ws:ws    = " " | "\b" | "\f" | "\r" | "\t" | "\v";
wsc:ws   = comment;
nl:alias = "\n";

line-comment-content:nows  = [^\n]*;
line-comment:alias:nows    = "//" line-comment-content;
block-comment-content:nows = ([^*] | "*" [^/])*;
block-comment:alias:nows   = "/*" block-comment-content "*/";
comment-part:alias         = line-comment | block-comment;
comment:alias              = comment-part ("\n"? comment-part)*;

decimal-digit:alias = [0-9];
octal-digit:alias   = [0-7];
hexa-digit:alias    = [0-9a-fA-F];

decimal:alias:nows = [1-9] decimal-digit*;
octal:alias:nows   = "0" octal-digit*;
hexa:alias:nows    = "0" [xX] hexa-digit+;
int                = decimal | octal | hexa;

exponent:alias:nows = [eE] [+\-]? decimal-digit+;
float:nows          = decimal-digit+ "." decimal-digit* exponent?
                    | "." decimal-digit+ exponent?
                    | decimal-digit+ exponent;

string:nows = "\"" ([^\\"] | "\\" .)* "\"";

true       = "true";
false      = "false";
bool:alias = true | false;

symbol:nows = [a-zA-Z_][a-zA-Z_0-9]*;

spread-expression     = primary-expression "...";
list-sep:alias        = (nl | ",")+;
list-item:alias       = expression | spread-expression;
expression-list:alias = list-item (list-sep list-item)*;

list-fact:alias = "[" list-sep? expression-list? list-sep? "]";
list            = list-fact;
mutable-list    = "~" nl* list-fact;

expression-key     = "[" nl* expression nl* "]";
entry              = (symbol | string | expression-key) nl* ":" nl* expression;
entry-list:alias   = (entry | spread-expression) (list-sep (entry | spread-expression))*;
struct-fact:alias  = "{" list-sep? entry-list? list-sep? "}";
struct             = struct-fact;
mutable-struct     = "~" nl* struct-fact;

channel = "<>" | "<" nl* expression nl* ">";

parameter-list:alias = symbol (list-sep symbol)*;
collect-parameter    = "..." nl* symbol;
return               = "return" (nl* expression)?;
block                = "{" sep? statement-list? sep? "}";
function-fact:alias  = "(" list-sep?
                       parameter-list?
                       (list-sep collect-parameter)?
                       list-sep? ")" nl*
                       (simple-statement | block);
function             = "fn" nl* function-fact;
effect               = "fn" nl* "~" nl* function-fact;

range-from  = expression;
range-to    = expression;
range:alias = range-from? nl* ":" nl* range-to?;

simple-indexer:alias     = primary-expression "[" nl* expression nl* "]";
range-indexer:alias      = primary-expression "[" nl* range nl* "]";
expression-indexer       = simple-indexer | range-indexer;
symbol-indexer           = primary-expression nl* "." nl* symbol;

function-application = primary-expression "(" list-sep? expression-list? list-sep? ")";

expression-group:alias   = "(" nl* expression nl* ")";
primary-expression:alias = int
                         | float
                         | string
                         | bool
                         | symbol
                         | list
                         | mutable-list
                         | struct
                         | mutable-struct
                         | channel
                         | function
                         | effect
                         | expression-indexer
                         | symbol-indexer
                         | function-application
                         | receive
                         | expression-group;

binary-not = "^";
binary-and = "&";
binary-or  = "|";
xor        = "^";
and-not    = "&^";
lshift     = "<<";
rshift     = ">>";

plus  = "+";
minus = "-";
mul   = "*";
div   = "/";
mod   = "%";
add   = "+";
sub   = "-";

logical-not   = "!";
eq            = "==";
not-eq        = "!=";
less          = "<";
less-or-eq    = "<=";
greater       = ">";
greater-or-eq = ">=";
logical-and   = "&&";
logical-or    = "||";

chain:alias = "->";

unary-operator:alias = plus | minus | binary-not | logical-not;
unary-expression     = unary-operator primary-expression;

binary-op0:alias = binary-and | and-not | lshift | rshift | mul | div | mod;
binary-op1:alias = binary-or | xor | add | sub;
binary-op2:alias = eq | not-eq | less | less-or-eq | greater | greater-or-eq;
binary-op3:alias = logical-and;
binary-op4:alias = logical-or;

operand0:alias = primary-expression | unary-expression;
operand1:alias = operand0 | binary0;
operand2:alias = operand1 | binary1;
operand3:alias = operand2 | binary2;
operand4:alias = operand3 | binary3;
operand5:alias = operand4 | binary4;

binary0  = operand0 (binary-op0 operand0)+;
binary1  = operand1 (binary-op1 operand1)+;
binary2  = operand2 (binary-op2 operand2)+;
binary3  = operand3 (binary-op3 operand3)+;
binary4  = operand4 (binary-op4 operand4)+;
chaining = operand5 (nl* chain nl* operand5)+;

