(* ======================== *)
(* Core Character Sequences *)
(* ======================== *)
white_space ::= '\u0020' | '\u0009' | '\u000D' | '\u000A'
lparen ::= '(';
rparen ::= ')';
paren ::= lparen | rparen;
lbracket ::= '[';
rbracket ::= ']';
bracket ::= lbracket | rbracket;
lbrace ::= '{';
rbrace ::= '}';
brace ::= lbrace | rbrace;
digit ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9';
hex ::= '0' | ... | '9' | 'A' | ... | 'F' | 'a' | ... | 'f' ;
upper ::= 'A' | ... | 'Z' | Lu | Lt | Nl
| Lo upper only
| Lm upper only;
lower ::= 'a' | ... | 'z' | Ll
| Lo lower only
| Lm lower only;
letter ::= upper | lower;
escape_unicode ::= '\', 'u', hex, hex, hex, hex;
escape_char ::= '\', ('b' | 'f' | 'n' | 'r' | 't' | '\' | '"' | "'");
escape_seq ::= escape_unicode | escape_char;
number_integer ::= '0' | digit, [{digit}];
number_float ::= number_integer, '.', number_integer;
newline ::= '\n';
printable_char ::= printable utf8;
char_char ::= printable_char without newline or single quote
| escape_seq;
string_char ::= printable_char without newline or double quote
| escape_seq;
(* Comments *)
comment ::= '-', '-', {utf8};
docstring ::= '-', '-', '-', {utf8};
(* ======== *)
(* Keywords *)
(* ======== *)
k_type ::= 't', 'y', 'p', 'e';
k_class ::= 'c', 'l', 'a', 's', 's';
k_alias ::= 'a', 'l', 'i', 'a', 's';
k_const ::= 'c', 'o', 'n', 's', 't';
k_enum ::= 'e', 'n', 'u', 'm';
k_record ::= 'r', 'e', 'c', 'o', 'r', 'd';
k_object ::= 'o', 'b', 'j', 'e', 'c', 't';
k_let ::= 'l', 'e', 't';
k_mut ::= 'm', 'u', 't';
k_export ::= 'e', 'x', 'p', 'o', 'r', 't';
(* Starts an import definition. *)
k_import ::= 'i', 'm', 'p', 'o', 'r', 't';
(* Denotes a namespace declaration. *)
k_namespace ::= 'n', 'a', 'm', 'e', 's', 'p', 'a', 'c', 'e';
(* Starts an infix function definition *)
k_infix ::= 'i', 'n', 'f', 'i', 'x';
(* Starts a function definition. *)
k_fn ::= 'f', 'n';
(* Ends any block definition. Must be followed by the keyword of the block. *)
k_end ::= 'e', 'n', 'd';
(* Initiates a pattern match against some value. *)
k_match ::= 'm', 'a', 't', 'c', 'h';
(* Initiates a pattern matching case. Applicable to functions and matches. *)
k_case ::= 'c', 'a', 's', 'e';
k_lambda ::= 'λ';
(* Used in if/else syntax. Starts such a block and used in 'else if'. *)
k_if ::= 'i', 'f';
(* Used in if/else syntax. Must follow the condition of any 'if'. *)
k_then ::= 't', 'h', 'e', 'n';
(* Used in if/else syntax. Indicates an 'else if' or 'else'. *)
k_else ::= 'e', 'l', 's', 'e';
(* Used in do/return syntax. Indicates the start of such a structure. *)
k_do ::= 'd', 'o';
(* Used in do/return syntax. Indicates the final output value. *)
k_return ::= 'r', 'e', 't', 'u', 'r', 'n';
(* Indicates a type constructor. *)
k_given ::= 'g', 'i', 'v', 'e', 'n';
(* Function modifier which restricts use to the enclosing scope. *)
k_private ::= 'p', 'r', 'i', 'v', 'a', 't', 'e';
(* true is a Boolean literal *)
k_true ::= 't', 'r', 'u', 'e';
(* false is a Boolean literal *)
k_false ::= 'f', 'a', 'l', 's', 'e';
(* defn is fn but for definitions without implementations *)
k_false ::= 'd', 'e', 'f', 'n';
keyword ::= k_type | k_class | k_alias | k_const | k_enum | k_record
| k_object | k_let | k_mut | k_export | k_import
| k_namespace | k_infix | k_fn | k_end | k_match | k_case
| k_lambda | k_if | k_then | k_else | k_do | k_return
| k_given | k_private | k_true | k_false | k_defn;
(* ============== *)
(* Literal Values *)
(* ============== *)
literal_bool ::= k_true | k_false;
literal_integer ::= ['-'], number_integer;
literal_float ::= ['-'], number_float;
literal_char ::= "'", char_char, "'";
literal_string ::= '"', {string_char}, "'";
empty_tuple ::= op_tuple, lparen, rparen;
empty_list ::= lbracket, rbracket;
literal ::= literal_bool
| literal_integer
| literal_float
| literal_char
| literal_string
| empty_tuple
| empty_list;
(* ========= *)
(* Operators *)
(* ========= *)
(* Type hole used for development -- will resolve/compile, but fail at
runtime. *)
hole ::= '?', '?', '?';
(* Used for splat imports: import foo.bar.baz.* is an example. *)
op_import_splat ::= '*';
(* Used to access members. Relevant for namespaces, records, enums, classes. *)
op_member ::= '.';
(* Standard separator for type definitions, tuples and records. *)
op_comma ::= ',';
(* A | B is a type which can be either A or B. *)
op_type_union ::= '|';
(* List operator. Prepend LHS to RHS. Can be used in pattern matching. *)
op_list_prepend ::= ':', '-';
(* Only valid adjacent to a name declaration. Explicitly declare the type that
the name has. *)
op_bind_type ::= ':';
(* Bind the RHS expression to the LHS name. *)
op_bind_value ::= ':', '=';
(* Used in function definitions: the LHS input produces RHS output. *)
op_fn_return ::= '-', '>';
(* Binds the result contained in the RHS expression to the name on the LHS. *)
(* Note that "contained" refers to the value in the [Bi]Monad. *)
op_bind_do ::= '<', '-';
(* Indicates some type is constrained by some type class, ex F * :: Functor *)
op_class_member ::= ':', ':';
(* Indicates the start of a pattern matching case, used in both forms:
case <pattern> => <expr>
λ <pattern> => <expr>
The λ form is preferred for functions, 'case' is preferred for 'match'. *)
op_case ::= '=', '>';
(* Declares a tuple, as in #(a, b, c) *)
op_tuple ::= '#';
operator ::= hole | op_import_splat | op_member | op_comma
| op_type_union | op_list_prepend | op_bind_type
| op_bind_value | op_fn_return | -> op_bind_do
| op_class_member | op_case | op_tuple;
(* ===== *)
(* Names *)
(* ===== *)
(* Used to denote an anonymous value, such as ignoring a pattern part. *)
name_anon_value ::= '_';
(* Used to denote an anonymous parameter in a type definition. Helps to describe
some type with a particular shape without naming each part. *)
name_anon_type ::= '*';