preserves/schema/schema.prs

@<EmacsMode "-*- preserves -*-">

# TODO: some kind of constants
# TODO: rename "version" to "schema-version" ?

version 1 .

Bundle = <bundle @modules Modules>.
Modules = { ModulePath: Schema ...:... }.

Schema = <schema {
  version: Version
  embeddedType: EmbeddedTypeName
  definitions: Definitions
}>.

# version 1 .
Version = 1 .

EmbeddedTypeName = #f / Ref .

Definitions = { symbol: Definition ...:... }.

Definition =
  # Pattern / Pattern / ...
  / <or [@pattern0 NamedAlternative @pattern1 NamedAlternative @patternN NamedAlternative ...]>

  # Pattern & Pattern & ...
  / <and [@pattern0 NamedPattern @pattern1 NamedPattern @patternN NamedPattern ...]>

  # Pattern
  / Pattern
.

Pattern = SimplePattern / CompoundPattern .

SimplePattern =
  # any
  / =any

  # special builtins: bool, double, int, string, bytes, symbol
  / <atom @atomKind AtomKind>

  # matches an embedded value in the input: #:p
  / <embedded @interface SimplePattern>

  # =symbol, <<lit> any>, or plain non-symbol atom
  / <lit @value any>

  # [p ...] ----> <seqof <ref p>>; see also tuplePrefix below.
  / <seqof @pattern SimplePattern>

  # #{p} ----> <setof <ref p>>
  / <setof @pattern SimplePattern>

  # {k: v, ...:...} ----> <dictof <ref k> <ref v>>
  / <dictof @key SimplePattern @value SimplePattern>

  # symbol, symbol.symbol, symbol.symbol.symbol, ...
  / Ref
.

CompoundPattern =
  # <label a b c> ----> <rec <lit label> <tuple [<ref a> <ref b> <ref c>]>>
  # except for record labels
  # <<rec> x y> ---> <rec <ref x> <ref y>>
  / <rec @label NamedPattern @fields NamedPattern>

  # [a b c] ----> <tuple [<ref a> <ref b> <ref c>]>
  / <tuple @patterns [NamedPattern ...]>

  # [a b c ...] ----> <tuplePrefix [<ref a> <ref b>] <seqof <ref c>>>
  # TODO: [@fixed0 NamedPattern @fixedN NamedPattern ...]
  / <tuplePrefix @fixed [NamedPattern ...] @variable NamedSimplePattern>

  # {a: b, c: d} ----> <dict {a: <ref b>, c: <ref d>}>
  / <dict @entries DictionaryEntries>
.

DictionaryEntries = { any: NamedSimplePattern ...:... }.

AtomKind = =Boolean / =Double / =SignedInteger / =String / =ByteString / =Symbol .

NamedAlternative = [@variantLabel string @pattern Pattern].

NamedSimplePattern = @named Binding / @anonymous SimplePattern .
NamedPattern = @named Binding / @anonymous Pattern .

Binding = <named @name symbol @pattern SimplePattern>.

Ref = <ref @module ModulePath @name symbol>.
ModulePath = [symbol ...].