Indentation

Indentation is how far in a line starts. It shows which lines belong inside which, the way a list inside a list is pushed further in. These rules decide the empty space in a file, and turf fmt already applies four of them for you.

By the end of this page you will

Indent Turf code the way everyone else does.
Use blank lines to split code into steps.
Know which of these rules turf fmt fixes today.

Spaces and empty lines are invisible to the compiler and very visible to people. A tool can fix all of them, so they are the easiest rules to follow: run turf fmt --write and they are done.

TSG-101 Indent with four spaces

RequiredChecked by turf fmt

Each level of nesting is four spaces deeper than the one around it. Never use tabs: a tab looks two spaces wide on one screen and eight on another, so the same file looks different for everyone.

tsg_101.tr

fn main(): int {    for i in 0..3 {        if i == 1 {            printline(i);        }    }    return 0;}

Don't

tsg_101_avoid.tr

fn main(): int {  for i in 0..3 {          if i == 1 {     printline(i);          }  }  return 0;}

TSG-102 No spaces at the end of a line

RequiredChecked by turf fmt

Spaces after the last character of a line are invisible, so nobody adds them on purpose. They only show up as noise when someone else’s editor removes them and every line looks changed.

TSG-103 Never more than one blank line in a row

RequiredChecked by turf fmt

A blank line is a paragraph break: it separates one idea from the next. Put one blank line between top-level declarations, and use single blank lines inside a function to split it into steps. Two or more in a row say nothing a single one does not.

tsg_103.tr

fn twice(n: int): int {    return n * 2;}fn main(): int {    immut n: int = 4;    printline(twice(n));    return 0;}

Don't

tsg_103_avoid.tr

fn twice(n: int): int {    return n * 2;}fn main(): int {    immut n: int = 4;    printline(twice(n));    return 0;}

TSG-104 End every file with one newline

RequiredChecked by turf fmt

The last line of a file ends with a newline character, and there is exactly one. Many tools expect it, and without it the last line shows up as changed every time someone adds a line after it.

TSG-105 Keep lines to 100 characters

RecommendedNo tool checks this yet

A line of code fits in 100 characters, counting the indentation. Long lines push the end of a thought off the side of the screen, and side-by-side views in code review cut them off. When a call or a signature gets too long, break it after a comma and indent the continuation by one level.

tsg_105.tr

fn describe(name: string, age: int, city: string, job: string): string {    return name + " is " + (age to string) + ", lives in " + city        + " and works as " + job;}fn main(): int {    printline(describe("Mira", 34, "Lisbon", "a carpenter"));    return 0;}

Don't

tsg_105_avoid.tr

fn describe(name: string, age: int, city: string, job: string): string {    return name + " is " + (age to string) + ", lives in " + city + " and works as " + job + "." + "";}fn main(): int {    printline(describe("Mira", 34, "Lisbon", "a carpenter"));    return 0;}