Compact Grammar

Compact language version 0.13.0.

Notational note: In the grammar productions below, ellipses are used to specify repetition. The notation X ... X, where X is a grammar symbol, represents zero or more occurrences of X. The notation X s ... s X, where X is a grammar symbol and s is a separator such as a comma or or semicolon, represents zero or more occurrences of X separated by s. In either case, when the ellipsis is marked with the superscript 1, the notation represents a sequence containing at least one X. For example, id … id represents zero or more ids, and expr , …¹ , expr represents one or more comma-separated exprs.

identifier (id, module-name, function-name, struct-name, enum-name, contract-name, tvar-name)

identifiers have the same syntax as Typescript identifiers

adt-identifier (adt-name)

identifier that names one of the Ledger ADTs

field-literal (nat)

a field literal is 0 or a natural number formed from a sequence of digits starting with 1-9, e.g. 723, whose value does not exceed the maximum field value

string-literal (str, file)

a string literal has the same syntax as a Typescript string

version-literal (version)

a version literal takes the form nat or nat.nat or nat.nat.nat, e.g., 1.2 or 1.2.3, representing major, minor, and bugfix versions

Compact (program)

program →  pelt … pelt

Program-element (pelt)

pelt →  pragma
 →  incld
 →  mdefn
 →  idecl
 →  xdecl
 →  ldecl
 →  lconstructor
 →  cdefn
 →  edecl
 →  wdecl
 →  ecdecl
 →  struct
 →  enumdef

Pragma (pragma)

pragma →  pragma  id  version-expr  ;

Version-expression (version-expr)

The productions on each line of this group have lower precedence than those on the lines that follow.

version-expr →  version-expr || version-term
→  version-expr && version-term
→  version-term

Version-Term (version-term)

version-term →  version-atom
 →  !  version-term
 →  <  version-atom
 →  <=  version-atom
 →  >=  version-atom
 →  >  version-atom
 →  (  version-expr  )

Version-Atom (version-atom)

version-atom →  nat
 →  version

Include (incld)

incld →  include  file  ;

Module-definition (mdefn)

mdefn →  exportopt  module  module-name  tparamsopt  {  pelt … pelt  }

Type-params (tparams)

tparams →  <  type-param , … , type-param  >

Type-param (type-param)

type-param →  #  tvar-name
 →  tvar-name

Import-declaration (idecl)

idecl →  import  import-name  targsopt  prefixopt  ;

Import-Name (import-name)

import-name →  id
 →  file

Type-args (targs)

targs →  <  targ , … , targ  >

Import-prefix (prefix)

prefix →  prefix  id

Export (export)

export →  export

Sealed (sealed)

sealed →  sealed

Pure (pure)

pure →  pure

Export-declaration (xdecl)

xdecl →  export  {  id , … , id  }  ;opt

Ledger-Declaration (ldecl)

ldecl →  exportopt  sealedopt  ledger  id  :  ledger-adt  ;

Ledger-Constructor (lconstructor)

lconstructor →  constructor  (  arg , … , arg  )  block  ;opt

Circuit-definition (cdefn)

cdefn →  exportopt  pureopt  circuit  function-name  tparamsopt  (  arg , … , arg  )  :  return-type  block

External-declaration (edecl)

edecl →  exportopt  circuit  id  tparamsopt  (  arg , … , arg  )  :  return-type  ;

Witness-declaration (wdecl)

wdecl →  exportopt  witness  id  tparamsopt  (  arg , … , arg  )  :  return-type  ;

External-contract-declaration (ecdecl)

ecdecl →  exportopt  contract  contract-name  {  ecdecl-circuit … ecdecl-circuit  }  ;opt

External-contract-circuit (ecdecl-circuit)

ecdecl-circuit →  pureopt  circuit  id  (  arg , … , arg  )  :  return-type  ;

Structure-definition (struct)

struct →  exportopt  struct  struct-name  tparamsopt  {  arg ; … ; arg  ;opt  }
 →  exportopt  struct  struct-name  tparamsopt  {  arg , … , arg  ,opt  }

