lex_types/
env.rs

1//! Type environment: type-decl info and value-binding scopes.
2
3use crate::types::*;
4use indexmap::IndexMap;
5
6#[derive(Debug, Clone)]
7pub struct TypeDef {
8    pub params: Vec<String>,
9    pub kind: TypeDefKind,
10}
11
12#[derive(Debug, Clone)]
13pub enum TypeDefKind {
14    /// A union: variant name → optional payload.
15    Union(IndexMap<String, Option<Ty>>),
16    /// A record alias: `type Foo = { x :: Int }` etc.
17    Alias(Ty),
18    /// Built-in opaque (Map, Set, ...).
19    Opaque,
20}
21
22#[derive(Debug, Clone, Default)]
23pub struct TypeEnv {
24    /// Type-name → definition.
25    pub types: IndexMap<String, TypeDef>,
26    /// Constructor name → owning type-name.
27    pub ctor_to_type: IndexMap<String, String>,
28}
29
30impl TypeEnv {
31    pub fn new_with_builtins() -> Self {
32        let mut e = TypeEnv::default();
33        // Result[T, E] = Ok(T) | Err(E)
34        let mut r_variants = IndexMap::new();
35        r_variants.insert("Ok".into(), Some(Ty::Var(0))); // T
36        r_variants.insert("Err".into(), Some(Ty::Var(1))); // E
37        e.types.insert("Result".into(), TypeDef {
38            params: vec!["T".into(), "E".into()],
39            kind: TypeDefKind::Union(r_variants),
40        });
41        e.ctor_to_type.insert("Ok".into(), "Result".into());
42        e.ctor_to_type.insert("Err".into(), "Result".into());
43
44        // Option[T] = Some(T) | None
45        let mut o_variants = IndexMap::new();
46        o_variants.insert("Some".into(), Some(Ty::Var(0))); // T
47        o_variants.insert("None".into(), None);
48        e.types.insert("Option".into(), TypeDef {
49            params: vec!["T".into()],
50            kind: TypeDefKind::Union(o_variants),
51        });
52        e.ctor_to_type.insert("Some".into(), "Option".into());
53        e.ctor_to_type.insert("None".into(), "Option".into());
54
55        // Nil = Unit (alias)
56        e.types.insert("Nil".into(), TypeDef {
57            params: vec![],
58            kind: TypeDefKind::Alias(Ty::Unit),
59        });
60
61        // Map, Set: opaque-ish. We just register the names so they parse as Cons.
62        e.types.insert("Map".into(), TypeDef { params: vec!["K".into(), "V".into()], kind: TypeDefKind::Opaque });
63        e.types.insert("Set".into(), TypeDef { params: vec!["T".into()], kind: TypeDefKind::Opaque });
64
65        // SqlParam = PStr(Str) | PInt(Int) | PFloat(Float) | PBool(Bool) | PNull
66        // Typed parameter binding for std.sql (#362). Replaces the v1 List[Str]
67        // approach so callers don't have to stringify non-string values.
68        let mut sp_variants = IndexMap::new();
69        sp_variants.insert("PStr".into(),   Some(Ty::str()));
70        sp_variants.insert("PInt".into(),   Some(Ty::int()));
71        sp_variants.insert("PFloat".into(), Some(Ty::float()));
72        sp_variants.insert("PBool".into(),  Some(Ty::bool()));
73        sp_variants.insert("PNull".into(),  None);
74        e.types.insert("SqlParam".into(), TypeDef {
75            params: vec![],
76            kind: TypeDefKind::Union(sp_variants),
77        });
78        for ctor in &["PStr", "PInt", "PFloat", "PBool", "PNull"] {
79            e.ctor_to_type.insert((*ctor).into(), "SqlParam".into());
80        }
81
82        // SqlTx: opaque transaction handle (#362). Backed by the same
83        // Int registry key as Db; the type system enforces that commit/
84        // rollback can only be called on a value from sql.begin, not on
85        // a raw Db connection.
86        e.types.insert("SqlTx".into(), TypeDef { params: vec![], kind: TypeDefKind::Opaque });
87
88        // SqlError = { message :: Str, code :: Option[Str], detail :: Option[Str] }
89        // Structured error shape returned by every `std.sql` op (#380).
