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//! Type environment: type-decl info and value-binding scopes.
use crate::types::*;
use indexmap::IndexMap;
#[derive(Debug, Clone)]
pub struct TypeDef {
pub params: Vec<String>,
pub kind: TypeDefKind,
}
#[derive(Debug, Clone)]
pub enum TypeDefKind {
/// A union: variant name → optional payload.
Union(IndexMap<String, Option<Ty>>),
/// A record alias: `type Foo = { x :: Int }` etc.
Alias(Ty),
/// Built-in opaque (Map, Set, ...).
Opaque,
}
#[derive(Debug, Clone, Default)]
pub struct TypeEnv {
/// Type-name → definition.
pub types: IndexMap<String, TypeDef>,
/// Constructor name → owning type-name.
pub ctor_to_type: IndexMap<String, String>,
}
impl TypeEnv {
pub fn new_with_builtins() -> Self {
let mut e = TypeEnv::default();
// Result[T, E] = Ok(T) | Err(E)
let mut r_variants = IndexMap::new();
r_variants.insert("Ok".into(), Some(Ty::Var(0))); // T
r_variants.insert("Err".into(), Some(Ty::Var(1))); // E
e.types.insert("Result".into(), TypeDef {
params: vec!["T".into(), "E".into()],
kind: TypeDefKind::Union(r_variants),
});
e.ctor_to_type.insert("Ok".into(), "Result".into());
e.ctor_to_type.insert("Err".into(), "Result".into());
// Option[T] = Some(T) | None
let mut o_variants = IndexMap::new();
o_variants.insert("Some".into(), Some(Ty::Var(0))); // T
o_variants.insert("None".into(), None);
e.types.insert("Option".into(), TypeDef {
params: vec!["T".into()],
kind: TypeDefKind::Union(o_variants),
});
e.ctor_to_type.insert("Some".into(), "Option".into());
e.ctor_to_type.insert("None".into(), "Option".into());
// Nil = Unit (alias)
e.types.insert("Nil".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Alias(Ty::Unit),
});
// Map, Set: opaque-ish. We just register the names so they parse as Cons.
e.types.insert("Map".into(), TypeDef { params: vec!["K".into(), "V".into()], kind: TypeDefKind::Opaque });
e.types.insert("Set".into(), TypeDef { params: vec!["T".into()], kind: TypeDefKind::Opaque });
// Tz = Utc | Local | Offset(Int) | Iana(Str).
// Used by std.datetime; the variant-typed alternative to the
// pre-v1 stringly Tz ("UTC" / "Local" / "+05:30" / IANA name).
// Registered globally so users don't have to import a module
// to mention `Utc` / `Iana("America/New_York")` etc.
let mut tz_variants = IndexMap::new();
tz_variants.insert("Utc".into(), None);
tz_variants.insert("Local".into(), None);
tz_variants.insert("Offset".into(), Some(Ty::int()));
tz_variants.insert("Iana".into(), Some(Ty::str()));
e.types.insert("Tz".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Union(tz_variants),
});
for ctor in &["Utc", "Local", "Offset", "Iana"] {
e.ctor_to_type.insert((*ctor).into(), "Tz".into());
}
// HttpError = NetworkError(Str) | TimeoutError | TlsError(Str)
// | DecodeError(Str)
// Used by std.http; structured failure shape so callers can
// discriminate transport vs. timeout vs. TLS vs. body-decode
// errors without parsing strings.
let mut http_err_variants = IndexMap::new();
http_err_variants.insert("NetworkError".into(), Some(Ty::str()));
http_err_variants.insert("TimeoutError".into(), None);
http_err_variants.insert("TlsError".into(), Some(Ty::str()));
http_err_variants.insert("DecodeError".into(), Some(Ty::str()));
e.types.insert("HttpError".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Union(http_err_variants),
});
for ctor in &["NetworkError", "TimeoutError", "TlsError", "DecodeError"] {
e.ctor_to_type.insert((*ctor).into(), "HttpError".into());
}
// HttpRequest = { method, url, headers, body, timeout_ms }.
// The std.http request shape. Anonymous record literals coerce
// to this nominal alias at every position (per the §3.13
// record-coercion rules), so users write
// `{ method: "GET", url: u, headers: map.new(), body: None,
// timeout_ms: None }` rather than a dedicated constructor —
// builders (`http.with_header` etc.) are pure transforms over
// the same shape.
let mut req_fields = IndexMap::new();
req_fields.insert("method".into(), Ty::str());
req_fields.insert("url".into(), Ty::str());
req_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
req_fields.insert("body".into(), Ty::Con("Option".into(), vec![Ty::bytes()]));
req_fields.insert("timeout_ms".into(), Ty::Con("Option".into(), vec![Ty::int()]));
e.types.insert("HttpRequest".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Alias(Ty::Record(req_fields)),
});
// HttpResponse = { status, headers, body }. Returned by every
// `http.{send,get,post}` happy path; also the input to
// `http.{json_body,text_body}`.
let mut resp_fields = IndexMap::new();
resp_fields.insert("status".into(), Ty::int());
resp_fields.insert("headers".into(), Ty::Con("Map".into(), vec![Ty::str(), Ty::str()]));
resp_fields.insert("body".into(), Ty::bytes());
e.types.insert("HttpResponse".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Alias(Ty::Record(resp_fields)),
});
// Matrix = { rows :: Int, cols :: Int, data :: List[Float] }.
