Macro system done in theory

too afraid to begin debugging, resting for a moment

orchid-std/src/macros/mactree.rs

@@ -4,10 +4,11 @@ use std::rc::Rc;
 
 use futures::FutureExt;
 use futures::future::join_all;
+use hashbrown::HashSet;
 use itertools::Itertools;
 use orchid_api::Paren;
-use orchid_base::error::OrcErrv;
-use orchid_base::format::{FmtCtx, FmtUnit, Format, Variants};
+use orchid_base::error::{OrcErrv, Reporter, mk_errv};
+use orchid_base::format::{FmtCtx, FmtUnit, Format, Variants, fmt};
 use orchid_base::interner::Tok;
 use orchid_base::location::Pos;
 use orchid_base::name::Sym;
@@ -15,16 +16,71 @@ use orchid_base::tl_cache;
 use orchid_base::tree::indent;
 use orchid_extension::atom::Atomic;
 use orchid_extension::atom_owned::{OwnedAtom, OwnedVariant};
+use orchid_extension::conv::ToExpr;
 use orchid_extension::expr::Expr;
+use orchid_extension::gen_expr::{GExpr, arg, bot, call, lambda, sym_ref};
+use orchid_extension::system::SysCtx;
+use substack::Substack;
+
+#[derive(Clone)]
+pub struct LowerCtx<'a> {
+	pub sys: SysCtx,
+	pub rep: &'a Reporter,
+}
 
 #[derive(Debug, Clone)]
 pub struct MacTree {
 	pub pos: Pos,
 	pub tok: Rc<MacTok>,
+	pub glossary: Rc<HashSet<Sym>>,
 }
 impl MacTree {
-	pub fn tok(&self) -> &MacTok { &*self.tok }
+	pub fn tok(&self) -> &MacTok { &self.tok }
 	pub fn pos(&self) -> Pos { self.pos.clone() }
+	pub fn glossary(&self) -> &HashSet<Sym> { &self.glossary }
+	pub async fn lower(&self, ctx: LowerCtx<'_>, args: Substack<'_, Sym>) -> GExpr {
+		let expr = match self.tok() {
+			MacTok::Bottom(e) => bot(e.clone()),
+			MacTok::Lambda(arg, body) => {
+				let MacTok::Name(name) = &*arg.tok else {
+					let err = mk_errv(
+						ctx.sys.i().i("Syntax error after macros").await,
+						"This token ends up as a binding, consider replacing it with a name",
+						[arg.pos()],
+					);
+					ctx.rep.report(err.clone());
+					return bot(err);
+				};
+				lambda(args.len() as u64, lower_v(body, ctx, args.push(name.clone())).await)
+			},
+			MacTok::Name(name) => match args.iter().enumerate().find(|(_, n)| *n == name) {
+				None => sym_ref(name.clone()),
+				Some((i, _)) => arg((args.len() - i) as u64),
+			},
+			MacTok::Ph(ph) => {
+				let err = mk_errv(
+					ctx.sys.i().i("Placeholder in value").await,
+					format!("Placeholder {ph} is only supported in macro patterns"),
+					[self.pos()],
+				);
+				ctx.rep.report(err.clone());
+				return bot(err);
+			},
+			MacTok::S(Paren::Round, body) => call(lower_v(body, ctx, args).await),
+			MacTok::S(..) => {
+				let err = mk_errv(
+					ctx.sys.i().i("[] or {} after macros").await,
+					format!("{} didn't match any macro", fmt(self, ctx.sys.i()).await),
+					[self.pos()],
+				);
+				ctx.rep.report(err.clone());
+				return bot(err);
+			},
+			MacTok::Slot => panic!("Uninstantiated template should never be exposed"),
+			MacTok::Value(v) => v.clone().to_expr().await,
+		};
+		expr.at(self.pos())
+	}
 }
 impl Atomic for MacTree {
 	type Data = ();
@@ -34,11 +90,20 @@ impl OwnedAtom for MacTree {
 	type Refs = ();
 