90        // `code` carries the SQLSTATE (Postgres) or the symbolic SQLite
91        // error name (`SQLITE_BUSY`, `SQLITE_CONSTRAINT_UNIQUE`, …) so
92        // dialect-aware retry / conflict-handling can avoid string
93        // parsing. `message` is always populated; `detail` carries a
94        // driver-side detail string when present.
95        let mut se_fields = IndexMap::new();
96        se_fields.insert("message".into(), Ty::str());
97        se_fields.insert("code".into(), Ty::Con("Option".into(), vec![Ty::str()]));
98        se_fields.insert("detail".into(), Ty::Con("Option".into(), vec![Ty::str()]));
99        e.types.insert("SqlError".into(), TypeDef {
100            params: vec![],
101            kind: TypeDefKind::Alias(Ty::Record(se_fields)),
102        });
103
104        // AeadResult = { ciphertext :: Bytes, tag :: Bytes } — return
105        // shape for every AEAD seal op in `std.crypto` (#382 AEAD slice).
106        // The auth tag is split out from the ciphertext so callers don't
107        // have to know each algorithm's tag length: AES-GCM and
108        // ChaCha20-Poly1305 both happen to be 16 bytes today, but the
109        // shape keeps that detail encapsulated.
110        let mut ar_fields = IndexMap::new();
111        ar_fields.insert("ciphertext".into(), Ty::bytes());
112        ar_fields.insert("tag".into(), Ty::bytes());
113        e.types.insert("AeadResult".into(), TypeDef {
114            params: vec![],
115            kind: TypeDefKind::Alias(Ty::Record(ar_fields)),
116        });
117
118        // UdpDatagram = { data :: Bytes, host :: Str, port :: Int } —
119        // what `net.udp_recv` hands back (#760).
120        //
121        // The sender's address is part of the value rather than something
122        // the caller has to ask for separately, because with UDP it is not
123        // optional detail: any host can send to an open socket, so a reply
124        // that does not carry who sent it cannot be safely acted on. A
125        // request/response caller must check it matches who they asked.
126        let mut dg_fields = IndexMap::new();
127        dg_fields.insert("data".into(), Ty::bytes());
128        dg_fields.insert("host".into(), Ty::str());
129        dg_fields.insert("port".into(), Ty::int());
130        e.types.insert("UdpDatagram".into(), TypeDef {
131            params: vec![],
132            kind: TypeDefKind::Alias(Ty::Record(dg_fields)),
133        });
134
135        // Iter[T]: lazy positional iterator (#364). Backed at runtime by a
136        // (List[T], Int) tuple; the Int is the current cursor index. All
137        // iter.* operations are compiler-inlined so no effect is needed.
138        e.types.insert("Iter".into(), TypeDef { params: vec!["T".into()], kind: TypeDefKind::Opaque });
139
140        // Stream[T]: opaque streaming iterator (#305 slice 3).
141        // Built and consumed exclusively through the `stream.*` and
142        // `agent.cloud_stream` effect builtins; the runtime
143        // represents a Stream value as an opaque variant carrying a
144        // handle id. Registered as Opaque so type-checking knows
145        // `Stream[Str]` parses but doesn't unwrap it structurally.
146        e.types.insert("Stream".into(), TypeDef { params: vec!["T".into()], kind: TypeDefKind::Opaque });
147
148        // Tz = Utc | Local | Offset(Int) | Iana(Str).
149        // Used by std.datetime; the variant-typed alternative to the
150        // pre-v1 stringly Tz ("UTC" / "Local" / "+05:30" / IANA name).
151        // Registered globally so users don't have to import a module
152        // to mention `Utc` / `Iana("America/New_York")` etc.
153        let mut tz_variants = IndexMap::new();
154        tz_variants.insert("Utc".into(), None);
155        tz_variants.insert("Local".into(), None);
156        tz_variants.insert("Offset".into(), Some(Ty::int()));
157        tz_variants.insert("Iana".into(), Some(Ty::str()));
158        e.types.insert("Tz".into(), TypeDef {
159            params: vec![],
160            kind: TypeDefKind::Union(tz_variants),
161        });
162        for ctor in &["Utc", "Local", "Offset", "Iana"] {
163            e.ctor_to_type.insert((*ctor).into(), "Tz".into());
164        }
165
166        // HttpError = NetworkError(Str) | TimeoutError | TlsError(Str)
167        //           | DecodeError(Str)
168        // Used by std.http; structured failure shape so callers can
169        // discriminate transport vs. timeout vs. TLS vs. body-decode
170        // errors without parsing strings.
