IDENT  : (LETTER | '_') (LETTER | DIGIT | '_')*
QIDENT : IDENT ('.' IDENT)*
CIDENT : '?' IDENT

LITERAL : STR_LIT | BIT_LIT | NUM_LIT
STR_LIT : '"' ((!('"' | '\\' | '\n' | '\r') ANY_CHAR) | ('\\' ANY_CHAR))* '"'
BIT_LIT : 'false' | 'true'
NUM_LIT : DEC_LIT
        | HEX_LIT
        | BIN_LIT
        | NAT_LIT
        | NEG_LIT
DEC_LIT : '-'? DIGIT+ ('.' DIGIT+)? ('e' | 'E') '-'? (DIGIT+ ('.' DIGIT+)?)
        | '-'? DIGIT+ '.' DIGIT+
HEX_LIT : '0x' (DIGIT | 'a' | 'A' | 'b' | 'B' | 'c' | 'C' | 'd' | 'D' | 'e' | 'E' | 'f' | 'F')+
BIN_LIT : '0b' ('0' | '1')+
NAT_LIT : DIGIT+
NEG_LIT : '-' DIGIT+

MODULE : 'module' QIDENT IMPORT* DECL*

IMPORT : 'import' QIDENT '(' IDENT (',' IDENT)* ')'
       | 'import' QIDENT 'as' IDENT

DECL : DECL_FUNCTION
     | DECL_TRANSFORM
     | DECL_DERIVE_TRANSFORM
     | DECL_ANNOTATION
     | ANNOTATION* ANNOTATED_DECL
     | DECL_CONST

ANNOTATED_DECL : DECL_STRUCT
               | DECL_NEWTYPE
               | DECL_VARIANT
               | DECL_ENUM
               | DECL_TYPE_ALIAS

DECL_ANNOTATION  : 'annotation' IDENT ('(' PARAMS ')')? ('|' ANNOTATION_SCOPE (' ' ANNOTATION_SCOPE)* '|')?
ANNOTATION_SCOPE : 'EnumValue'
                 | 'Enum'
                 | 'Struct'
                 | 'Field'
                 | 'VariantConstructor'
                 | 'Variant'
                 | 'Newtype'
                 | 'TypeAlias'

DECL_CONST : 'const' IDENT ':' TYPE '=' EXP ';'

DECL_STRUCT      : STRUCT_MODIFIERS 'struct' IDENT ('extends' QIDENT)? '{' FIELD* STRUCT_PROPERTY* '}'
STRUCT_MODIFIERS : ('abstract'? 'extensible')? 'message'?
FIELD            : ANNOTATION* IDENT ':' TYPE ';'
STRUCT_PROPERTY  : 'assert' EXP ';'

DECL_NEWTYPE : 'newtype' IDENT '{' FIELD STRUCT_PROPERTY* '}'

DECL_VARIANT        : 'message'? 'variant' IDENT '{' VARIANT_CONSTRUCTOR+ '}'
VARIANT_CONSTRUCTOR : ANNOTATION* IDENT '(' (TYPE (',' TYPE)*)? ')' ';'

DECL_ENUM  : 'enum' IDENT TYPE '{' ENUM_VALUE+ '}'
ENUM_VALUE : ANNOTATION* IDENT '=' LITERAL ';'

DECL_TYPE_ALIAS : 'type' IDENT '=' TYPE ';'

ANNOTATION : '@' QIDENT '(' EXP (',' EXP)* ')'
           | '@' QIDENT

DECL_FUNCTION : 'function' IDENT '(' PARAMS ')' '->' TYPE BODY

DECL_TRANSFORM : 'transform' IDENT '(' PARAMS ')' '->' TYPE GIVEN_CLAUSE? BODY

DECL_DERIVE_TRANSFORM : 'derive' 'transform' IDENT '(' PARAMS ')' '->' TYPE GIVEN_CLAUSE? (';' | BODY)

PARAMS : (PARAM (',' PARAM)*)?
PARAM  : IDENT ':' TYPE

GIVEN_CLAUSE : 'given' '(' CTX_PARAMS ')'
CTX_PARAMS   : CTX_PARAM (',' CTX_PARAM)*
CTX_PARAM    : CIDENT ':' TYPE

BODY : '=' EXP ';'
     | BLOCK

BLOCK : '{' STMT* EXP ';' '}'

EXP  : 'if' EXP 'then' EXP 'else' EXP
     | 'try' EXP
     | 'map' '(' LET_PATTERN 'in' EXP ')' BLOCK
     | 'filter' '(' LET_PATTERN 'in' EXP ')' BLOCK
     | 'fold' '(' LET_PATTERN '=' EXP ';' LET_PATTERN 'in' EXP ')' BLOCK
     | EXP1 (('^' | '||' | '&&') EXP1)*
EXP1 : EXP2 (('>' | '>=' | '<' | '<=' | '==' | '!=') EXP2)*
EXP2 : EXP3 ('++' EXP3)*
EXP3 : EXP4 (('+' | '-') EXP4)*
EXP4 : EXP5 (('*' | '/' | '%') EXP5)*
EXP5 : ('!' | '-')* EXP6
EXP6 : EXP7 (':' TYPE)?
EXP7 : EXP8 ('.' IDENT | '[' EXP ']' | '[' EXP '..' EXP ']')*
EXP8 : '(' EXP (',' EXP)* ')'
     | BLOCK
     | 'match' '(' EXP ')' '{' (MATCH_PATTERN '=>' EXP ';')+ '}'
     | 'value_cast' '<' TYPE '>' '(' EXP ')'
     | 'value_cast?' '<' TYPE '>' '(' EXP ')'
     | QIDENT '(' EXP (',' EXP)* ')' ('giving' '(' EXP (',' EXP)* ')')?
     | QIDENT '{' EXP '}'
     | QIDENT '{' STRUCT_BUILDER* '}'
     | '[' (EXP (',' EXP)*)? ']'
     | '[' EXP COMP_CHAIN ('zip' COMP_CHAIN)* ']'
     | LITERAL
     | QIDENT
     | CIDENT

STMT : 'let' LET_PATTERN '=' EXP ';'
     | 'assert' EXP ';'

LET_PATTERN : '(' LET_PATTERN (',' LET_PATTERN)+ ')' (':' TYPE)?
            | IDENT (':' TYPE)?

MATCH_PATTERN  : MATCH_PATTERN1 (':' TYPE | 'as' TYPE)?
MATCH_PATTERN1 : '(' MATCH_PATTERN (',' MATCH_PATTERN)+ ')'
               | '[' (MATCH_PATTERN (',' MATCH_PATTERN)*)? ']'
               | 'some' '(' MATCH_PATTERN ')'
               | 'none'
               | QIDENT '(' (MATCH_PATTERN (',' MATCH_PATTERN)*)? ')'
               | LITERAL
               | '_'
               | QIDENT

COMP_CHAIN  : COMP_CLAUSE+
COMP_CLAUSE : 'if' EXP
            | 'for' LET_PATTERN 'in' EXP
            | 'scan' LET_PATTERN '=' EXP 'in' EXP
            | 'let' LET_PATTERN '=' EXP

TYPE  : TYPE1 ('[' ']')*
TYPE1 : '(' TYPE (',' TYPE)+ ')'
      | 'Optional' '<' TYPE '>'
      | INT_TYPE
      | UINT_TYPE
      | 'bit'
      | 'float32'
      | 'float64'
      | 'string'
      | QIDENT