ail: embed Form-A spec in merge-prose prompt (iter 20f)

Closes a design hole shipped in 20d: the merge-prose prompt instructed
the LLM to emit JSON-AST and gave a 12-line schema-essentials reminder.
JSON-AST is the canonical hashable artefact, not a writing surface; the
reminder was not a language spec. Foreign LLMs had no realistic shot.

20f makes two coupled changes:

1) The LLM now emits Form-A (the canonical authoring surface fixed by
   Decision 6). merge-prose loads the original via ailang_core::load_module
   and re-renders via ailang_surface::print before embedding (round-trip
   is a gating contract on the surface crate, so this is lossless). The
   user runs `ail parse foo.new.ailx` to recover JSON, then `ail check`.

2) crates/ailang-core/specs/form_a.md is the complete LLM-targeted
   Form-A specification — grammar, every term/pattern/type/def keyword,
   schema invariants, pitfall catalogue, four few-shot modules from
   examples/*.ailx. Exported as ailang_core::FORM_A_SPEC via include_str!
   and embedded verbatim in every merge-prose prompt.

Drift detection in crates/ailang-core/tests/spec_drift.rs: every variant
of Term, Pattern, Type, Def, Literal is reached via exhaustive `match`.
The arms are not the assertion — adding a new variant without updating
the match is a compile error before the test runs. Once matched, an
anchor string is asserted to appear in FORM_A_SPEC. 8 tests, all green.

The hand-written + mechanical-drift-test combo addresses the user's
"distance to code is too big" concern about a docs-only spec. Generator
overkill rejected: structural drift is mechanically caught, but prose
explanation, schema-invariant catalogue, pitfall list, and few-shot
corpus cannot be emitted from AST shape alone.

Tests:
  - ailang-core: +8 spec_drift tests; existing 12 unchanged
  - ail unit (3): rewritten in lockstep — assert (own T)/(effects IO)
    landmarks, FORM-A SPECIFICATION header, FORM_A_SPEC body verbatim
  - ail e2e merge_prose_prints_framed_prompt: rewritten — assert
    `(module foo` + `FORM-A SPECIFICATION` instead of `ailang/v0`
  - Workspace: all green

Richer integration paths (LLM tool-use, MCP server, LSP) were named
in the design discussion and deferred per "kiss". All three layer
additively on the static-prompt path; static prompt remains the
lowest-common-denominator fallback.
This commit is contained in:
2026-05-08 23:31:27 +02:00
parent 8375eb81ed
commit 72626fa94f
8 changed files with 1070 additions and 197 deletions
+103 -103
View File
@@ -229,89 +229,89 @@ enum Cmd {
/// Composes the prose-round-trip prompt described in
/// `docs/PROSE_ROUNDTRIP.md`.
///
/// The two payloads — the original `.ail.json` and the edited prose —
/// are inserted verbatim between heredoc-style markers; the rest of
/// the returned string is the role-statement, contract, output spec,
/// and schema-essentials reminder that frame the LLM's task.
/// The three payloads — the AILang Form-A specification, the original
/// module rendered as Form-A, and the edited prose — are inserted
/// verbatim between heredoc-style markers. The rest of the returned
/// string is the role-statement, contract, and output spec that frame
/// the LLM's task.
///
/// Iter 20f rewrote this function: the prompt now embeds
/// [`ailang_core::FORM_A_SPEC`] (the language reference an LLM needs
/// to generate AILang from scratch) and the original module as Form-A
/// (the canonical authoring surface, Decision 6) instead of JSON-AST.
/// JSON-AST stays the canonical hashable artefact, but no human or
/// LLM should write it directly — `ail parse` converts the LLM's
/// Form-A output to JSON.
///
/// Pure: same inputs always yield the same bytes. The CLI wrapper
/// (`Cmd::MergeProse`) is just a file-reader + `print!`.
fn compose_merge_prose_prompt(orig_ail_json: &str, edited_prose: &str) -> String {
// Keep this template in lockstep with `docs/PROSE_ROUNDTRIP.md` —
// the doc reproduces the literal text so a human can assemble the
// same prompt by hand.
format!(
/// (`Cmd::MergeProse`) is just file-reading + Form-A render + `print!`.
fn compose_merge_prose_prompt(original_form_a: &str, edited_prose: &str) -> String {
// Built with String::push_str rather than format!() because
// `FORM_A_SPEC` contains literal `{` and `}` from embedded JSON
// examples, which would break format!'s placeholder escaping.
let mut out = String::new();
out.push_str(
"You are integrating prose edits back into an AILang module.
ROLE
Your job is to produce an updated AILang JSON-AST (.ail.json) that
reflects the human's prose edits while preserving the load-bearing
semantic detail from the original .ail.json.
Your job is to produce an updated AILang module in Form-A (an .ailx
file) that reflects the human's prose edits while preserving the
load-bearing semantic detail from the original module.
CONTRACT
The prose is the source of intent: the human edited it to express
what the program should now do. The original .ail.json carries
what the program should now do. The original Form-A carries
load-bearing detail that the prose surface elides — preserve those
details unless the prose explicitly contradicts them. Specifically:
- Mode annotations on fn parameters (`own T`, `borrow T`).
These are hard contracts (memory model). The prose shows them,
but if the prose is ambiguous, default to the original.
- Effect annotations on return types (`with IO`, `with Diverge`).
Prose shows these too, but again: if uncertain, keep what the
original had.
- `tail` flags on calls. The prose prints `tail f(x)`; if the
edit moved a call, decide whether the new position is still in
tail position and flag accordingly.
- Doc strings (`///` lines).
- Type annotations on signatures and lambdas.
- Mode annotations on fn parameters (`(own T)`, `(borrow T)`).
These are hard contracts (memory model). The prose shows them
as `own T` / `borrow T`; the Form-A wraps them. If the prose is
ambiguous, default to the original.
- Effect annotations on return types (`(effects IO)`,
`(effects Diverge)`). Prose shows these as `with IO` etc.; if
uncertain, keep what the original had.
- `tail` flags on calls. The prose prints `tail f(x)`; the Form-A
keyword is `(tail-app f x)`. If the edit moved a call, decide
whether the new position is still in tail position.
- Doc strings (`(doc \"...\")` clauses; prose shows them as `///`).
- `(suppress (code ...) (because ...))` clauses (prose shows them
as `// @suppress code: reason`). The `because` MUST be non-empty.
- Constructor names and arities (the prose `Cons(h, t)` must
round-trip to a `Term::Ctor` with the right `type` field).
round-trip to `(term-ctor TYPE Cons h t)` with the right TYPE).
OUTPUT
Output ONLY the new .ail.json bytes. No commentary, no markdown
fences, no preamble or postscript. The output must be valid JSON
parsable by `ail parse` (i.e. by `serde_json` against the
`ailang/v0` schema). The first byte should be `{{` and the last
non-whitespace byte should be `}}`.
Output ONLY the new Form-A bytes. No commentary, no markdown fences,
no preamble or postscript. The output must be parseable by
`ail parse` (it will be piped to that command immediately). The first
non-whitespace byte should be `(` (the opening of `(module ...)`)
and the last non-whitespace byte should be `)`.