171        let mut http_err_variants = IndexMap::new();
172        http_err_variants.insert("NetworkError".into(), Some(Ty::str()));
173        http_err_variants.insert("TimeoutError".into(), None);
174        http_err_variants.insert("TlsError".into(), Some(Ty::str()));
175        http_err_variants.insert("DecodeError".into(), Some(Ty::str()));
176        e.types.insert("HttpError".into(), TypeDef {
177            params: vec![],
178            kind: TypeDefKind::Union(http_err_variants),
179        });
180        for ctor in &["NetworkError", "TimeoutError", "TlsError", "DecodeError"] {
181            e.ctor_to_type.insert((*ctor).into(), "HttpError".into());
182        }
183
184        // Json = JNull | JBool(Bool) | JInt(Int) | JFloat(Float)
185        //      | JStr(Str) | JList(List[Json]) | JObj(List[(Str, Json)])
186        // The generic JSON value ADT produced by `std.json.decode` and
187        // consumed by `std.json.encode`. Structurally identical to
188        // lex-schema's `json_value.Json`, so the native builtins are a
189        // drop-in for that interpreted parser. Registered globally (like
190        // Tz/HttpError) so a program can pattern-match `Json` without an
191        // extra type import. Recursive payloads reference the type by
192        // name via `Ty::Con("Json", [])`.
193        let json_ty = || Ty::Con("Json".into(), vec![]);
194        let mut json_variants = IndexMap::new();
195        json_variants.insert("JNull".into(), None);
196        json_variants.insert("JBool".into(), Some(Ty::bool()));
197        json_variants.insert("JInt".into(), Some(Ty::int()));
198        json_variants.insert("JFloat".into(), Some(Ty::float()));
199        json_variants.insert("JStr".into(), Some(Ty::str()));
200        json_variants.insert("JList".into(), Some(Ty::List(Box::new(json_ty()))));
201        json_variants.insert(
202            "JObj".into(),
203            Some(Ty::List(Box::new(Ty::Tuple(vec![Ty::str(), json_ty()])))),
204        );
205        e.types.insert("Json".into(), TypeDef {
206            params: vec![],
207            kind: TypeDefKind::Union(json_variants),
208        });
209        for ctor in &["JNull", "JBool", "JInt", "JFloat", "JStr", "JList", "JObj"] {
210            e.ctor_to_type.insert((*ctor).into(), "Json".into());
211        }
212
213        // HttpRequest = { method, url, headers, body, timeout_ms }.
214        // The std.http request shape. Anonymous record literals coerce
215        // to this nominal alias at every position (per the §3.13
216        // record-coercion rules), so users write
217        // `{ method: "GET", url: u, headers: map.new(), body: None,
218        // timeout_ms: None }` rather than a dedicated constructor —
219        // builders (`http.with_header` etc.) are pure transforms over
220        // the same shape.
221        let mut req_fields = IndexMap::new();
222        req_fields.insert("method".into(), Ty::str());
223        req_fields.insert("url".into(), Ty::str());
224        req_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
225        req_fields.insert("body".into(), Ty::Con("Option".into(), vec![Ty::bytes()]));
226        req_fields.insert("timeout_ms".into(), Ty::Con("Option".into(), vec![Ty::int()]));
227        e.types.insert("HttpRequest".into(), TypeDef {
228            params: vec![],
229            kind: TypeDefKind::Alias(Ty::Record(req_fields)),
230        });
231
232        // HttpResponse = { status, headers, body }. Returned by every
233        // `http.{send,get,post}` happy path; also the input to
234        // `http.{json_body,text_body}`.
235        let mut resp_fields = IndexMap::new();
236        resp_fields.insert("status".into(), Ty::int());
237        resp_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
238        resp_fields.insert("body".into(), Ty::bytes());
239        e.types.insert("HttpResponse".into(), TypeDef {
240            params: vec![],
241            kind: TypeDefKind::Alias(Ty::Record(resp_fields)),
242        });
243
244        // Matrix = { rows :: Int, cols :: Int, data :: List[Float] }.
245        // Used by std.math; runtime values are the F64Array fast lane,
246        // not a real record. The alias makes math.* signatures readable
247        // (`:: Matrix` instead of an inline record) and lets call sites
248        // unify nominally. Field access via `m.rows` would type-check
249        // but fail at runtime — use `math.rows / math.cols / math.get`.
