Lexical

Strings and Characters

String literals may be defined using q{...} or "...", when using the latter syntax d or w may be prepended to dictate the size of the characters (dchar or wchar) or r to dictate that all escapes are ignored.

Character literals may be defined using '...' in which a single character is defined.

Escapes

Escape sequences are sequences of characters which result in a special character being used.

Sequence	Definition
\'	'
\"	"
\\	\
\0	Null terminator.
\a	Alert.
\b	Backspace.
\f	Form backfeed.
\n	Newline.
\r	Carriage return.
\t	Horizontal tab.
\v	Vertical tab.
\xhh..	Hexadecimal character insert.

Literals

Literal suffixes are suffixes which may be appended to a literal to change the way that the literal is formatted or interpreted.

Integral -Fix	Definition
u	Unsigned, suffix.
U	Signed, suffix.
L	64-bit integer, suffix.
f	32-bit floating point, suffix.
0x	Hexadecimal, prefix.
0X	Hexadecimal, prefix.
0o	Octal, prefix.
0b	Binary, prefix.

All integer literals may have their values separated by underscores for clarity, in replacement of commas such as in 10_000 where the literal is the value 10 thousand.

Comments, Terminators, and Scopes

// comment

/* multi-line comment */

Comments in Fern use the syntax \\ for single-line and /*..*/ for multi-line.

[type] name;

[type] name[(parameters)]

Terminators in Fern are ;, which are necessary to end any expression or declaration of a signature (such as a type or function.)

{ .. }

Scopes in Fern are started and ended using curly brackets.

Keywords

Keyword	Definition
this	Refers to the parent instance of the scope in which it was used, it is a comptime error if the scope has no instance.
return	Return
delete	Destruct
bool	Builtin
true	Builtin
false	Builtin
byte	Builtin
ubyte	Builtin
short	Builtin
ushort	Builtin
int	Builtin
uint	Builtin
long	Builtin
float	Builtin
double	Builtin
ulong	Builtin
nint	Builtin
nuint	Builtin
void	Builtin
char	Builtin
wchar	Builtin
dchar	Builtin
string	Builtin
wstring	Builtin
dstring	Builtin
pure	Attribute
const	Attribute
static	Attribute
public	Attribute
private	Attribute
internal	Attribute
partial	Attribute
system	Attribute
trusted	Attribute
safe	Attribute
inline	Attribute
mustuse	Attribute
ref	Attribute
align	Attribute
offset	Attribute
atomic	Attribute
alias	Alias
module	Type
import	Type
struct	Type
class	Type
tagged	Type
unittest	Unittest
function	Function Pointer
delegate	Function Pointer
if	Statement
else	Statement
foreach	Statement
foreach_reverse	Statement
while	Statement
goto	Statement
with	Statement
break	Statement
continue	Statement
mixin	Mixin
is	Conditional
debug	Versioning
export	Reserved
extern	Reserved
assert	Reserved
__asm	Reserved

Special Symbols

The prefix __ is resserved for implementation and thus should be blacklisted for use in declarations. Such implementation are as follows, but implementations may add to this:

Symbol	Definition
__Windows	Is Windows being targeted?
__Linux	Is Linux being targeted?
__OSX	Is OSX being targeted?
__Posix	Is Posix being targeted?
__iOS	Is iOS being targeted?
__tvOS	Is tvOS being targeted?
__watchOS	Is watchOS being targeted?
__visionOS	Is visionOS being targeted?
__FreeBSD	Is FreeBSD being targeted?
__OpenBSD	Is OpenBSD being targeted?
__NetBSD	Is NetBSD being targeted?
__Solaris	Is Solaris being targeted?
__Android	Is Android being targeted?
__x86	Is x86 being targeted?
__x86_64	Is x86_64 being targeted?
__x64	Is 64-bit being targeted?
__x32	Is 32-bit being targeted?
__fnc	Is the Fern Native Compiler being used?
.sizeof	The size in bytes of the symbol being targeted, this is a member.
.alignof	The alignment in bytes of the symbol being targeted, this is a member.
.offsetof	The offset in bytes of the symbol being targeted, this is a member.
.typeof	The type of the symbol being targeted, this is a member.
.tag	The tag of a tagged, this is a member.
.ptr	The pointer of an object, this is a member.
.length	The length of an array, this is a member.