SCHEMA ESSENTIALS
A full reference lives in docs/DESIGN.md (\"Data model (MVP)\"). The
shape is:
- Module: {{ \"schema\": \"ailang/v0\", \"name\": ..., \"imports\": [...],
\"defs\": [...] }}
- Defs are tagged via `kind` (\"fn\" | \"type\" | \"const\").
- Types are tagged via `k` (\"con\" | \"fn\" | \"var\" | \"forall\").
- Terms are tagged via `t` (\"lit\" | \"var\" | \"app\" | \"let\" | \"if\"
| \"do\" | \"ctor\" | \"match\" | \"lam\" | \"seq\").
- Patterns are tagged via `p` (\"var\" | \"lit\" | \"ctor\" | \"wild\").
- On `fn-type`: `param_modes` (one of \"own\"/\"borrow\" per
parameter) and `effects` are mandatory. `ret_mode` is mandatory
when the return type carries a mode.
- Constructor application uses `Term::Ctor` (`\"t\": \"ctor\"`,
fields `type` + `ctor` + `args`), NOT `Term::App`. The prose
surface elides the `type` tag (`Cons(h, t)` instead of
`(term-ctor IntList Cons h t)`) — re-introduce it.
- Base type names that appear bare in prose (`Int`, `Bool`,
`Unit`, user types like `IntList`) must be wrapped as
`{{\"k\": \"con\", \"name\": \"Int\"}}` etc. in the JSON.
ORIGINAL .ail.json
<<<ORIGINAL_AIL_JSON
{orig}
ORIGINAL_AIL_JSON
EDITED PROSE
<<<EDITED_PROSE
{edited}
EDITED_PROSE
Emit the updated .ail.json now.
",
orig = orig_ail_json,
edited = edited_prose,
)
);
out.push_str("FORM-A SPECIFICATION\n");
out.push_str("<<<FORM_A_SPEC\n");
out.push_str(ailang_core::FORM_A_SPEC);
if !ailang_core::FORM_A_SPEC.ends_with('\n') {
out.push('\n');
}
out.push_str("FORM_A_SPEC\n\n");
out.push_str("ORIGINAL MODULE (Form-A)\n");
out.push_str("<<<ORIGINAL_FORM_A\n");
out.push_str(original_form_a);
if !original_form_a.ends_with('\n') {
out.push('\n');
}
out.push_str("ORIGINAL_FORM_A\n\n");
out.push_str("EDITED PROSE\n");
out.push_str("<<<EDITED_PROSE\n");
out.push_str(edited_prose);
if !edited_prose.ends_with('\n') {
out.push('\n');
}
out.push_str("EDITED_PROSE\n\n");
out.push_str("Emit the updated Form-A module now.\n");
out
}
fn main() -> Result<()> {
@@ -418,15 +418,18 @@ fn main() -> Result<()> {
print!("{}", ailang_prose::module_to_prose(&m));
}
Cmd::MergeProse { original, edited } => {
// Iter 20d: read both inputs verbatim, compose the prompt,
// print to stdout. No schema validation here — `ail check`
// exists for that purpose, and merge-prose is intentionally
// a pure prompt-shaper.
let orig = std::fs::read_to_string(&original)
.with_context(|| format!("reading {}", original.display()))?;
// Iter 20f: load the original .ail.json, render it as
// Form-A (the canonical authoring surface, Decision 6),
// and embed *that* in the prompt — not the raw JSON-AST.
// Form-A is the form an LLM should produce; JSON is the
// hashable artefact, not the writing surface. The prose
// file is embedded byte-for-byte.
let module = ailang_core::load_module(&original)
.with_context(|| format!("loading {}", original.display()))?;
let original_form_a = ailang_surface::print(&module);
let prose = std::fs::read_to_string(&edited)
.with_context(|| format!("reading {}", edited.display()))?;
print!("{}", compose_merge_prose_prompt(&orig, &prose));
print!("{}", compose_merge_prose_prompt(&original_form_a, &prose));
}
Cmd::Describe { path, name, json, workspace } => {
if workspace {
@@ -1911,22 +1914,28 @@ fn build_to(
mod tests {
use super::compose_merge_prose_prompt;
/// The composed prompt must contain both inputs byte-for-byte —
/// the LLM has to see exactly what the user wrote, with no
/// re-encoding or stripping.
/// The composed prompt must contain all three payloads
/// byte-for-byte — the LLM has to see exactly what the user wrote,
/// the original module's Form-A bytes, and the embedded spec, with
/// no re-encoding or stripping.
#[test]
fn merge_prose_prompt_contains_both_inputs_verbatim() {
let orig = "{\"schema\":\"ailang/v0\",\"name\":\"foo\",\"defs\":[]}";
let prose = "// module foo\n\nfn bar() -> Int { 42 }\n";
fn merge_prose_prompt_contains_all_payloads_verbatim() {
let orig = "(module foo\n (fn main\n (type (fn-type (params) (ret (con Unit))))\n (params)\n (body (lit-unit))))\n";
let prose = "// module foo\n\nfn main() -> Unit { () }\n";
let out = compose_merge_prose_prompt(orig, prose);
assert!(
out.contains(orig),
"prompt missing original .ail.json verbatim; got:\n{out}"
"prompt missing original Form-A verbatim; got:\n{out}"
);
assert!(
out.contains(prose),
"prompt missing edited prose verbatim; got:\n{out}"
);
// The full FORM_A_SPEC must appear in the prompt.
assert!(
out.contains(ailang_core::FORM_A_SPEC),
"prompt missing the FORM_A_SPEC body verbatim"
);
}
/// The framing sections must all be present so the LLM has the
@@ -1934,44 +1943,35 @@ mod tests {
/// landmark from each section.
#[test]
fn merge_prose_prompt_has_all_framing_sections() {
let out = compose_merge_prose_prompt("{}", "");
// Role statement.
let out = compose_merge_prose_prompt("(module x)", "");
assert!(
out.contains("ROLE")
&& out.contains("integrating prose edits"),
out.contains("ROLE") && out.contains("Form-A"),
"prompt missing ROLE section"
);
// Contract about preserving load-bearing detail.
assert!(
out.contains("CONTRACT")
&& out.contains("preserve those")
&& out.contains("`own T`")
&& out.contains("`with IO`"),
&& out.contains("(own T)")
&& out.contains("(effects IO)"),
"prompt missing CONTRACT section"
);
// Output spec — JSON only, no fences, no commentary.
assert!(
out.contains("OUTPUT")
&& out.contains("ONLY")
&& out.contains("no markdown"),
"prompt missing OUTPUT section"
);
// Schema-essentials reminder + DESIGN.md pointer.
// The embedded language spec, by section header.
assert!(
out.contains("SCHEMA ESSENTIALS")
&& out.contains("docs/DESIGN.md")
&& out.contains("`kind`")
&& out.contains("`k`")
&& out.contains("`t`")
&& out.contains("`p`")
&& out.contains("param_modes")
&& out.contains("Term::Ctor"),
"prompt missing SCHEMA ESSENTIALS section"
out.contains("FORM-A SPECIFICATION"),
"prompt missing FORM-A SPECIFICATION header"
);
// Heredoc-style markers around both payloads.
