From afb344a1b1bad6068f492665e77b4796df15efd5 Mon Sep 17 00:00:00 2001
From: lucarin91 <lucarin@protonmail.com>
Date: Mon, 19 Jan 2026 16:00:15 +0100
Subject: [PATCH] feat: add iterator support

---
 go.mod  |  2 +-
 iter.go | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 iter.go

diff --git a/go.mod b/go.mod
index 37ff180..6ea1593 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module go.bug.st/f
 
-go 1.22.3
+go 1.25
 
 require github.com/stretchr/testify v1.9.0
 
diff --git a/iter.go b/iter.go
new file mode 100644
index 0000000..a94fb4b
--- /dev/null
+++ b/iter.go
@@ -0,0 +1,41 @@
+package f
+
+import "iter"
+
+// FilterIter takes an iterator and a matcher and returns only those elements that satisfy the matcher.
+func FilterIter[T any](values iter.Seq[T], matcher Matcher[T]) iter.Seq[T] {
+	return func(yield func(x T) bool) {
+		for x := range values {
+			if matcher(x) {
+				if !yield(x) {
+					return
+				}
+			}
+		}
+	}
+}
+
+// Map applies the Mapper function to each element of the iterator.
+func MapIter[T, U any](values iter.Seq[T], mapper Mapper[T, U]) iter.Seq[U] {
+	return func(yield func(x U) bool) {
+		for x := range values {
+			if !yield(mapper(x)) {
+				return
+			}
+		}
+	}
+}
+
+// Reducer is a function that reduces an iterator's elements to a single value.
+func ReduceIter[T any](values iter.Seq[T], reducer Reducer[T], initialValue ...T) T {
+	var result T
+	if len(initialValue) > 1 {
+		panic("initialValue must be a single value")
+	} else if len(initialValue) == 1 {
+		result = initialValue[0]
+	}
+	for v := range values {
+		result = reducer(result, v)
+	}
+	return result
+}