rework

README.md

@@ -10,13 +10,13 @@ package main
 import (
 	"fmt"
 
-	"github.com/annybs/go/random"
+	"code.aneur.in/go/random"
 )
 
 func main() {
 	n := make([]bool, 10)
 	for i := range n {
-		fmt.Println(random.Str(4 + i))
+		fmt.Println(random.Alpha(4 + i))
 	}
 }
 ```

random.go

@@ -1,9 +1,56 @@
 package random
 
-import "math/rand"
+import (
+	"math/rand"
+	"strings"
+)
 
-// Str generates a random string of the specified length using an alphanumeric character set.
-var Str = String([]rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"))
+// Standard character set.
+const (
+	CharsetAlpha        string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	CharsetAlphanumeric string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	CharsetAlphaLower   string = "abcdefghijklmnopqrstuvwxyz"
+	CharsetAlphaUpper   string = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	CharsetNumeric      string = "0123456789"
+	CharsetSymbols      string = "!@#$%^&*()-=_+[]{};:,.<>/?"
+)
+
+// Alpha generates a random string of the specified length using a mixed-case alphabetical character set.
+var Alpha = String([]rune(CharsetAlpha))
+
+// Alphanumeric generates a random string of the specified length using an alphanumeric character set.
+var Alphanumeric = String([]rune(CharsetAlphanumeric))
+
+// AlphaLower generates a random string of the specified length using a lowercase alphabetical character set.
+var AlphaLower = String([]rune(CharsetAlphaLower))
+
+// AlphaUpper generates a random string of the specified length using an uppercase alphabetical character set.
+var AlphaUpper = String([]rune(CharsetAlphaUpper))
+
+// Numeric generates a random string of the specified length containing numbers only.
+var Numeric = String([]rune(CharsetNumeric))
+
+// Password generates a random string of the specified length, including the specified counts of numbers and symbols.
+func Password(length, numbers, symbols int) string {
+	parts := []string{
+		Alpha(length - numbers - symbols),
+		Numeric(numbers),
+		Symbols(symbols),
+	}
+
+	str := strings.Join(parts, "")
+	m := map[int]rune{}
+	for i, c := range str {
+		m[i] = c
+	}
+
+	jumbled := []rune{}
+	for _, c := range m {
+		jumbled = append(jumbled, c)
+	}
+
+	return string(jumbled)
+}
 
 // String returns a function that can be used to generate a random string of the specified length using the given character set.
 func String(chars []rune) func(length int) string {
@@ -16,3 +63,6 @@ func String(chars []rune) func(length int) string {
 		return string(s)
 	}
 }
+
+// Symbols generates a random string of the specified length using a limited selection of symbols.
+var Symbols = String([]rune(CharsetSymbols))