3, 5, 7, 9}
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require.True(t, slices.Equal(y, z))
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}
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func TestFilter(t *testing.T) {
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x := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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y := Filter(even, x)
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require.True(t, All(even, y))
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z := Filter(odd, y)
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require.Zero(t, len(z))
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}
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func TestFoldl(t *testing.T) {
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seed := []int{}
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stupid := func(s []int, a int) []int { return append(s, a) }
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x := []int{0, 1, 2, 3, 4}
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r := Foldl(stupid, seed, x)
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require.True(t, slices.Equal(x, r))
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}
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func TestFoldr(t *testing.T) {
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seed := []int{}
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stupid := func(a int, s []int) []int { return append(s, a) }
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x := []int{0, 1, 2, 3, 4}
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z := Foldr(stupid, seed, x)
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slices.Reverse[[]int](x)
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require.True(t, slices.Equal(x, z))
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}
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func TestFind(t *testing.T) {
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x := []int{10, 11, 12, 13, 14, 15}
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div3 := func(a int) bool { return a%3 == 0 }
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div8 := func(a int) bool { return a%8 == 0 }
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require.Equal(t, Find(div3, x), Some(12))
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require.Equal(t, Find(div8, x), None[int]())
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}
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func TestFlatten(t *testing.T) {
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x := [][]int{{0}, {1}, {2}}
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y := Flatten(x)
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require.True(t, slices.Equal(y, []int{0, 1, 2}))
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}
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func TestReplicate(t *testing.T) {
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require.True(t, slices.Equal([]int{1, 1, 1, 1, 1}, Replicate(5, 1)))
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}
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func TestSpan(t *testing.T) {
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x := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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lt5 := func(a int) bool { return a < 5 }
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low, high := Span(lt5, x)
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require.True(t, slices.Equal(low, []int{0, 1, 2, 3, 4}))
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require.True(t, slices.Equal(high, []int{5, 6, 7, 8, 9}))
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}
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func TestSplitAt(t *testing.T) {
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x := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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fst, snd := SplitAt(5, x)
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require.True(t, slices.Equal(fst, []int{0, 1, 2, 3, 4}))
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require.True(t, slices.Equal(snd, []int{5, 6, 7, 8, 9}))
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}
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func TestZipWith(t *testing.T) {
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eq := func(a, b int) bool { return a == b }
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x := []int{0, 1, 2, 3, 4}
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y := Replicate(5, 1)
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z := ZipWith(eq, x, y)
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require.True(t, slices.Equal(
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z, []bool{false, true, false, false, false},
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))
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}
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