 	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
+	async fn print_atom<'a>(&'a self, c: &'a (impl FmtCtx + ?Sized + 'a)) -> FmtUnit {
+		self.tok.print(c).await
+	}
+}
+impl Format for MacTree {
 	async fn print<'a>(&'a self, c: &'a (impl FmtCtx + ?Sized + 'a)) -> FmtUnit {
 		self.tok.print(c).await
 	}
 }
 
+pub async fn lower_v(v: &[MacTree], ctx: LowerCtx<'_>, args: Substack<'_, Sym>) -> Vec<GExpr> {
+	join_all(v.iter().map(|t| t.lower(ctx.clone(), args.clone())).collect::<Vec<_>>()).await
+}
+
 #[derive(Debug, Clone)]
 pub enum MacTok {
 	S(Paren, Vec<MacTree>),
@@ -53,8 +118,17 @@ pub enum MacTok {
 	Bottom(OrcErrv),
 }
 impl MacTok {
+	pub fn build_glossary(&self) -> HashSet<Sym> {
+		match self {
+			MacTok::Bottom(_) | MacTok::Ph(_) | MacTok::Slot | MacTok::Value(_) => HashSet::new(),
+			MacTok::Name(sym) => HashSet::from([sym.clone()]),
+			MacTok::S(_, body) => body.iter().flat_map(|mt| &*mt.glossary).cloned().collect(),
+			MacTok::Lambda(arg, body) =>
+				body.iter().chain([arg]).flat_map(|mt| &*mt.glossary).cloned().collect(),
+		}
+	}
 	pub fn at(self, pos: impl Into<Pos>) -> MacTree {
-		MacTree { pos: pos.into(), tok: Rc::new(self) }
+		MacTree { pos: pos.into(), glossary: Rc::new(self.build_glossary()), tok: Rc::new(self) }
 	}
 }
 impl Format for MacTok {
@@ -77,7 +151,7 @@ impl Format for MacTok {
 				},
 				[mtreev_fmt(body, c).await],
 			),
-			Self::Slot => "SLOT".into(),
+			Self::Slot => "$SLOT".into(),
 			Self::Bottom(err) if err.len() == 1 => format!("Bottom({}) ", err.one().unwrap()).into(),
 			Self::Bottom(err) => format!("Botttom(\n{}) ", indent(&err.to_string())).into(),
 		}
@@ -129,12 +203,12 @@ pub fn map_mactree<F: FnMut(MacTree) -> Option<MacTree>>(
 				ro(changed, |changed| map_mactree(arg, changed, map)),
 				map_mactree_v(body, changed, map),
 			),
-			MacTok::Name(_) | MacTok::Value(_) | MacTok::Slot | MacTok::Ph(_) | MacTok::Bottom(_) =>
-				return src.clone(),
+			MacTok::Name(_) | MacTok::Value(_) => return src.clone(),
+			MacTok::Slot | MacTok::Ph(_) | MacTok::Bottom(_) => return src.clone(),
 			MacTok::S(p, body) => MacTok::S(*p, map_mactree_v(body, changed, map)),
 		},
 	};
-	if *changed { MacTree { pos: src.pos.clone(), tok: Rc::new(tok) } } else { src.clone() }
+	if *changed { tok.at(src.pos()) } else { src.clone() }
 }
 pub fn map_mactree_v<F: FnMut(MacTree) -> Option<MacTree>>(
 	src: &[MacTree],
@@ -152,3 +226,7 @@ fn ro<T>(flag: &mut bool, cb: impl FnOnce(&mut bool) -> T) -> T {
 	*flag |= new_flag;
 	val
 }
+
+pub fn glossary_v(src: &[MacTree]) -> impl Iterator<Item = Sym> {
+	src.iter().flat_map(|mt| mt.glossary()).cloned()
+}