Enum-definition (enumdef)

enumdef →  exportopt  enum  enum-name  {  id , …¹ , id  ,opt  }

Ledger-adt (ledger-adt)

Midnight ledger ADTs are described here.

ledger-adt →  adt-name  adt-argsopt

Ledger-adt-args (adt-args)

adt-args →  <  ledger-adt-arg , …¹ , ledger-adt-arg  >

Ledger-ADT-Arg (ledger-adt-arg)

ledger-adt-arg →  nat
 →  adt-type

Ledger-ADT-Type (adt-type)

adt-type →  type
 →  ledger-adt

Argument (arg)

arg →  id  :  type

Return-Type (return-type)

return-type →  Void
 →  type

Type (type)

type →  tref
 →  Boolean
 →  Field
 →  Uint  <  tsize  >
 →  Uint  <  tsize  ..  tsize  >
 →  Bytes  <  tsize  >
 →  Opaque  <  str  >
 →  Vector  <  tsize  ,  type  >

Type-ref (tref)

tref →  id  targsopt

Type-size (tsize)

tsize →  nat
 →  id

Type-argument (targ)

targ →  nat
 →  type

Block (block)

block →  {  stmt … stmt  }

Statement (stmt)

stmt →  expr  =  expr  ;
 →  expr  +=  expr  ;
 →  expr  -=  expr  ;
 →  expr-seq  ;
 →  return  expr-seq  ;
 →  return  ;
 →  if  (  expr-seq  )  stmt  else  stmt
 →  if  (  expr-seq  )  stmt
 →  for  id  =  nat  to  nat  do  stmt
 →  for  id  in  expr-seq  do  stmt
 →  assert  expr  str  ;
 →  const  id  =  expr  ;
 →  const  id  :  adt-type  =  expr  ;
 →  block

Expression-Sequence (expr-seq)

expr-seq →  expr
 →  expr , …¹ , expr  ,  expr

Expression (expr)

expr →  expr0  ?  expr  :  expr
 →  expr0

Function (fun)

fun →  id  targsopt
 →  (  var-or-arg , … , var-or-arg  )  return-type-declopt  =>  block
 →  (  var-or-arg , … , var-or-arg  )  return-type-declopt  =>  expr
 →  (  fun  )

Return-Type-Declaration (return-type-decl)

return-type-decl →  :  return-type

Variable-or-Argument (var-or-arg)

var-or-arg →  id
 →  arg

Expression0 (expr0)

The productions on each line of this group have lower precedence than those on the lines that follow.

expr0 →  expr0 || expr1
→  expr0 && expr1
→  expr0 == expr1  |  expr0 != expr1
→  expr1 < expr1  |  expr1 > expr1  |  expr1 <= expr1  |  expr1 >= expr1
→  expr1

Expression1 (expr1)

expr1 →  expr2  tail-expr1

Expression1-tail (tail-expr1)

tail-expr1 →  (empty)
 →  as  type  tail-expr1

Expression2 (expr2)

The productions on each line of this group have lower precedence than those on the lines that follow.

expr2 →  expr2 + expr3  |  expr2 - expr3
→  expr2 * expr3
→  expr3

Expression3 (expr3)

expr3 →  !  expr3
 →  expr4

Expression4 (expr4)

expr4 →  term  tail-expr4

Expression4-tail (tail-expr4)

tail-expr4 →  (empty)
 →  [  nat  ]  tail-expr4
 →  .  id  tail-expr4
 →  .  id  (  expr , … , expr  )  tail-expr4

Term (term)

term →  lit
 →  id
 →  default  <  type  >
 →  default  <  ledger-adt  >
 →  map  (  fun  ,  expr , …¹ , expr  )
 →  fold  (  fun  ,  expr  ,  expr , …¹ , expr  )
 →  fun  (  expr , … , expr  )
 →  tref  {  new-field , … , new-field  }
 →  [  expr , … , expr  ,opt  ]
 →  (  expr-seq  )

New-Field (new-field)

new-field →  expr
 →  id  :  expr
 →  ...  expr

Literal (lit)

lit →  true
 →  false
 →  nat
 →  str
 →  pad  (  nat  ,  str  )