// Used by std.math; runtime values are the F64Array fast lane,
// not a real record. The alias makes math.* signatures readable
// (`:: Matrix` instead of an inline record) and lets call sites
// unify nominally. Field access via `m.rows` would type-check
// but fail at runtime — use `math.rows / math.cols / math.get`.
let mut mat_fields = IndexMap::new();
mat_fields.insert("rows".into(), Ty::int());
mat_fields.insert("cols".into(), Ty::int());
mat_fields.insert("data".into(), Ty::List(Box::new(Ty::float())));
e.types.insert("Matrix".into(), TypeDef {
params: vec![],
kind: TypeDefKind::Alias(Ty::Record(mat_fields)),
});
e
}
pub fn add_user_type(&mut self, name: &str, decl: lex_ast::TypeDecl) -> Result<(), String> {
match &decl.definition {
lex_ast::TypeExpr::Union { variants } => {
let mut vmap = IndexMap::new();
for v in variants {
let payload = v.payload.as_ref().map(|p| ty_from_canon(p, &decl.params));
vmap.insert(v.name.clone(), payload);
self.ctor_to_type.insert(v.name.clone(), name.to_string());
}
self.types.insert(name.to_string(), TypeDef {
params: decl.params.clone(),
kind: TypeDefKind::Union(vmap),
});
}
other => {
let ty = ty_from_canon(other, &decl.params);
self.types.insert(name.to_string(), TypeDef {
params: decl.params.clone(),
kind: TypeDefKind::Alias(ty),
});
}
}
Ok(())
}
}
/// Convert canonical TypeExpr to internal Ty, treating type params as
/// fresh-numbered Vars (0..n in declaration order). When instantiating, we
/// substitute these out.
pub fn ty_from_canon(t: &lex_ast::TypeExpr, params: &[String]) -> Ty {
match t {
lex_ast::TypeExpr::Named { name, args } => {
// type param?
if let Some(idx) = params.iter().position(|p| p == name) {
if !args.is_empty() {
// Type params don't take args.
return Ty::Con(name.clone(), args.iter().map(|a| ty_from_canon(a, params)).collect());
}
return Ty::Var(idx as u32);
}
// Primitives.
match name.as_str() {
"Int" => return Ty::int(),
"Float" => return Ty::float(),
"Bool" => return Ty::bool(),
"Str" => return Ty::str(),
"Bytes" => return Ty::bytes(),
"Unit" | "Nil" => return Ty::Unit,
"Never" => return Ty::Never,
"List" if args.len() == 1 => return Ty::List(Box::new(ty_from_canon(&args[0], params))),
// `Tuple[T0, T1, ...]` is the constructor surface for
// tuples; canonicalize to the structural Ty::Tuple so
// it unifies with `(T0, T1)` literal-tuple syntax and
// with std.tuple's signatures.
"Tuple" => return Ty::Tuple(args.iter().map(|a| ty_from_canon(a, params)).collect()),
_ => {}
}
Ty::Con(name.clone(), args.iter().map(|a| ty_from_canon(a, params)).collect())
}
lex_ast::TypeExpr::Record { fields } => {
let mut m = IndexMap::new();
for f in fields { m.insert(f.name.clone(), ty_from_canon(&f.ty, params)); }
Ty::Record(m)
}
lex_ast::TypeExpr::Tuple { items } => Ty::Tuple(items.iter().map(|t| ty_from_canon(t, params)).collect()),
lex_ast::TypeExpr::Function { params: ps, effects, ret } => {
// Plumb effect args (#207).
let effs = EffectSet {
concrete: {
let mut s = std::collections::BTreeSet::new();
for e in effects {
let arg = e.arg.as_ref().map(|a| match a {
lex_ast::EffectArg::Str { value } => crate::types::EffectArg::Str(value.clone()),
lex_ast::EffectArg::Int { value } => crate::types::EffectArg::Int(*value),
lex_ast::EffectArg::Ident { value } => crate::types::EffectArg::Ident(value.clone()),
});
s.insert(crate::types::EffectKind { name: e.name.clone(), arg });
}
s
},
var: None,
};
Ty::Function {
params: ps.iter().map(|t| ty_from_canon(t, params)).collect(),
effects: effs,
ret: Box::new(ty_from_canon(ret, params)),
}
}
lex_ast::TypeExpr::Union { .. } => {
// Unions on the RHS of type-decls; not in arbitrary positions.
Ty::Unit
}
lex_ast::TypeExpr::Refined { base, .. } => {
// #209 slice 1: refinement types unify structurally as
// their base type. The predicate is parsed and stored in
// the AST (so `lex-vcs` content-addressing picks up
// refinement edits), but static discharge and runtime
// residual checks land in slices 2 and 3 of #209. The
// unification behavior here means a function declaring
// `Int{x | x > 0}` interoperates with plain `Int` callers
// — the predicate is informational until discharge is
// wired up.
ty_from_canon(base, params)
}
}
}