Add Produce The Zero Value Of A Generic Type as a Go TIL

go/produce-the-zero-value-of-a-generic-type.md

@@ -0,0 +1,32 @@
+# Produce The Zero Value For A Generic Type
+
+While writing a _pop_ function that would work with slices of a generic type, I
+ran into the issue of needing to produce a zero value of type `T` when
+returning early for an empty slice.
+
+The way to arbitrarily get the zero value of a generic in Go is with `*new(T)`.
+
+I was able to use this in my `Pop` function like so:
+
+```go
+func Pop[T any](slice []T) (T, error) {
+	if len(slice) == 0 {
+		return *new(T), fmt.Errorf("cannot pop an empty slice")
+	}
+
+	lastItem := slice[len(slice)-1]
+
+	slice = slice[:len(slice)-1]
+
+	return lastItem, nil
+}
+```
+
+If this is happening in multiple functions and we want a more self-documenting
+approach, we can pull it out into a function `zero`:
+
+```go
+func zero[T any]() T {
+	return *new(T)
+}
+```