3.0.1

CHANGES:

• Language:

  • Improve error message for non deterministic atom
  • Fix overlap check for uvar F L as X
  • Fix allow symbol as an identifier

• Compiler:

  • Fix build reproducibility

3.0.0

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Language:

  • A functional predicate is a predicate that does not leave choice points
    for any of its calls. A functional predicate can have preconditions, eg
    map is functional if the higher order argument also is. Functional
    predicates (with preconditions) can be miscalled, in that case they behave
    as relations.
  • The matching operator used for input arguments is now also available as a
    builtin predicate named pattern_match.

• API:

  • New Utils.ground_check and Utils.cmp_term (already available as builtins)
  • Change Constants.declare_global_symbol takes an optional variant argument.

• Parser:

  • The fprop keyword is akin to prop but signals the predicate is functional
  • The :functional attribute flags predicates as functional (equivalent to func ...).
  • Dedicated syntax for functional signatures:
    func name(comma_sep(types_of_inputs)* [-> comma_sep(types_of_outputs*)].
    Example: The signature of map is func map list A, (func A -> B) -> list B
  • New [external] symbol name : type [= "variant"] is a synonim of type and can be
    used to ascribe a type to a symbol. External symbols must be matched by
    a declaration in OCaml, and when the symbol is overloaded the variant
    label is used for the matching (additionally to the name).

• Compiler:

  • The type checker is in charge of resolving all symbols, overloaded or not,
    to a Symbol.t datatype that gathers the Loc.t where it is defined
    (and it can be defined at multiple places, e.g. OCaml + Elpi, or twice
    in Elpi). This data can be used to implement jump-to-def and the like in
    modern UIs.
  • The determinacy_checker statically analyzes whether a predicate labeled
    as functional adheres to its signature.
  • The elaboration of {spilling} has been moved to a dedicated file.
  • CHR rules are typechecked (finally)
  • Macros are typechecked. This paves the way to make them live in name
    spaces and possibly globally available, but it is not implemented yet.

• Runtime:

  • Builtin predicates now have a dedicated node when they are part of the
    Elpi language, i.e. Cut, And, Impl, RImpl, Pi, Sigma, Eq, Match, Findall,
    Delay.
  • Symbols part of the Elpi language (other than the builtins) also have
    a dedicated status, i.e. As, Uv, ECons, ENil although As and Uv do not
    have a dedicated node in the AST, while ENil and ECons do have it.

2.0.7

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Parser:

  • New elpi:if version <name> <op> <ma>.<mi>.<p>

• API:

  • New Setup.init takes a ?versions dictionary to declare versions
    of external components
  • New Utils.parse_version

2.0.6

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Compiler:
  • Store timing info only optionally to restore build reproducibility
  • Fix collision between kinds and types in namespace handling

2.0.5

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Parser:
  • Fix loc issues involving quotations

2.0.4

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Type Checker:
  • Fix caching issue, units are now type checked every time they are processed

2.0.3

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Parser:
  • Fix parsing of infix ==> so that A,B ==> C,D means A, (B => (C,D))
    as it is intended to be.

2.0.2

CHANGES:

Requires Menhir 20211230 and OCaml 4.13 or above.

• Really fix tests on 32 bits systems

2.0.1

CHANGES:

Requires Menhir 20211230 and OCaml 4.08 or above.

• Fix tests on 32 bits systems

2.0.0

CHANGES:

Requires Menhir 20211230 and OCaml 4.08 or above.

• Compiler:

  • Change the pipeline completely to make unit relocation unnecessary. Current
    phases are (roughly):

    1. Ast.program —[RecoverStructure]—> Ast.Structured.program
    2. Ast.Structured.program —[Scope,Quotation,Macro]—> Scoped.program (aka API.Compile.scoped_program)
    3. Scoped.program —[Flatten]—> Flat.program
    4. Flat.program —[Check]—> CheckedFlat.program (aka API.Compile.compilation_unit)
    5. CheckedFlat.program —[Spill,ToDbl]—> Assembled.program

    Steps 4 and 5 operate on a base, that is an Assembled.program being
    extended. ToDbl is in charge of allocating constants (numbers) for global
    names and takes place when the unit is assembled on the base. These
    constants don't need to be relocated as in the previous backend that
    would allocate these constants much earlier.

  • Change compilation units can declare new builtin predicates

  • Fix macros are hygienic

  • New type checker written in OCaml. The new type checker is faster,
    reports error messages with a precise location and performs checking
    incrementally when the API for separate compilation is used.
    The new type checker is a bit less permissive since the old one would
    merged together all types declaration before type checking the entire
    program, while the new one type checks each unit using the types declared
    inside the unit or declared in the base it extends, but not the types
    declared in units that (will) follow it.

  • Remove the need of typeabbrv string (ctype "string") and similar

  • New type check types and kinds (used to be ignored).

• API:

  • Change quotations generate Ast.Term.t and not RawData.t. The data
    type Ast.Term.t contains locations (for locating type errors) and
    has named (bound) variables and type annotations in Ast.Type.t.
  • New Compile.extend_signature and Compile.signature to extend a
    program with the signature (the types, not the code) of a unit
  • New Ast.Loc.t carries a opaque payload defined by the host application
  • Remove Query, only RawQuery is available (or Compile.query)

• Parser:

  • Remove legacy parser
  • New % elpi:if version op A.B.C and % elpi:endif lexing directives
  • New warning for A => B, C to be disabled by putting parentheses
    around A => B.

• Language:

  • New infix ==> standing for application but with "the right precedence™",
    i.e. A ==> B, C means A => (B, C).
  • New pred is allowed in anonymous predicates, eg:
    pred map i:list A, i:(pred i:A, o:B), o:list B declares that the first
    argument of map is a predicate whose first argument is in input and
    the second in output. Currently the mode checker is still in development,
    annotations for higher order arguments are ignored.
  • New attribute :functional can be passed to predicates (but not types).
    For example, :functional pred map i:list A, i:(:functional pred i:A, o:B), o:list B
    declares map to be a functional predicate iff its higher order argument is
    functional. Currently the determinacy checker is still in development, these
    annotations are ignored.
  • New func keyword standing for :functional pred. The declaration above
    can be shortened to func map i:list A, i:(func i:A, o:B), o:list B.
  • New type annotations on variables quantified by pi as in pi x : term \ ...
  • New type casts on terms, as in f (x : term)
  • New attribute :untyped to skip the type checking of a rule.

• Stdlib:

  • New std.list.init N E L builds a list L = [E, ..., E] with length N
  • New std.list.make N F L builds the list L = [F 0, F 1, ..., F (N-1)]
  • New triple data type with constructor triple and projections triple_1...

• Builtins:

  • Remove string_to_term, read, readterm, quote_syntax

• REPL:

  • Remove -no-tc, -legacy-parser, -legacy-parser-available
  • New -document-infix-syntax