// Heredoc-style markers around all three payloads.
assert!(
out.contains("<<<ORIGINAL_AIL_JSON")
&& out.contains("ORIGINAL_AIL_JSON\n")
out.contains("<<<FORM_A_SPEC")
&& out.contains("FORM_A_SPEC\n")
&& out.contains("<<<ORIGINAL_FORM_A")
&& out.contains("ORIGINAL_FORM_A\n")
&& out.contains("<<<EDITED_PROSE")
&& out.contains("EDITED_PROSE\n"),
"prompt missing payload markers"
@@ -1982,7 +1982,7 @@ mod tests {
/// output.
#[test]
fn merge_prose_prompt_is_deterministic() {
let orig = "{\"x\":1}";
let orig = "(module y)";
let prose = "fn f() {}";
let a = compose_merge_prose_prompt(orig, prose);
let b = compose_merge_prose_prompt(orig, prose);
+13 -3
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@@ -2387,6 +2387,11 @@ fn merge_prose_prints_framed_prompt() {
std::fs::create_dir_all(&tmp).unwrap();
let orig_path = tmp.join("orig.ail.json");
let prose_path = tmp.join("edited.prose.txt");
// Iter 20f: merge-prose now loads the module via ailang_core,
// renders to Form-A, and embeds *that* in the prompt — so the
// input must be a well-formed ailang/v0 JSON-AST that
// load_module accepts. The schema, name, and an empty defs list
// are the minimum.
let orig_bytes =
b"{\"schema\":\"ailang/v0\",\"name\":\"foo\",\"imports\":[],\"defs\":[]}";
let prose_bytes = b"// module foo\n\nfn bar() -> Int { 42 }\n";
@@ -2410,13 +2415,18 @@ fn merge_prose_prints_framed_prompt() {
stdout.contains("integrating prose edits"),
"prompt missing role-statement landmark; got:\n{stdout}"
);
// Both inputs must round-trip into the prompt verbatim.
// Original module is now embedded as Form-A, not JSON.
assert!(
stdout.contains("ailang/v0"),
"prompt missing original .ail.json content"
stdout.contains("(module foo"),
"prompt missing original Form-A content; got:\n{stdout}"
);
assert!(
stdout.contains("fn bar() -> Int { 42 }"),
"prompt missing edited prose content"
);
// The embedded spec must be present.
assert!(
stdout.contains("FORM-A SPECIFICATION"),
"prompt missing FORM-A SPECIFICATION section"
);
}
+397
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@@ -0,0 +1,397 @@
# AILang Form-A — LLM authoring specification
Form-A is the canonical textual surface of AILang. It is the form that
LLMs generate when asked to produce or edit AILang code, and the form
that `ail parse <file>.ailx` reads. The inverse direction — printing
JSON-AST as Form-A — is `ail render <file>.ail.json`. Round-trip
through this pair is the gating contract: `parse(render(m)) == m`
for every well-formed module.
This document is the **complete LLM-targeted specification**. If you
are an LLM and this is in your context, you have everything you need
to produce valid Form-A. The file lives at
`crates/ailang-core/specs/form_a.md` next to the AST definitions, and
a unit test (`tests/spec_drift.rs`) walks every AST enum variant and
asserts its serde tag appears here — so this document cannot silently
fall behind the language.
## Why Form-A and not JSON
The hashable artefact is `.ail.json`, but no human or LLM should write
that directly. JSON-AST is a mechanical serialization with high
boilerplate (`{"k": "con", "name": "Int"}` per type reference, mandatory
field tags, every term wrapped). Form-A is the same information in a
Lisp-style S-expression dress that:
- omits structural noise (no field tags; positions carry meaning)
- has a real parser with positional error messages
- round-trips through `ail render``ail parse` losslessly
- is the form every existing `examples/*.ailx` is written in
LLMs generate Form-A; the toolchain converts to JSON.
## Conventions
- `NAME` is a bare identifier: letters, digits, `_`, `-`, `+`, `*`,
`/`, `<`, `>`, `=`, `!`, `?`, `%`. Cannot start with a digit.
- `STRING` is a double-quoted UTF-8 literal: `"hello"`. Backslash
escapes: `\"`, `\\`, `\n`, `\t`.
- `INT` is a signed decimal integer; leading `-` is allowed.
- Whitespace and `;`-prefixed line comments are insignificant.
- `?` after a clause means optional. `*` means zero or more.
## Module structure
```
(module NAME
IMPORT*
DEF*)
```
The module name MUST equal the file stem (`bench_list_sum.ailx`
`(module bench_list_sum ...)`).
## Imports
```
(import MODULE-NAME)
(import MODULE-NAME (as ALIAS))
```
The alias clause is optional. Imported modules are resolved relative
to the entry file's directory.
## Definitions
Three kinds, matched on the leading keyword:
### Function — `(fn ...)`
```
(fn NAME
(doc STRING)?
(suppress (code STRING) (because STRING))*
(type FN-TYPE)
(params NAME*)
(body TERM))
```
`doc` is optional but recommended — it appears in the prose projection
and helps downstream readers (human and LLM).
`suppress` clauses silence advisory diagnostics for this def. The
`code` MUST be one of the registered codes (today: `over-strict-mode`).
The `because` MUST be a non-empty justification — empty / whitespace-
only `because` is itself an error (`empty-suppress-reason`).
`type` is a `(fn-type ...)` (possibly wrapped in `(forall ...)` for
polymorphic defs). All parameters of a `(fn ...)` MUST carry a mode
annotation — see *Modes* below.
`params` is a list of bare names that bind the parameters in `body`.
The list length must match the number of params in `type`.
### Data type — `(data ...)`
```
(data NAME
(vars TYVAR+)?
(doc STRING)?
(ctor CTOR-NAME ARG-TYPE*)*)
```
`vars` makes the type polymorphic; absent means monomorphic. Each
`ctor` clause is one variant. `ARG-TYPE` is a `TYPE` — see below.
### Constant — `(const ...)`
```
(const NAME
(doc STRING)?
(type TYPE)
(body TERM))
```
## Types
Four shapes, all parenthesised except a bare type variable:
```
TYVAR-NAME ; type variable (e.g. `a`, `T`)
(con NAME TYPE-ARG*) ; type-constructor application
(fn-type (params PARAM*)
(ret RETURN-PARAM)
(effects EFFECT-NAME*)?) ; function type
(forall (vars TYVAR+) BODY-TYPE) ; polymorphic schema
```
`PARAM` and `RETURN-PARAM` are types, optionally wrapped in a mode
annotation:
```
TYPE ; implicit mode (DO NOT USE in new (fn ...) defs)
(own TYPE) ; caller transfers ownership; callee consumes
(borrow TYPE) ; caller retains ownership; callee must not consume
```
`EFFECT-NAME` is a bare identifier — currently `IO` and `Diverge`.
Effects are a set; order is irrelevant.
Built-in type-constructors: `Int`, `Bool`, `Str`, `Unit`. User ADTs
use the name from the `(data ...)` def.