250        let mut mat_fields = IndexMap::new();
251        mat_fields.insert("rows".into(), Ty::int());
252        mat_fields.insert("cols".into(), Ty::int());
253        mat_fields.insert("data".into(), Ty::List(Box::new(Ty::float())));
254        e.types.insert("Matrix".into(), TypeDef {
255            params: vec![],
256            kind: TypeDefKind::Alias(Ty::Record(mat_fields)),
257        });
258
259        // Request = { method :: Str, path :: Str, query :: Str, body :: Str,
260        //             headers :: Map[Str, Str], path_params :: Map[Str, Str] }
261        // Inbound request shape used by net.serve_fn handlers.
262        // `path_params` is populated by `net.serve_routed` from `:name`
263        // segments in the route pattern; empty under `net.serve_fn`.
264        let mut net_req_fields = IndexMap::new();
265        net_req_fields.insert("method".into(), Ty::str());
266        net_req_fields.insert("path".into(), Ty::str());
267        net_req_fields.insert("query".into(), Ty::str());
268        net_req_fields.insert("body".into(), Ty::str());
269        net_req_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
270        net_req_fields.insert("path_params".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
271        e.types.insert("Request".into(), TypeDef {
272            params: vec![],
273            kind: TypeDefKind::Alias(Ty::Record(net_req_fields)),
274        });
275
276        // Response = { status :: Int, body :: ResponseBody, headers :: Map[Str, Str] }
277        // Outbound response shape returned by net.serve_fn handlers.
278        // #375: `body` is now an ADT instead of a bare Str. Streaming
279        // variants (BodyStream / BodyBytes) carry an `Iter[T]` that the
280        // server drains chunk-by-chunk under chunked transfer-encoding.
281        let mut rb_variants = IndexMap::new();
282        rb_variants.insert("BodyStr".into(),    Some(Ty::str()));
283        rb_variants.insert(
284            "BodyStream".into(),
285            Some(Ty::Con("Iter".into(), vec![Ty::str()])),
286        );
287        rb_variants.insert(
288            "BodyBytes".into(),
289            Some(Ty::Con("Iter".into(), vec![Ty::List(Box::new(Ty::int()))])),
290        );
291        e.types.insert("ResponseBody".into(), TypeDef {
292            params: vec![],
293            kind: TypeDefKind::Union(rb_variants),
294        });
295        for ctor in &["BodyStr", "BodyStream", "BodyBytes"] {
296            e.ctor_to_type.insert((*ctor).into(), "ResponseBody".into());
297        }
298
299        let mut net_resp_fields = IndexMap::new();
300        net_resp_fields.insert("status".into(), Ty::int());
301        net_resp_fields.insert("body".into(), Ty::Con("ResponseBody".into(), vec![]));
302        net_resp_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
303        e.types.insert("Response".into(), TypeDef {
304            params: vec![],
305            kind: TypeDefKind::Alias(Ty::Record(net_resp_fields)),
306        });
307
308        // WsConn = { id :: Str, path :: Str, subprotocol :: Str }
309        // Passed to every net.serve_ws_fn message handler.
310        let mut ws_conn_fields = IndexMap::new();
311        ws_conn_fields.insert("id".into(), Ty::str());
312        ws_conn_fields.insert("path".into(), Ty::str());
313        ws_conn_fields.insert("subprotocol".into(), Ty::str());
314        e.types.insert("WsConn".into(), TypeDef {
315            params: vec![],
316            kind: TypeDefKind::Alias(Ty::Record(ws_conn_fields)),
317        });
318
319        // WsMessage = WsText(Str) | WsBinary(List[Int]) | WsPing | WsClose
320        let mut ws_msg_variants = IndexMap::new();
321        ws_msg_variants.insert("WsText".into(), Some(Ty::str()));
322        ws_msg_variants.insert("WsBinary".into(), Some(Ty::List(Box::new(Ty::int()))));
323        ws_msg_variants.insert("WsPing".into(), None);
324        ws_msg_variants.insert("WsClose".into(), None);
325        e.types.insert("WsMessage".into(), TypeDef {
326            params: vec![],
327            kind: TypeDefKind::Union(ws_msg_variants),
328        });
329        for ctor in &["WsText", "WsBinary", "WsPing", "WsClose"] {
330            e.ctor_to_type.insert((*ctor).into(), "WsMessage".into());
331        }
332
333        // WsAction = WsSend(Str) | WsSendBinary(List[Int]) | WsNoOp
334        // Handlers return this to tell the runtime what to send back.
