lean into examples

examples/maps/maps.go

@@ -0,0 +1,43 @@
+// Maps are Go's built-in associative data type (sometimes
+// called "hashes" or "dicts" in other languages).
+
+package main
+
+import "fmt"
+
+func main() {
+    // To create an empty map, use the builtin `make`:
+    // `make(map[key-type]val-type)`.
+    m := make(map[string]int)
+
+    // Set key/value pairs using typical `name[key] = val`
+    // syntax.
+    m["k1"] = 7
+    m["k2"] = 13
+
+    // Printing a map with e.g. `Println` will show all of
+    // its key/value pairs, which can be useful for
+    // debugging.
+    fmt.Println("map:", m)
+
+    // Get a value for a key with `name[key]`.
+    v1 := m["k1"]
+    fmt.Println("v1: ", v1)
+
+    // The builtin `len` function returns the number of
+    // key/value pairs when called on a map.
+    fmt.Println("len:", len(m))
+
+    // The builtin `delete` removes key/value pairs from
+    // a map
+    delete(m, "k2")
+    fmt.Println("map:", m)
+
+    // The optional second return value when getting a
+    // value from a map indiciates if the key was present
+    // in the map. This can be used to disambiguate
+    // between missing keys and keys with zero values
+    // like `0` or `""`.
+    _, prs := m["k2"]
+    fmt.Println("prs:", prs)
+}

examples/maps/maps.sh

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+$ go run maps.go 
+map: map[k1:7 k2:13]
+v1:  7
+len: 2
+map: map[k1:7]
+prs: false