Examples:
```
(con Int)
(con List (con Int))
(fn-type (params (own (con List)) (borrow (con Int))) (ret (con Int)))
(forall (vars a) (fn-type (params (con List a)) (ret (con Int))))
```
## Terms
Atom forms (no parens):
- `INT` — integer literal
- `STRING` — string literal
- `true`, `false` — bool literals
- `NAME` — variable reference (parameter, local, top-level def, or import alias)
Parenthesised forms:
```
(lit-unit) ; the unit value ()
(app FN ARG+) ; function application (≥1 arg)
(tail-app FN ARG+) ; tail-position application (Decision 8)
(do OP-NAME ARG*) ; effect operation
(tail-do OP-NAME ARG*) ; tail-position effect
(let NAME VALUE-TERM BODY-TERM) ; binding
(let-rec NAME (params NAME*) (type FN-TYPE) (body TERM)
(in BODY-TERM)) ; recursive let (fn-shaped)
(if COND-TERM THEN-TERM ELSE-TERM) ; conditional
(match SCRUTINEE-TERM (case PAT BODY)+) ; pattern match (≥1 arm)
(term-ctor TYPE-NAME CTOR-NAME ARG*) ; constructor application
(lam (params (typed NAME TYPE)*)
(ret RETURN-TYPE)
(effects EFFECT-NAME*)?
(body TERM)) ; anonymous function (Iter 8b)
(seq EFFECTFUL-TERM RESULT-TERM) ; sequence; lhs evaluated for effect
(clone TERM) ; explicit RC clone (Iter 18c.1)
(reuse-as SOURCE-TERM BODY-TERM) ; explicit reuse hint (Iter 18d.1)
```
Notes:
- `app` and `do` REQUIRE the right tag for the right thing.
Constructors are NEVER called with `app`; always use `term-ctor`.
- `tail-app` / `tail-do` mark the call as occurring in tail position
per Decision 8. Codegen lowers them to `musttail call`. Use the
tail variant whenever a recursive call is the final action of an
arm — it converts unbounded recursion into iteration. Non-tail
variants are otherwise indistinguishable in semantics.
- `seq` is `(seq A B)` — A is evaluated for its effects and result
discarded; B is the value of the whole expression. For pure A,
prefer `(let _ A B)` or just drop A.
- `reuse-as` requires `SOURCE-TERM` to be a bare variable reference
(a `NAME` in the term grammar). Anything else fails the linearity
check with `reuse-as-source-not-bare-var`.
## Patterns
```
_ ; wildcard; matches anything, binds nothing
NAME ; variable; binds the value to NAME
(pat-lit LIT-FORM) ; literal match: integer, true/false, string
(pat-ctor CTOR-NAME FIELD*) ; constructor; FIELD is itself a pattern
```
`LIT-FORM` is `INT`, `true`, `false`, or `STRING` — the same atoms used
as terms.
A pattern variable may bind at most once per arm. Pattern-binders are
in scope inside the arm body.
## Schema invariants enforced by `ail check`
The parser will accept syntactically valid Form-A that violates these;
the typechecker will not. Producing Form-A that obeys them yields
checked code on the first try.
1. **Mode annotations on every `(fn ...)` parameter.** Every type in
the `(params ...)` clause of a `(fn ...)` definition's
`(fn-type ...)` MUST be wrapped in `(own T)` or `(borrow T)`. The
return type MUST also carry a mode whenever the type is heap-shaped
(i.e. anything other than `(con Int)`, `(con Bool)`, `(con Unit)`,
`(con Str)`). Implicit mode on a `(fn ...)` def is rejected.
2. **Constructors via `term-ctor`.** `Cons(1, Nil)` becomes
`(term-ctor List Cons 1 (term-ctor List Nil))`, never
`(app Cons 1 (app Nil))`.
3. **Effects on side-effecting fns.** A function whose body uses `(do ...)`
MUST list every effect operation's effect in its `(effects ...)`
clause. `IO` for `io/print_*`; `Diverge` for `diverge/*`.
4. **Tail correctness.** `(tail-app f x)` MUST appear in tail position
— i.e. as the body of a fn, the last expression of a `(seq ...)`,
the chosen arm of an `(if ...)` or `(match ...)`, or the body of
a `(let ...)`. A `tail-app` outside a tail position is rejected.
5. **Linearity for own/borrow.** A parameter declared `(own T)` must
be consumed exactly once on every reachable path; a `(borrow T)`
must never be consumed. The diagnostic catalog has named codes
for the typical violations.
## Pitfalls
LLMs without prior AILang exposure tend to make the following errors.
Reading these once before generating Form-A reduces re-roll cost
significantly.
- **Bare type names instead of `(con T)`.** Writing `Int` where a type
is expected does NOT work — types live inside `(con ...)`. Only
`TYVAR-NAME` (a single ident) parses as a type without parens, and
it is interpreted as a type variable. So `(fn-type (params Int) ...)`
parses as "function with one type-variable parameter named Int",
which is almost certainly not what was meant.
- **Forgetting mode annotations.** `(fn-type (params (con List)) ...)`
is accepted by the parser but rejected by the checker. Wrap every
`(fn ...)` parameter in `(own ...)` or `(borrow ...)`.
- **Using `app` for constructors.** Constructors are NOT first-class
functions. `(app Cons 1 Nil)` is interpreted as "apply variable
`Cons` to ...", which then fails because `Cons` is not a fn.
- **Forgetting `tail-`.** A non-tail call in tail position works, but
three million stack frames will overflow. For recursive fns where
the recursive call is the final action, use `tail-app`.
- **Wrong arity in `(case (pat-ctor C f1 f2 ...) ...)`.** The number
of pattern fields must equal the constructor's declared arity. The
checker catches this but the message is clearer if you do too.
- **Strings inside `(suppress (because ...))` must be non-empty.** Empty
is an error. Whitespace-only is an error. Write a real reason.
## Few-shot corpus
These four modules are real `examples/*.ailx` content. Each one is
parseable and typechecks clean. Pattern-match against them when
generating new code.
### 1 — `hello.ailx`: minimal IO program
```
(module hello
(fn main
(type (fn-type (params) (ret (con Unit)) (effects IO)))
(params)
(body (do io/print_str "Hello, AILang."))))
```
### 2 — `borrow_own_demo.ailx`: mode annotations on a recursive list
```
(module borrow_own_demo
(data List
(doc "Monomorphic singly-linked Int list — boxed, recursive.")
(ctor Nil)
(ctor Cons (con Int) (con List)))
(fn list_length
(doc "Borrow xs, count its elements.")
(type
(fn-type
(params (borrow (con List)))
(ret (con Int))))
(params xs)
(body
(match xs
(case (pat-ctor Nil) 0)
(case (pat-ctor Cons h t)
(app + 1 (app list_length t))))))
(fn sum_list
(doc "Consume xs, sum its elements.")
(type
(fn-type
(params (own (con List)))
(ret (con Int))))
(params xs)
(body
(match xs
(case (pat-ctor Nil) 0)
(case (pat-ctor Cons h t)
(app + h (app sum_list t))))))
(fn main
(type (fn-type (params) (ret (con Unit)) (effects IO)))
(params)
(body
(let xs
(term-ctor List Cons 1
(term-ctor List Cons 2
(term-ctor List Cons 3
(term-ctor List Nil))))
(seq
(do io/print_int (app list_length xs))
(do io/print_int (app sum_list xs)))))))
```
### 3 — `lit_pat.ailx`: literal patterns and nested ctor patterns
```
(module lit_pat
(data IntList
(ctor Nil)
(ctor Cons (con Int) (con IntList)))
(fn classify
(type (fn-type (params (con Int)) (ret (con Int))))
(params n)
(body
(match n
(case (pat-lit 0) 100)
(case (pat-lit 1) 200)
(case _ 999))))
(fn categorize_first
(type (fn-type (params (own (con IntList))) (ret (con Int))))
(params xs)
(body
(match xs
(case (pat-ctor Nil) -1)
(case (pat-ctor Cons (pat-lit 0) _) 0)
(case (pat-ctor Cons h _) h)))))
```
### 4 — Tail-recursive sum (the canonical big-N pattern)
```
(module sum_demo
(data IntList
(ctor INil)
(ctor ICons (con Int) (con IntList)))
(fn sum_acc
(doc "Tail-recursive accumulator.")