335        // Connection close is handled automatically when the runtime receives
336        // an incoming WsClose frame; handlers do not need to emit a close action.
337        let mut ws_act_variants = IndexMap::new();
338        ws_act_variants.insert("WsSend".into(), Some(Ty::str()));
339        ws_act_variants.insert("WsSendBinary".into(), Some(Ty::List(Box::new(Ty::int()))));
340        ws_act_variants.insert("WsNoOp".into(), None);
341        e.types.insert("WsAction".into(), TypeDef {
342            params: vec![],
343            kind: TypeDefKind::Union(ws_act_variants),
344        });
345        for ctor in &["WsSend", "WsSendBinary", "WsNoOp"] {
346            e.ctor_to_type.insert((*ctor).into(), "WsAction".into());
347        }
348
349        // ConcError = AlreadyRegistered(Str) | NotRegistered(Str)
350        // Returned by `conc.register` / `conc.unregister` (#444). A
351        // third `TypeMismatch` variant is reserved for when the
352        // SigId-tagged registry lands — see `conc_registry.rs` in
353        // lex-bytecode for the deferred-design note.
354        let mut ce_variants = IndexMap::new();
355        ce_variants.insert("AlreadyRegistered".into(), Some(Ty::str()));
356        ce_variants.insert("NotRegistered".into(), Some(Ty::str()));
357        e.types.insert("ConcError".into(), TypeDef {
358            params: vec![],
359            kind: TypeDefKind::Union(ce_variants),
360        });
361        for ctor in &["AlreadyRegistered", "NotRegistered"] {
362            e.ctor_to_type.insert((*ctor).into(), "ConcError".into());
363        }
364
365        // ConnRedis: opaque handle for std.redis connections (#533).
366        // Backed at runtime by an Int into a process-wide registry,
367        // same pattern as Db (std.sql) and Kv (std.kv).
368        e.types.insert("ConnRedis".into(), TypeDef { params: vec![], kind: TypeDefKind::Opaque });
369
370        e
371    }
372
373    pub fn add_user_type(&mut self, name: &str, decl: lex_ast::TypeDecl) -> Result<(), String> {
374        match &decl.definition {
375            lex_ast::TypeExpr::Union { variants } => {
376                let mut vmap = IndexMap::new();
377                for v in variants {
378                    let payload = v.payload.as_ref().map(|p| ty_from_canon(p, &decl.params));
379                    vmap.insert(v.name.clone(), payload);
380                    self.ctor_to_type.insert(v.name.clone(), name.to_string());
381                }
382                self.types.insert(name.to_string(), TypeDef {
383                    params: decl.params.clone(),
384                    kind: TypeDefKind::Union(vmap),
385                });
386            }
387            other => {
388                let ty = ty_from_canon_env(other, &decl.params, self);
389                self.types.insert(name.to_string(), TypeDef {
390                    params: decl.params.clone(),
391                    kind: TypeDefKind::Alias(ty),
392                });
393            }
394        }
395        Ok(())
396    }
397}
398
399/// Convert canonical TypeExpr to internal Ty, treating type params as
400/// fresh-numbered Vars (0..n in declaration order). When instantiating, we
401/// substitute these out.
402pub fn ty_from_canon(t: &lex_ast::TypeExpr, params: &[String]) -> Ty {
403    match t {
404        lex_ast::TypeExpr::Named { name, args } => {
405            // type param?
406            if let Some(idx) = params.iter().position(|p| p == name) {
407                if !args.is_empty() {
408                    // Type params don't take args.
409                    return Ty::Con(name.clone(), args.iter().map(|a| ty_from_canon(a, params)).collect());
410                }
411                return Ty::Var(idx as u32);
412            }
413            // Primitives.
414            match name.as_str() {
415                "Int" => return Ty::int(),
416                "Float" => return Ty::float(),
417                "Bool" => return Ty::bool(),
418                "Str" => return Ty::str(),
419                "Bytes" => return Ty::bytes(),
420                "Unit" | "Nil" => return Ty::Unit,
421                "Never" => return Ty::Never,
422                "List" if args.len() == 1 => return Ty::List(Box::new(ty_from_canon(&args[0], params))),
423                // `Tuple[T0, T1, ...]` is the constructor surface for
424                // tuples; canonicalize to the structural Ty::Tuple so
425                // it unifies with `(T0, T1)` literal-tuple syntax and
426                // with std.tuple's signatures.
