Merge pull request #122 from bits-and-blooms/dlemire/doc_read_from

preparing a new release

.github/workflows/test.yml

@@ -1,5 +1,6 @@
-on: pull_request
 name: Test
+
+on: [push, pull_request]
 permissions:
   contents: read
 jobs:

README.md

@@ -69,13 +69,48 @@ func main() {
 }
 ```
 
-As an alternative to BitSets, one should check out the 'big' package, which provides a (less set-theoretical) view of bitsets.
 
 Package documentation is at: https://pkg.go.dev/github.com/bits-and-blooms/bitset?tab=doc
 
+## Serialization
+
+
+You may serialize a bitset safely and portably to a stream
+of bytes as follows:
+```Go
+    const length = 9585
+	const oneEvery = 97
+	bs := bitset.New(length)
+	// Add some bits
+	for i := uint(0); i < length; i += oneEvery {
+		bs = bs.Set(i)
+	}
+
+	var buf bytes.Buffer
+	n, err := bs.WriteTo(&buf)
+	if err != nil {
+		// failure
+	}
+	// Here n == buf.Len()
+```
+You can later deserialize the result as follows:
+
+```Go
+	// Read back from buf
+	bs = bitset.New()
+	n, err = bs.ReadFrom(&buf)
+	if err != nil {
+		// error
+	}
+	// n is the number of bytes read
+```
+
+The `ReadFrom` function attempts to read the data into the existing
+BitSet instance, to minimize memory allocations.
+
 ## Memory Usage
 
-The memory usage of a bitset using N bits is at least N/8 bytes. The number of bits in a bitset is at least as large as one plus the greatest bit index you have accessed. Thus it is possible to run out of memory while using a bitset. If you have lots of bits, you might prefer compressed bitsets, like the [Roaring bitmaps](http://roaringbitmap.org) and its [Go implementation](https://github.com/RoaringBitmap/roaring).
+The memory usage of a bitset using `N` bits is at least `N/8` bytes. The number of bits in a bitset is at least as large as one plus the greatest bit index you have accessed. Thus it is possible to run out of memory while using a bitset. If you have lots of bits, you might prefer compressed bitsets, like the [Roaring bitmaps](http://roaringbitmap.org) and its [Go implementation](https://github.com/RoaringBitmap/roaring).
 
 ## Implementation Note