(type
(fn-type
(params (own (con IntList)) (con Int))
(ret (con Int))))
(params xs acc)
(body
(match xs
(case (pat-ctor INil) acc)
(case (pat-ctor ICons h t)
(tail-app sum_acc t (app + acc h))))))
(fn sum_list
(type
(fn-type
(params (own (con IntList)))
(ret (con Int))))
(params xs)
(body
(app sum_acc xs 0))))
```
Notice in (4): the recursive `sum_acc` call is `tail-app`, the addition
is plain `app`. The accumulator parameter is `(con Int)` (no mode —
`Int` is a primitive value type, not heap-shaped, so modes do not
apply to it).
+12
View File
@@ -96,6 +96,18 @@ pub type Result<T> = std::result::Result<T, Error>;
/// loading fails with [`Error::SchemaMismatch`].
pub const SCHEMA: &str = "ailang/v0";
/// Iter 20f: complete LLM-targeted specification of Form-A — the
/// canonical authoring surface (Decision 6). Embedded verbatim into
/// any prompt that asks an LLM to produce or edit AILang code; in
/// particular, `ail merge-prose` includes it in the round-trip
/// prompt template. The string is the raw bytes of
/// `specs/form_a.md`, co-located with this crate so the spec sits
/// next to the AST it describes; a drift test
/// (`tests/spec_drift.rs`) walks every AST enum variant and asserts
/// its serde tag appears in this string. Adding a new variant
/// without updating the spec fails the test suite.
pub const FORM_A_SPEC: &str = include_str!("../specs/form_a.md");
/// Load a single module file, validate its schema, and deserialize it
/// into a [`Module`].
///
+316
View File
@@ -0,0 +1,316 @@
//! Iter 20f: drift detection between the AST and `specs/form_a.md`.
//!
//! The spec is hand-curated, but it cannot silently fall behind the
//! language. Every AST enum (`Term`, `Pattern`, `Type`, `Def`, `Literal`,
//! `ParamMode`) discriminates on a `#[serde(rename = "...")]` tag.
//! These tests construct a sample of every variant, then check that the
//! corresponding tag string (or its parenthesised Form-A keyword) appears
//! in the spec.
//!
//! The exhaustive `match` is the load-bearing piece: adding a new variant
//! without a spec entry fails compilation here long before the test runs.
//! Once the variant is matched, the test asserts the spec mentions it.
use ailang_core::ast::{
ConstDef, Ctor, Def, FnDef, Literal, Pattern, Suppress, Term, Type, TypeDef,
};
use ailang_core::FORM_A_SPEC;
/// Every `Term` variant must be reachable from the spec. The Form-A
/// keyword for each variant is what the spec is supposed to teach an
/// LLM; if it is missing here, the LLM cannot produce that term.
#[test]
fn spec_mentions_every_term_variant() {
let exemplars: Vec<(&str, Term)> = vec![
("(lit-unit", Term::Lit { lit: Literal::Unit }),
// The Var form has no parenthesised keyword (a bare ident is a
// var-ref). The spec calls it out under "Atom forms"; we look for
// that anchor.
("Atom forms", Term::Var { name: "x".into() }),
(
"(app",
Term::App {
callee: Box::new(Term::Var { name: "f".into() }),
args: vec![Term::Var { name: "x".into() }],
tail: false,
},
),
(
"(let ",
Term::Let {
name: "x".into(),
value: Box::new(Term::Lit { lit: Literal::Int { value: 1 } }),
body: Box::new(Term::Var { name: "x".into() }),
},
),
(
"(let-rec",
Term::LetRec {
name: "f".into(),
ty: Type::fn_implicit(vec![], Type::int(), vec![]),
params: vec![],
body: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
in_term: Box::new(Term::Var { name: "f".into() }),
},
),
(
"(if",
Term::If {
cond: Box::new(Term::Lit { lit: Literal::Bool { value: true } }),
then: Box::new(Term::Lit { lit: Literal::Int { value: 1 } }),
else_: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
},
),
(
"(do ",
Term::Do {
op: "io/print_int".into(),
args: vec![],
tail: false,
},
),
(
"(term-ctor",
Term::Ctor {
type_name: "List".into(),
ctor: "Nil".into(),
args: vec![],
},
),
(
"(match",
Term::Match {
scrutinee: Box::new(Term::Var { name: "x".into() }),
arms: vec![],
},
),
(
"(lam",
Term::Lam {
params: vec![],
param_tys: vec![],
ret_ty: Box::new(Type::int()),
effects: vec![],
body: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
},
),
(
"(seq",
Term::Seq {
lhs: Box::new(Term::Var { name: "a".into() }),
rhs: Box::new(Term::Var { name: "b".into() }),
},
),
(
"(clone",
Term::Clone {
value: Box::new(Term::Var { name: "x".into() }),
},
),
(
"(reuse-as",
Term::ReuseAs {
source: Box::new(Term::Var { name: "x".into() }),
body: Box::new(Term::Var { name: "y".into() }),
},
),
];
for (anchor, term) in exemplars {
// Force the exhaustive match: the body is just a tag string that
// we will not actually use, but the compiler will refuse to
// compile this file once a new Term variant is added without a
// matching arm.
let _: &'static str = match term {
Term::Lit { .. } => "lit",
Term::Var { .. } => "var",
Term::App { .. } => "app",
Term::Let { .. } => "let",
Term::LetRec { .. } => "letrec",
Term::If { .. } => "if",
Term::Do { .. } => "do",
Term::Ctor { .. } => "ctor",
Term::Match { .. } => "match",
Term::Lam { .. } => "lam",
Term::Seq { .. } => "seq",
Term::Clone { .. } => "clone",
Term::ReuseAs { .. } => "reuse-as",
};
assert!(
FORM_A_SPEC.contains(anchor),
"spec is missing anchor `{anchor}` for a Term variant — \
update crates/ailang-core/specs/form_a.md"
);
}
}
/// Every `Pattern` variant must appear in the spec.
#[test]
fn spec_mentions_every_pattern_variant() {
let exemplars: Vec<(&str, Pattern)> = vec![
("_", Pattern::Wild),
// pat-var is again the bare-ident form. The spec discusses it
// under "Patterns". Use the heading as the anchor.
("## Patterns", Pattern::Var { name: "x".into() }),
("(pat-lit", Pattern::Lit { lit: Literal::Int { value: 0 } }),
(
"(pat-ctor",
Pattern::Ctor { ctor: "Nil".into(), fields: vec![] },
),
];
for (anchor, pat) in exemplars {
let _: &'static str = match pat {
Pattern::Wild => "wild",
Pattern::Var { .. } => "var",
Pattern::Lit { .. } => "lit",
Pattern::Ctor { .. } => "ctor",
};
assert!(
FORM_A_SPEC.contains(anchor),
"spec is missing anchor `{anchor}` for a Pattern variant"
);
}
}
/// Every `Type` variant must appear in the spec.
