Joseph Ferano
18db822095
spec-conditions.md §2. The same lookup as signal, and the difference is entirely what happens when the walk ends: signal returns Unit and the signalling function carries on, error has type Never and the program stops. Only a transfer gets past it, so emit puts a guard after the call and then unreachable - and flan_error cannot be marked noreturn for the same reason, it does return, on exactly one path. Being Never is what lets it stand where a value was expected, which is the fall-through shape §1's load-texture example needs and the reason it is worth having before the break loop rather than after. An unhandled one names the condition on stderr and dies the way every other trap does; flan_error is where the dev-build break loop will go. The two spellings share one AST and IR node with a kind beside them, the same shape Ast.unwrap already uses for some and try, because they differ in one decision and nothing else. test/programs/error.flan is the unhandled case, asserted on the exit code and the reason rather than through the outputs table, which only has room for a program that exits 0.
138 lines
6.0 KiB
OCaml
138 lines
6.0 KiB
OCaml
(** The AST: syntax with special forms recognised, before typing.
|
|
|
|
Sugar is gone by this point. [when], [unless], [cond] and [and]/[or] are
|
|
desugared into [If] and [Do]; they are compiler special forms until macros
|
|
arrive at milestone 5, so there is nothing to preserve for a macroexpander
|
|
to see yet.
|
|
|
|
Types here are *surface* type expressions, not resolved types. [Ptr] and
|
|
[Option] are still just names; the checker resolves them. *)
|
|
|
|
(* ── Type expressions ──────────────────────────────────────────────── *)
|
|
|
|
type texpr = { t : texpr_kind; tloc : Loc.t }
|
|
|
|
and texpr_kind =
|
|
| Tname of string (* i32 bool Cursor string *)
|
|
| Tslice of texpr (* [u8] ptr+len *)
|
|
| Tarray of len * texpr (* [4 f32] [rows [cols u32]] *)
|
|
| Tmap of texpr * texpr (* {string i32} *)
|
|
| Tapp of string * texpr list (* (Ptr Cursor) (Option f64) *)
|
|
| Tfn of texpr list * texpr (* (Fn [a a] bool) *)
|
|
|
|
(* An array length is an integer or a compile-time constant's name. *)
|
|
and len =
|
|
| Lint of int64
|
|
| Lname of string
|
|
|
|
(* ── Expressions ───────────────────────────────────────────────────── *)
|
|
|
|
type expr = { e : expr_kind; loc : Loc.t }
|
|
|
|
and expr_kind =
|
|
| Int of int64
|
|
| Float of float
|
|
| Byte of int
|
|
| Str of string
|
|
| Kw of string (* :space — coerced at typed call sites *)
|
|
| Quote of string (* 'skip-form — restart names *)
|
|
| Var of string
|
|
| Do of expr list
|
|
| Let of binding list * expr list
|
|
| If of expr * expr * expr option
|
|
| While of expr * expr list
|
|
| Return of expr option
|
|
| Set of place * expr
|
|
| Field of expr * string (* (.pos c) — auto-derefs one level *)
|
|
| Call of expr * expr list
|
|
| Match of expr * arm list
|
|
| Struct of string * (string * expr) list (* (Cursor {:src s}) *)
|
|
| Arr of expr list (* [0xE6B800FF ...] — a fixed array value *)
|
|
(* These bind names or alter control flow, so none of them can be a call. *)
|
|
| Fn of string list * expr list (* (fn [x y] ...) — non-escaping *)
|
|
| Dotimes of string * expr * expr list (* (dotimes [i n] ...) *)
|
|
| Defer of expr list (* runs on scope exit *)
|
|
| Unwrap of unwrap * expr (* (some x) / (try x) *)
|
|
(* (handler-bind [(Type [c] body ...) ...] body ...) — spec-conditions.md.
