Style definitions for nice terminal layouts 👄
package list
import (
"fmt"
"strings"
)
// Enumerator enumerates a list. Given a list of items and the index of the
// current enumeration, it returns the prefix that should be displayed for the
// current item.
//
// For example, a simple Arabic numeral enumeration would be:
// func Arabic(_ Items, i int) string {
// return fmt.Sprintf("%d.", i+1)
// }
// There are several predefined enumerators:
// - Alphabet
// - Arabic
// - Bullet
// - Dash
// - Roman
// Or, define your own.
type Enumerator func(items Items, index int) string
// Indenter indents the children of a tree.
// Indenters allow for displaying nested tree items with connecting borders
// to sibling nodes.
// For example, the default indenter would be:
// func TreeIndenter(children Children, index int) string {
// if children.Length()-1 == index {
// return "│ "
// return " "
type Indenter func(items Items, index int) string
// Alphabet is the enumeration for alphabetical listing.
// Example:
// a. Foo
// b. Bar
// c. Baz
// d. Qux.
func Alphabet(_ Items, i int) string {
if i >= abcLen*abcLen+abcLen {
return fmt.Sprintf("%c%c%c.", 'A'+i/abcLen/abcLen-1, 'A'+(i/abcLen)%abcLen-1, 'A'+i%abcLen)
}
if i >= abcLen {
return fmt.Sprintf("%c%c.", 'A'+i/abcLen-1, 'A'+(i)%abcLen)
return fmt.Sprintf("%c.", 'A'+i%abcLen)
const abcLen = 26
// Arabic is the enumeration for arabic numerals listing.
// 1. Foo
// 2. Bar
// 3. Baz
// 4. Qux.
func Arabic(_ Items, i int) string {
return fmt.Sprintf("%d.", i+1)
// Roman is the enumeration for roman numerals listing.
// I. Foo
// II. Bar
// III. Baz
// IV. Qux.
func Roman(_ Items, i int) string {
var (
roman = []string{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"}
arabic = []int{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}
result strings.Builder
for v, value := range arabic {
for i >= value-1 {
i -= value
result.WriteString(roman[v])
result.WriteRune('.')
return result.String()
// Bullet is the enumeration for bullet listing.
// • Foo
// • Bar
// • Baz
// • Qux.
func Bullet(Items, int) string {
return "•"
// Asterisk is an enumeration using asterisks.
// * Foo
// * Bar
// * Baz
// * Qux.
func Asterisk(Items, int) string {
return "*"
// Dash is an enumeration using dashes.
// - Foo
// - Bar
// - Baz
// - Qux.
func Dash(Items, int) string {
return "-"