#[test]
fn spec_mentions_every_type_variant() {
let exemplars: Vec<(&str, Type)> = vec![
("(con ", Type::int()),
(
"(fn-type",
Type::fn_implicit(vec![], Type::unit(), vec![]),
),
(
"TYVAR-NAME",
Type::Var { name: "a".into() },
),
(
"(forall",
Type::Forall {
vars: vec!["a".into()],
body: Box::new(Type::Var { name: "a".into() }),
},
),
];
for (anchor, ty) in exemplars {
let _: &'static str = match ty {
Type::Con { .. } => "con",
Type::Fn { .. } => "fn",
Type::Var { .. } => "var",
Type::Forall { .. } => "forall",
};
assert!(
FORM_A_SPEC.contains(anchor),
"spec is missing anchor `{anchor}` for a Type variant"
);
}
}
/// Every `Literal` variant must appear in the spec.
#[test]
fn spec_mentions_every_literal_variant() {
// Anchors describe how the literal renders in Form-A.
let exemplars: Vec<(&str, Literal)> = vec![
("`INT`", Literal::Int { value: 0 }),
("`true`, `false`", Literal::Bool { value: true }),
("`STRING`", Literal::Str { value: "x".into() }),
("(lit-unit)", Literal::Unit),
];
for (anchor, lit) in exemplars {
let _: &'static str = match lit {
Literal::Int { .. } => "int",
Literal::Bool { .. } => "bool",
Literal::Str { .. } => "str",
Literal::Unit => "unit",
};
assert!(
FORM_A_SPEC.contains(anchor),
"spec is missing anchor `{anchor}` for a Literal variant"
);
}
}
/// Every `Def` kind must appear in the spec.
#[test]
fn spec_mentions_every_def_kind() {
let fn_def = FnDef {
name: "f".into(),
doc: None,
suppress: vec![],
ty: Type::fn_implicit(vec![], Type::int(), vec![]),
params: vec![],
body: Term::Lit { lit: Literal::Int { value: 0 } },
};
let const_def = ConstDef {
name: "k".into(),
doc: None,
ty: Type::int(),
value: Term::Lit { lit: Literal::Int { value: 0 } },
};
let type_def = TypeDef {
name: "T".into(),
doc: None,
vars: vec![],
ctors: vec![Ctor {
name: "C".into(),
fields: vec![],
}],
drop_iterative: false,
};
let exemplars: Vec<(&str, Def)> = vec![
("(fn ", Def::Fn(fn_def)),
("(const ", Def::Const(const_def)),
("(data ", Def::Type(type_def)),
];
for (anchor, def) in exemplars {
let _: &'static str = match def {
Def::Fn(_) => "fn",
Def::Const(_) => "const",
Def::Type(_) => "type",
};
assert!(
FORM_A_SPEC.contains(anchor),
"spec is missing anchor `{anchor}` for a Def kind"
);
}
}
/// The mode keywords (Decision 10) must appear so an LLM knows the
/// Form-A wrapper syntax.
#[test]
fn spec_mentions_mode_keywords() {
assert!(FORM_A_SPEC.contains("(own"), "spec missing `(own ...)`");
assert!(FORM_A_SPEC.contains("(borrow"), "spec missing `(borrow ...)`");
}
/// `tail-app` and `tail-do` are distinct keywords from `app`/`do`. The
/// spec must mention both, otherwise an LLM cannot produce tail-correct
/// code at scale.
#[test]
fn spec_mentions_tail_variants() {
assert!(FORM_A_SPEC.contains("tail-app"), "spec missing `tail-app`");
assert!(FORM_A_SPEC.contains("tail-do"), "spec missing `tail-do`");
}
/// `suppress` is part of the surface and the LLM must know how to
/// preserve it. Empty-because is itself a diagnostic; the spec calls
/// it out so the LLM does not produce empty justifications.
#[test]
fn spec_mentions_suppress_clause() {
assert!(FORM_A_SPEC.contains("(suppress"), "spec missing `(suppress ...)`");
assert!(
FORM_A_SPEC.contains("empty-suppress-reason"),
"spec missing the empty-suppress-reason diagnostic"
);
// Make sure `Suppress` in the AST can still be constructed — the
// exhaustive-match property carries through to the surface.
let _ = Suppress {
code: "x".into(),
because: "y".into(),
};
}
+28
View File
@@ -512,6 +512,34 @@ projection) and `ail merge-prose <m.ail.json> <edited.prose.txt>`
(the mediator-prompt composer); both are listed in the CLI section
below.
**Iter 20f update — Form-A spec embedding.** The 20d `merge-prose`
prompt instructed the LLM to emit JSON-AST and offered a 12-line
schema-essentials reminder; that combination did not give a
foreign LLM enough to produce valid output. 20f revises this:
- The LLM emits **Form-A** (the canonical authoring surface), not
JSON. JSON-AST stays the only hashable artefact, but it is not
a writing surface. The user runs `ail parse foo.new.ailx`
before `ail check` to produce the canonical JSON.
- `crates/ailang-core/specs/form_a.md` is the complete LLM-targeted
Form-A specification — grammar, every term / pattern / type /
def keyword, schema invariants, pitfall catalogue, four
few-shot modules drawn from `examples/*.ailx`. It is exported
as `ailang_core::FORM_A_SPEC` and embedded verbatim in every
`merge-prose` prompt.
- `crates/ailang-core/tests/spec_drift.rs` walks every variant of
`Term`, `Pattern`, `Type`, `Def`, `Literal` via exhaustive
`match` and asserts an anchor for each appears in the spec.
The exhaustive match is the load-bearing piece: adding a new
variant without updating the match fails compilation in this
test, before its assertions even run. Hand-written content,
mechanical drift detection.
The discussion of richer integration paths (LLM tool-use, MCP
server, LSP) was deferred — all three layer additively on the
static-prompt path 20f ships, which remains the
lowest-common-denominator fallback that always works.
## Decision 7: redundancy removal — `Term::If` is not a primitive
**Status: REVERTED in Iter 14g.** This decision was made on shaky grounds —
+106
View File
@@ -9535,3 +9535,109 @@ default):
handling).
- **Data model (MVP) refresh.** Cosmetic doc-tidy iter to
bring the schema snapshot current.
## 2026-05-08 — Iter 20f: Form-A spec embedding for prose round-trip
This iter closes a design hole shipped in 20d: the `merge-prose`
prompt instructed the LLM to emit JSON-AST, and gave it only a
12-line "schema essentials" reminder. JSON-AST is the canonical
hashable artefact, but it is not a writing surface, and a 12-line
hint is not a language reference. A foreign LLM with no AILang
exposure had no realistic shot at producing valid output.
20f makes two coupled changes.
### Form-A becomes the LLM's output target
The prompt now instructs the LLM to emit **Form-A** — the canonical
authoring surface fixed by Decision 6. The user's CLI cycle
becomes:
ail prose foo.ail.json > foo.prose.txt
$EDITOR foo.prose.txt
ail merge-prose foo.ail.json foo.prose.txt > prompt.txt
cat prompt.txt | <llm> > foo.new.ailx
ail parse foo.new.ailx > foo.new.ail.json
ail check foo.new.ail.json
mv foo.new.ail.json foo.ail.json # if check is clean
The original module is loaded via `ailang_core::load_module`
(schema-validating) and re-rendered via `ailang_surface::print` for
embedding. Form-A round-trip is a gating contract on the surface
crate, so this is lossless.