427                "Tuple" => return Ty::Tuple(args.iter().map(|a| ty_from_canon(a, params)).collect()),
428                _ => {}
429            }
430            Ty::Con(name.clone(), args.iter().map(|a| ty_from_canon(a, params)).collect())
431        }
432        lex_ast::TypeExpr::Record { fields } => {
433            let mut m = IndexMap::new();
434            for f in fields { m.insert(f.name.clone(), ty_from_canon(&f.ty, params)); }
435            Ty::Record(m)
436        }
437        lex_ast::TypeExpr::Tuple { items } => Ty::Tuple(items.iter().map(|t| ty_from_canon(t, params)).collect()),
438        lex_ast::TypeExpr::Function { params: ps, effects, effect_row_var, ret } => {
439            // Plumb effect args (#207).
440            let effs = EffectSet {
441                concrete: {
442                    let mut s = std::collections::BTreeSet::new();
443                    for e in effects {
444                        let arg = e.arg.as_ref().map(|a| match a {
445                            lex_ast::EffectArg::Str { value } => crate::types::EffectArg::Str(value.clone()),
446                            lex_ast::EffectArg::Int { value } => crate::types::EffectArg::Int(*value),
447                            lex_ast::EffectArg::Ident { value } => crate::types::EffectArg::Ident(value.clone()),
448                        });
449                        s.insert(crate::types::EffectKind { name: e.name.clone(), arg });
450                    }
451                    s
452                },
453                // Open-row tail: `[io | E]` where `E` is one of the enclosing
454                // type/fn's `params`. Resolve it to that param's index — the
455                // same id space as `Ty::Var(idx)`, but read back through the
456                // separate effect-substitution map at instantiation, so a
457                // type param and an effect-row param never collide.
458                var: effect_row_var
459                    .as_ref()
460                    .and_then(|name| params.iter().position(|p| p == name))
461                    .map(|i| i as u32),
462            };
463            Ty::Function {
464                params: ps.iter().map(|t| ty_from_canon(t, params)).collect(),
465                effects: effs,
466                ret: Box::new(ty_from_canon(ret, params)),
467            }
468        }
469        lex_ast::TypeExpr::Union { .. } => {
470            // Unions on the RHS of type-decls; not in arbitrary positions.
471            Ty::Unit
472        }
473        lex_ast::TypeExpr::Refined { base, .. } => {
474            // #209 slice 1: refinement types unify structurally as
475            // their base type. The predicate is parsed and stored in
476            // the AST (so `lex-vcs` content-addressing picks up
477            // refinement edits), but static discharge and runtime
478            // residual checks land in slices 2 and 3 of #209. The
479            // unification behavior here means a function declaring
480            // `Int{x | x > 0}` interoperates with plain `Int` callers
481            // — the predicate is informational until discharge is
482            // wired up.
483            ty_from_canon(base, params)
484        }
485        lex_ast::TypeExpr::RecordWithSpreads { .. } => {
486            // Caller should use ty_from_canon_env for spread resolution.
487            Ty::Unit
488        }
489    }
490}
491
492/// Like `ty_from_canon` but resolves `RecordWithSpreads` by looking up base
493/// type names in `env`. Called from `add_user_type` and `function_scheme` so
494/// that `{ ...Post, extra :: Int }` expands to a flat `Ty::Record`.
495pub fn ty_from_canon_env(t: &lex_ast::TypeExpr, params: &[String], env: &TypeEnv) -> Ty {
496    match t {
497        lex_ast::TypeExpr::RecordWithSpreads { spreads, fields } => {
498            let mut m = IndexMap::new();
499            for spread_name in spreads {
500                if let Some(td) = env.types.get(spread_name.as_str()) {
501                    if let TypeDefKind::Alias(Ty::Record(spread_fields)) = &td.kind {
502                        for (k, v) in spread_fields {
503                            m.insert(k.clone(), v.clone());
504                        }
505                    }
506                }
507            }
508            for f in fields {
509                m.insert(f.name.clone(), ty_from_canon_env(&f.ty, params, env));
510            }
511            Ty::Record(m)
512        }
513        other => ty_from_canon(other, params),
514    }
515}
lex_types/env.rs

lex_types/
env.rs
