Hash doc (ardanlabs#317)

* hash doc

* wikipedia link

* package last

* linters

* removed nolint

Author: tebeka

topics/go/algorithms/data/hash/doc.go

@@ -0,0 +1,32 @@
+/*
+Package hash implements a hash table.
+
+Hash table
+
+        hashKey(key) ────────┐
+                             │
+                             ↓
+    ┌────┬─────┬─────┬────┬─────┬─────┬─────┬─────┐
+    │    │     │     │    │     │     │     │     │  ←── bucket
+    └────┴─────┴─────┴────┴─────┴─────┴─────┴─────┘
+             │               │
+             ↓               ↓
+       ┌─────────────┐  ┌─────────────┐
+       │ key │ value │  │ key │ value │  ←── entry
+       ├─────────────┤  ├─────────────┤
+       │ key │ value │  │ key │ value │
+       ├─────────────┤  └─────────────┘
+       │ key │ value │
+       ├─────────────┤
+       │ key │ value │
+       ├─────────────┤
+       │ key │ value │
+       └─────────────┘
+
+
+- hashKey(key) returns a number between 0 to len(buckets)-1
+- We use a slice of entries as a bucket to handles cases where two or more keys
+  are hashed to the same bucket
+- See more at https://en.wikipedia.org/wiki/Hash_table
+*/
+package hash

topics/go/algorithms/data/hash/hash.go

@@ -133,6 +133,7 @@ func (h *Hash) hashKey(key string) int {
 	h.hash.Reset()
 
 	// Write the key to the maphash to update the current state.
+	// We don't check error value since WriteString never fails.
 	h.hash.WriteString(key)
 
 	// Ask the maphash for its current state which we will