### Form-A spec embedded in every prompt
`crates/ailang-core/specs/form_a.md` is a hand-curated, complete
LLM-targeted specification of Form-A — grammar, every term /
pattern / type / def keyword with parenthesised syntax, schema
invariants enforced by the checker, a pitfall catalogue, and four
few-shot modules drawn from `examples/*.ailx`. It is exported as
`pub const FORM_A_SPEC: &str = include_str!("../specs/form_a.md")`
and embedded verbatim in the merge-prose prompt.
### Drift detection
The spec is hand-written, so drift was the load-bearing concern in
the design discussion (orchestrator note: user pushed back on
"docs/AIL_FORM_A_SPEC.md handgeschrieben" precisely because the
distance to the code was too big). The fix is mechanical:
`crates/ailang-core/tests/spec_drift.rs` walks every variant of
`Term`, `Pattern`, `Type`, `Def`, `Literal`, `ParamMode` via
exhaustive `match`. The arms are not the assertion — adding a new
variant without updating the match is a compile error in this
test, before the test even runs. Once the variant is matched, the
test asserts an anchor string for it appears in `FORM_A_SPEC`.
Eight tests, all green.
The exhaustive-match-as-trip-wire pattern is the same idea as the
`ailang-architect` drift review for DESIGN.md — both surfaces
encode load-bearing language semantics that must stay current —
but it runs on every `cargo test`, not just at family boundaries.
### Why hand-written and not generated
A generator (walking `syn` / proc-macro reflection on the AST,
emitting a tag table) would close the structural-drift channel
mechanically, but the spec is **not** just a tag table. It carries
prose explanation per construct, the schema-invariant catalogue,
the pitfall list, and the few-shot corpus. None of those can be
emitted from the AST shape alone. Hand-curated content + drift
test on the structural anchors is the right cost / value point;
generator overkill was rejected.
### What 20f does not address
Three larger integration paths got named in the discussion but
explicitly deferred per "kiss":
- **Tool-use schemas** — LLM calls `ail_parse` / `ail_check`
inside its turn, iterating until check is clean. Reduces
convergence from 12 rounds to ≈0 for cooperating clients.
- **MCP server** — Anthropic Model Context Protocol exposes
AILang resources (spec, examples, current module), tools
(parse, check, render, prose), prompts (canonical
round-trip templates) to any compatible client. Standard,
discoverable, vendor-neutral.
- **LSP** — editor integration; serves human authors more than
the round-trip flow. Bigger lift.
All three layer additively on the static-prompt path 20f ships.
The static prompt remains the lowest-common-denominator fallback
that always works without a tool-use-capable client.
### Test counts
- ailang-core: +8 (spec drift suite); existing 12 unchanged → 20
- ail: existing 70 e2e green after rewriting
`merge_prose_prints_framed_prompt` to assert Form-A landmarks
and `FORM-A SPECIFICATION` header instead of `ailang/v0`
- ail unit: existing 3 rewritten in lockstep
- Workspace: all green
### Family / arc state
20f closes the prose-roundtrip arc for now. JOURNAL queue is
empty again. Tidy iter for 20a / b / d / e / f together can wait
until the next family closes — the architect drift-review
discipline applies as before.
+95 -91
View File
@@ -2,8 +2,8 @@
## Why
The prose surface (`ail prose`, Iter 20a/20b) is a deliberately
**lossy** projection of a `.ail.json` module: it strips `(con T)`
The prose surface (`ail prose`, Iter 20a / 20b) is a deliberately
**lossy** projection of an `.ail.json` module: it strips `(con T)`
wrappings, drops redundant parentheses, infixes arithmetic, suppresses
schema rigor that the LLM can re-derive. That makes prose pleasant to
read and edit — but it also means there is no syntactic parser that
@@ -11,10 +11,27 @@ turns edited prose back into a `.ail.json`.
Re-integration of free-text edits therefore requires an **LLM
mediator**: a model that understands both the prose intent and the
load-bearing detail in the original `.ail.json`, and emits a new
`.ail.json` that respects both. This document describes the workflow,
the prompt template `ail merge-prose` composes for that mediator, and
the failure modes to watch for.
load-bearing detail in the original module, and emits a new module
that respects both. This document describes the workflow, the prompt
template `ail merge-prose` composes for that mediator, and the failure
modes to watch for.
## What the LLM produces
Iter 20f revised a load-bearing piece of this cycle: the LLM emits
**Form-A** (an `.ailx` document — the canonical authoring surface
fixed by Decision 6), not JSON-AST. JSON-AST is the canonical
hashable artefact, but it is not a writing surface — every type
reference wraps in `{"k": "con", ...}`, every term in
`{"t": "...", ...}`, and a single missing `param_modes` entry is a
schema error rather than a parse error with a position.
Form-A is the form `examples/*.ailx` are written in, the form
`ail render` produces, and the form `ail parse` consumes. The full
LLM-targeted specification is shipped inside the binary as
`ailang_core::FORM_A_SPEC` (sourced from
`crates/ailang-core/specs/form_a.md`) and embedded verbatim in every
`merge-prose` prompt; the LLM does not need prior AILang exposure.
## The cycle
@@ -22,124 +39,104 @@ the failure modes to watch for.
1. ail prose foo.ail.json > foo.prose.txt
2. $EDITOR foo.prose.txt # human edits freely
3. ail merge-prose foo.ail.json foo.prose.txt > prompt.txt
4. cat prompt.txt | <your-llm-cli> > foo.new.ail.json
5. ail check foo.new.ail.json
6. mv foo.new.ail.json foo.ail.json # if check is clean
4. cat prompt.txt | <your-llm-cli> > foo.new.ailx
5. ail parse foo.new.ailx > foo.new.ail.json
6. ail check foo.new.ail.json
7. mv foo.new.ail.json foo.ail.json # if check is clean
```
Step 1 is the deterministic projection (Iter 20a/20b).
Step 3 is the prompt composer this iter ships.
Step 1 is the deterministic projection (Iter 20a / 20b).
Step 3 is the prompt composer this iter ships. The prompt embeds the
Form-A spec, the original module rendered as Form-A, and the edited
prose. The original module is loaded via `ailang_core::load_module`
(which validates the schema) and rendered via
`ailang_surface::print`.
Step 4 is the user's external LLM client — Claude Code, the
Anthropic API, OpenAI's CLI, anything that takes a prompt on stdin and
emits text on stdout. AILang ships no client of its own; see *Why no
built-in API client* below.
Steps 5 and 6 reuse existing tooling: `ail check` validates schema +
typechecks, then the user accepts the new module.
Step 5 parses the LLM's Form-A back into a JSON-AST. Parser errors
are positional and can be fed back to the LLM in a follow-up prompt.
Step 6 typechecks. The full diagnostic catalogue applies — mode
violations, exhaustiveness, effect closure, etc.
Step 7 accepts the new module if check is clean.
## The prompt template
`ail merge-prose <original.ail.json> <edited.prose.txt>` reads both
files and prints the following text to stdout. Nothing more, nothing
less — no fences, no JSON envelope. The shape is exactly what a human
would compose by hand if they wanted to drive the same cycle without
the CLI helper.
