cursed: add reduce

Signed-off-by: Xe Iaso <me@xeiaso.net>

1 files changed, 53 insertions, 0 deletions

diff --git a/cursed/reduce.go b/cursed/reduce.go
new file mode 100644
index 0000000..bd9f865
--- /dev/null
+++ b/cursed/reduce.go
@@ -0,0 +1,53 @@
+package cursed
+
+import "golang.org/x/exp/constraints"
+
+func Reduce[D any](data []D, doer func(D, D) D) D {
+	var initial D
+
+	return Fold[D, D](initial, data, doer)
+}
+
+func Fold[T any, U any](initial U, data []T, doer func(T, U) U) U {
+	acc := initial
+	for _, d := range data {
+		temp := doer(d, acc)
+		acc = temp
+	}
+
+	return acc
+}
+
+type Number interface {
+	constraints.Float | constraints.Integer
+}
+
+func Sum[T Number](data []T) T {
+	return Reduce[T](data, func(x, y T) T {
+		return x + y
+	})
+}
+
+func Max[T Number](data []T) T {
+	return Reduce[T](data, func(x, y T) T {
+		if x > y {
+			return x
+		} else if y < x {
+			return y
+		} else {
+			return x // x == y
+		}
+	})
+}
+
+func Min[T Number](data []T) T {
+	return Reduce[T](data, func(x, y T) T {
+		if x > y {
+			return y
+		} else if y < x {
+			return x
+		} else {
+			return x // x == y
+		}
+	})
+}