|
|
A clause binds a name for the condition, so this cannot be a call. *)
|
|
| HandlerBind of hclause list * expr list
|
|
| Signal of sigkind * expr (* (signal c) / (error c) *)
|
|
(* (restart-case body (name [] body ...) ...) and (invoke-restart 'name).
|
|
Both alter control flow, so neither can be a call. *)
|
|
| RestartCase of expr * rclause list
|
|
| InvokeRestart of string
|
|
|
|
(* Two ways to signal, because they are two different things — §1 and §2.
|
|
[signal] returns Unit whatever it finds; [error] has type Never and, with
|
|
nothing transferring, the program stops. *)
|
|
and sigkind = Ssignal | Serror
|
|
|
|
and hclause = { hty : texpr; hname : string; hbody : expr list; hloc : Loc.t }
|
|
and rclause = { rname : string; rbody : expr list; rloc : Loc.t }
|
|
|
|
(* Two unwrap operators, because they are two different things — plan.org. *)
|
|
and unwrap = Usome | Utry
|
|
|
|
and binding = { bname : string; bty : texpr option; bval : expr; bloc : Loc.t }
|
|
|
|
(* The fixed list of assignable forms — spec-memory.md. Not setf. *)
|
|
and place =
|
|
| Pvar of string
|
|
| Pfield of expr * string (* (set (.hp e) v) *)
|
|
| Pindex of expr * expr list (* (set (at grid r c) v) *)
|
|
| Pkey of expr * expr (* (set (get m k) v) *)
|
|
| Pderef of expr (* (set (deref p) v) *)
|
|
|
|
and arm = { pat : pattern; body : expr list; aloc : Loc.t }
|
|
|
|
and pattern =
|
|
| Pctor of string * string list (* (Some e) (Rect w h) None *)
|
|
| Pwild (* _ :else *)
|
|
|
|
(* ── Declarations ──────────────────────────────────────────────────── *)
|
|
|
|
type field = { fname : string; fty : texpr; floc : Loc.t }
|
|
|
|
type fn = {
|
|
name : string;
|
|
params : field list;
|
|
ret : texpr option; (* None means Unit *)
|
|
fbody : expr list;
|
|
nloc : Loc.t;
|
|
}
|
|
|
|
type decl = { d : decl_kind; dloc : Loc.t }
|
|
|
|
and decl_kind =
|
|
| Package of string
|
|
| Import of string * string (* alias, path *)
|
|
| Defalias of string * texpr
|
|
| Defstruct of string * field list
|
|
| Defunion of string * variant list
|
|
| Defn of fn
|
|
(* No body, so no [defn]: a foreign function, and the string is the C symbol
|
|
it is actually called by (plan.org, Types — [declare] is kept only where
|
|
there is no body). *)
|
|
| Declare of fn * string
|
|
(* Inline name/value pairs, as everywhere else. The members are what a
|
|
keyword at a call site resolves against. *)
|
|
| Defenum of string * (string * int64) list
|
|
(* value is optional: ZII. `uninit` opts out and is recorded as Uninit. *)
|
|
| Defvar of string * texpr option * init
|
|
| Defconst of string * texpr option * expr
|
|
|
|
and variant = { vname : string; vfields : field list; vloc : Loc.t }
|
|
|
|
and init = Zeroed | Uninit | Init of expr
|
|
|
|
(* Every top-level name a declaration introduces, whatever kind it is. There is
|
|
one top-level namespace, so this is both the set [Load] renames on an import
|
|
and the set [Check] refuses to see twice — one definition, so the two cannot
|
|
drift apart. *)
|
|
let declared_name (d : decl) =
|
|
match d.d with
|
|
| Defenum (n, _) | Defalias (n, _) | Defstruct (n, _) | Defunion (n, _)
|
|
| Defvar (n, _, _) | Defconst (n, _, _) -> Some n
|
|
| Declare (fn, _) | Defn fn -> Some fn.name
|
|
| Package _ | Import _ -> None
|