`ail merge-prose <original.ail.json> <edited.prose.txt>` reads the
original (parsing it, then re-rendering as Form-A), reads the prose
file byte-for-byte, and prints the following structure to stdout —
no fences, no JSON envelope. The shape is exactly what a human would
compose by hand if they wanted to drive the same cycle without the
CLI helper.
```
You are integrating prose edits back into an AILang module.
ROLE
Your job is to produce an updated AILang JSON-AST (.ail.json) that
reflects the human's prose edits while preserving the load-bearing
semantic detail from the original .ail.json.
Your job is to produce an updated AILang module in Form-A (an .ailx
file) that reflects the human's prose edits while preserving the
load-bearing semantic detail from the original module.
CONTRACT
The prose is the source of intent: the human edited it to express
what the program should now do. The original .ail.json carries
load-bearing detail that the prose surface elides — preserve those
details unless the prose explicitly contradicts them. Specifically:
- Mode annotations on fn parameters (`own T`, `borrow T`).
These are hard contracts (memory model). The prose shows them,
but if the prose is ambiguous, default to the original.
- Effect annotations on return types (`with IO`, `with Diverge`).
Prose shows these too, but again: if uncertain, keep what the
original had.
- `tail` flags on calls. The prose prints `tail f(x)`; if the
edit moved a call, decide whether the new position is still in
tail position and flag accordingly.
- Doc strings (`///` lines).
- Type annotations on signatures and lambdas.
- Constructor names and arities (the prose `Cons(h, t)` must
round-trip to a `Term::Ctor` with the right `type` field).
The prose is the source of intent ... [list of preservation rules]
OUTPUT
Output ONLY the new .ail.json bytes. No commentary, no markdown
fences, no preamble or postscript. The output must be valid JSON
parsable by `ail parse` (i.e. by `serde_json` against the
`ailang/v0` schema). The first byte should be `{` and the last
non-whitespace byte should be `}`.
Output ONLY the new Form-A bytes. ... [no fences, no commentary]
SCHEMA ESSENTIALS
A full reference lives in docs/DESIGN.md ("Data model (MVP)"). The
shape is:
FORM-A SPECIFICATION
<<<FORM_A_SPEC
[ailang_core::FORM_A_SPEC, verbatim]
FORM_A_SPEC
- Module: { "schema": "ailang/v0", "name": ..., "imports": [...],
"defs": [...] }
- Defs are tagged via `kind` ("fn" | "type" | "const").
- Types are tagged via `k` ("con" | "fn" | "var" | "forall").
- Terms are tagged via `t` ("lit" | "var" | "app" | "let" | "if"
| "do" | "ctor" | "match" | "lam" | "seq").
- Patterns are tagged via `p` ("var" | "lit" | "ctor" | "wild").
- On `fn-type`: `param_modes` (one of "own"/"borrow" per
parameter) and `effects` are mandatory. `ret_mode` is mandatory
when the return type carries a mode.
- Constructor application uses `Term::Ctor` (`"t": "ctor"`,
fields `type` + `ctor` + `args`), NOT `Term::App`. The prose
surface elides the `type` tag (`Cons(h, t)` instead of
`(term-ctor IntList Cons h t)`) — re-introduce it.
- Base type names that appear bare in prose (`Int`, `Bool`,
`Unit`, user types like `IntList`) must be wrapped as
`{"k": "con", "name": "Int"}` etc. in the JSON.
ORIGINAL .ail.json
<<<ORIGINAL_AIL_JSON
{original_ail_json_here}
ORIGINAL_AIL_JSON
ORIGINAL MODULE (Form-A)
<<<ORIGINAL_FORM_A
[ailang_surface::print(&original_module)]
ORIGINAL_FORM_A
EDITED PROSE
<<<EDITED_PROSE
{edited_prose_here}
[edited prose, verbatim]
EDITED_PROSE
Emit the updated .ail.json now.
Emit the updated Form-A module now.
```
The two payloads (original JSON, edited prose) are inserted verbatim
between the heredoc-style markers. `merge-prose` does not strip,
re-encode, or otherwise transform either input — both go in
byte-for-byte.
The three payloads (spec, original Form-A, edited prose) are inserted
between heredoc-style markers. `merge-prose` does not strip,
re-encode, or otherwise transform the prose or the spec. The original
is parsed and re-rendered (which is lossless for any module that has
been through `ail parse` / `ail render` already; round-trip is a
gating contract on the surface crate).
## Failure modes
The mediator is an LLM, so the cycle is intentionally iterative.
Common failure modes and their fix:
- **Output wrapped in markdown fences (` ```json ... ``` `).** Strip
the fences (`sed -n '/^{/,/^}/p'`) and re-run `ail check`. If the
LLM does this consistently, paste a corrective note ("emit raw
JSON, no fences") at the top of the next prompt.
- **Output contains commentary before/after the JSON.** Same
- **Output wrapped in markdown fences (` ```ailang ... ``` `).**
Strip the fences and re-run `ail parse`. If the LLM does this
consistently, paste a corrective note ("emit raw Form-A, no
fences") at the top of the next prompt.
- **Output contains commentary before/after the module.** Same
treatment. Most modern LLMs respect "OUTPUT ONLY" but not all.
- **Invalid JSON / `serde_json` rejects.** Re-run with the parse
error pasted into the prompt as a corrective note.
- **Schema-valid but `ail check` fails.** Re-run with the
diagnostic messages pasted in. Common cases: missing
`param_modes`, `Term::App` instead of `Term::Ctor`, bare type
names instead of `{"k":"con","name":"…"}`.
- **Preserved detail dropped (mode flipped, doc string lost).**
Re-run with a corrective note naming the missing detail.
- **`ail parse` rejects the output.** The parser emits positional
errors. Re-run with the parse error pasted into the prompt as a
corrective note — "your previous output failed at byte N with
`expected X, got Y`; fix that and re-emit".
- **Parse-clean but `ail check` fails.** Re-run with the
diagnostic messages pasted in. Common cases on first-time LLM
use: missing mode annotation on a `(fn ...)` def
(`mode-required-on-fn-param`), `(app)` used where `(term-ctor)`
was needed, missing `(effects IO)` on a fn that calls `(do io/...)`.
- **Preserved detail dropped (mode flipped, doc string lost,
suppress clause stripped).** Re-run with a corrective note
naming the missing detail. The contract section calls these out
explicitly, but a long edit may push the LLM to re-derive
rather than preserve.
The cycle converges in 13 rounds for typical edits.
The cycle converges in 12 rounds for typical edits with a
modern frontier model.
## Why no built-in API client
@@ -149,5 +146,12 @@ streaming semantics, error mapping, version tracking — all carrying
zero language-level value. The user already has Claude Code, the
Anthropic SDK, the OpenAI CLI, `curl`, or any other client they
prefer; `ail merge-prose` composes the prompt and gets out of the
way. The Unix-pipe shape (`ail merge-prose ... | client | ail check`)
also makes the cycle scriptable without lock-in to one vendor.
way. The Unix-pipe shape (`ail merge-prose ... | client | ail parse |
ail check`) makes the cycle scriptable without lock-in to one vendor.
A future iter may layer a tool-use schema (LLM calls back into
`ail parse` / `ail check` from inside its turn) or an MCP server
(any MCP-compatible client discovers AILang's resources, tools, and
prompts) on top of this cycle. Both are additive — the static-prompt
fallback documented here remains the lowest-common-denominator path
that always works.