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fix: implement FoldMap

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Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>
This commit is contained in:
Dr. Carsten Leue
2023-08-10 18:08:11 +02:00
parent 39c6108bf5
commit 1b1dccc551
11 changed files with 306 additions and 1 deletions
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17
array/generic/array.go
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@@ -18,6 +18,7 @@ package generic
import (
F "github.com/IBM/fp-go/function"
"github.com/IBM/fp-go/internal/array"
M "github.com/IBM/fp-go/monoid"
O "github.com/IBM/fp-go/option"
"github.com/IBM/fp-go/tuple"
)
@@ -209,3 +210,19 @@ func Copy[AS ~[]A, A any](b AS) AS {
copy(buf, b)
return buf
}
func FoldMap[AS ~[]A, A, B any](m M.Monoid[B]) func(func(A) B) func(AS) B {
return func(f func(A) B) func(AS) B {
return func(as AS) B {
return array.Reduce(as, func(cur B, a A) B {
return m.Concat(cur, f(a))
}, m.Empty())
}
}
}
func Fold[AS ~[]A, A any](m M.Monoid[A]) func(AS) A {
return func(as AS) A {
return array.Reduce(as, m.Concat, m.Empty())
}
}

8
array/generic/sort.go
View File

@@ -18,11 +18,17 @@ package generic
import (
"sort"
F "github.com/IBM/fp-go/function"
O "github.com/IBM/fp-go/ord"
)
// Sort implements a stable sort on the array given the provided ordering
func Sort[GA ~[]T, T any](ord O.Ord[T]) func(ma GA) GA {
return SortByKey[GA](ord, F.Identity[T])
}
// SortByKey implements a stable sort on the array given the provided ordering on an extracted key
func SortByKey[GA ~[]T, K, T any](ord O.Ord[K], f func(T) K) func(ma GA) GA {
return func(ma GA) GA {
// nothing to sort
@@ -34,7 +40,7 @@ func Sort[GA ~[]T, T any](ord O.Ord[T]) func(ma GA) GA {
cpy := make(GA, l)
copy(cpy, ma)
sort.Slice(cpy, func(i, j int) bool {
return ord.Compare(cpy[i], cpy[j]) < 0
return ord.Compare(f(cpy[i]), f(cpy[j])) < 0
})
return cpy
}