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Document tuple syntax

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Closes #13837
This commit is contained in:
Evin Yulo 2022-12-10 03:10:55 +00:00 committed by Veikka Tuominen
parent a44085dc2a
commit fc07e1a267
1 changed files with 24 additions and 40 deletions
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doc/langref.html.in
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@ -2433,43 +2433,6 @@ test "array initialization with function calls" {
{#code_end#}
{#see_also|for|Slices#}
{#header_open|Anonymous List Literals#}
<p>Similar to {#link|Enum Literals#} and {#link|Anonymous Struct Literals#}
the type can be omitted from array literals:</p>
{#code_begin|test|anon_list#}
const std = @import("std");
const expect = std.testing.expect;
test "anonymous list literal syntax" {
var array: [4]u8 = .{11, 22, 33, 44};
try expect(array[0] == 11);
try expect(array[1] == 22);
try expect(array[2] == 33);
try expect(array[3] == 44);
}
{#code_end#}
<p>
If there is no type in the {#link|result location|Result Location Semantics#} then an
anonymous list literal actually turns into a {#link|struct#} with numbered field names:
</p>
{#code_begin|test|infer_list_literal#}
const std = @import("std");
const expect = std.testing.expect;
test "fully anonymous list literal" {
try dump(.{ @as(u32, 1234), @as(f64, 12.34), true, "hi"});
}
fn dump(args: anytype) !void {
try expect(args.@"0" == 1234);
try expect(args.@"1" == 12.34);
try expect(args.@"2");
try expect(args.@"3"[0] == 'h');
try expect(args.@"3"[1] == 'i');
}
{#code_end#}
{#header_close#}
{#header_open|Multidimensional Arrays#}
<p>
Multidimensional arrays can be created by nesting arrays:
@ -3578,15 +3541,21 @@ fn dump(args: anytype) !void {
try expect(args.s[1] == 'i');
}
{#code_end#}
{#header_close#}
{#header_open|Tuples#}
<p>
Anonymous structs can be created without specifying field names, and are referred to as "tuples".
</p>
<p>
The fields are implicitly named using numbers starting from 0. Because their names are integers,
the {#syntax#}@"0"{#endsyntax#} syntax must be used to access them. Names inside {#syntax#}@""{#endsyntax#} are always recognised as {#link|identifiers|Identifiers#}.
they cannot be accessed with {#syntax#}.{#endsyntax#} syntax without also wrapping them in
{#syntax#}@""{#endsyntax#}. Names inside {#syntax#}@""{#endsyntax#} are always recognised as
{#link|identifiers|Identifiers#}.
</p>
<p>
Like arrays, tuples have a .len field, can be indexed and work with the ++ and ** operators. They can also be iterated over with {#link|inline for#}.
Like arrays, tuples have a .len field, can be indexed (provided the index is comptime-known)
and work with the ++ and ** operators. They can also be iterated over with {#link|inline for#}.
</p>
{#code_begin|test|tuple#}
const std = @import("std");
@ -6488,7 +6457,22 @@ test "coercion between unions and enums" {
{#see_also|union|enum#}
{#header_close#}
{#header_open|Type Coercion: undefined#}
<p>{#link|undefined#} can be cast to any type.</p>
<p>{#link|undefined#} can be coerced to any type.</p>
{#header_close#}
{#header_open|Type Coercion: tuples to arrays#}
<p>{#link|Tuples#} can be coerced to arrays, if all of the fields have the same type.</p>
{#code_begin|test|test_coerce_tuples_arrays#}
const std = @import("std");
const expect = std.testing.expect;
const Tuple = struct{ u8, u8 };
test "coercion from homogenous tuple to array" {
const tuple: Tuple = .{5, 6};
const array: [2]u8 = tuple;
_ = array;
}
{#code_end#}
{#header_close#}
{#header_close#}