binary-expression:alias = binary0
                        | binary1
                        | binary2
                        | binary3
                        | binary4
                        | chaining;

ternary-expression = expression nl* "?" nl* expression nl* ":" nl* expression;

expression:alias = primary-expression
                 | unary-expression
                 | binary-expression
                 | ternary-expression;

if = "if" nl* expression nl* block
     (nl* "else" nl* "if" nl* expression nl* block)*
     (nl* "else" nl* block)?;

default            = "default" nl* ":";
default-line:alias = default ";"* statement?;
case               = "case" nl* expression nl* ":";
case-line:alias    = case ";"* statement?;
switch             = "switch" nl* expression? nl* "{" sep?
                     ((case-line | default-line) (sep (case-line | default-line | statement))*)?
                     sep? "}";

receive                 = "<<>" primary-expression;
receive-definition      = "let" nl* symbol nl* receive;
receive-assignment      = "set" nl* symbol nl* receive;
receive-statement:alias = receive-definition
                        | receive-assignment;
send                    = primary-expression "<<>" primary-expression;
communication:alias     = receive | receive-statement | send;

select-case            = "case" nl* communication nl* ":";
select-case-line:alias = select-case ";"* statement?;
select                 = "select" nl* "{" sep?
                         ((select-case-line | default-line)
                          (sep (select-case-line | default-line | statement))*)?
                          sep? "}";

go    = "go" nl* function-application;
defer = "defer" nl* function-application;

range-over-expression = symbol nl* "in" nl* (expression | range) | range;
loop-expression:alias = expression | range-over-expression;
loop                  = "for" ((nl* loop-expression)? nl* block | nl* block);

assign-capture:alias      = primary-expression (nl* "=")? nl* expression;
assign-capture-list:alias = assign-capture (list-sep assign-capture)*;
assign-set:alias          = "set" nl* assign-capture;
assign-eq:alias           = primary-expression nl* "=" nl* expression;
assign-group:alias        = "set" nl* "(" (list-sep assign-capture-list)? list-sep? ")";
assignment                = assign-set | assign-eq | assign-group;

value-capture-fact:alias = symbol (nl* "=")? nl* expression;
value-capture            = value-capture-fact;
mutable-capture          = "~" nl* value-capture-fact;
value-definition         = "let" nl* (value-capture | mutable-capture);
mixed-capture-list:alias = (value-capture | mutable-capture) (list-sep (value-capture | mutable-capture))*;
value-capture-list:alias = value-capture (list-sep value-capture)*;
value-definition-group   = "let" nl* "(" list-sep? mixed-capture-list? list-sep? ")";
mutable-definition-group = "let" nl* "~" nl* "(" list-sep? value-capture-list? list-sep? ")";

function-definition-fact:alias    = symbol nl* function-fact;
function-capture                  = function-definition-fact;
effect-capture                    = "~" nl* function-definition-fact;
function-definition               = "fn" nl* (function-capture | effect-capture);
function-capture-list:alias       = function-capture (list-sep function-capture)*;
mixed-function-capture-list:alias = (function-capture | effect-capture)
                                    (list-sep (function-capture | effect-capture))*;
function-definition-group         = "fn" nl* "(" list-sep?
                                    mixed-function-capture-list?
                                    list-sep? ")";
effect-definition-group           = "fn" nl* "~" nl* "(" list-sep?
                                    function-capture-list?
                                    list-sep? ")";

definition:alias = value-definition
                 | value-definition-group
                 | mutable-definition-group
                 | function-definition
                 | function-definition-group
                 | effect-definition-group;

require-inline                = ".";
require-fact                  = string
                              | (symbol | require-inline) (nl* "=")? nl* string;
require-fact-list:alias       = require-fact (list-sep require-fact)*;
require-statement:alias       = "require" nl* require-fact;
require-statement-group:alias = "require" nl* "(" list-sep?
                                require-fact-list?
                                list-sep? ")";
require                       = require-statement | require-statement-group;

export = "export" nl* definition;

simple-statement:alias       = expression
                             | send
                             | go
                             | defer
                             | assignment
                             | simple-statement-group;
simple-statement-group:alias = "(" nl* simple-statement nl* ")";
statement:alias              = simple-statement
                             | return
                             | if
                             | switch
                             | select
                             | loop
                             | definition
                             | require
                             | export
                             | statement-group;
statement-group:alias        = "(" nl* statement nl* ")";

sep:alias            = (";" | nl)+;
statement-list:alias = statement (sep statement)*;

shebang-command = [^\n]*;
shebang         = "#!" shebang-command "\n";
mml:root        = shebang? sep? statement-list? sep?;