Various progress, doesnt compile

Added prelude, made lambdas a single-token prefix like NS, made progress on implementations, removed const line type

orchid-std/src/macros/let_line.rs

@@ -0,0 +1,59 @@
+use futures::future::LocalBoxFuture;
+use itertools::Itertools;
+use orchid_base::error::{OrcRes, mk_errv};
+use orchid_base::interner::Tok;
+use orchid_base::name::Sym;
+use orchid_base::parse::{Comment, ParseCtx, Parsed, expect_tok, token_errv, try_pop_no_fluff};
+use orchid_extension::gen_expr::GExpr;
+use orchid_extension::parser::{
+	ConstCtx, GenSnippet, ParsCtx, ParsedLine, ParsedLineKind, ParsedMem, ParsedMemKind, Parser,
+};
+use substack::Substack;
+
+type ExprGenerator =
+	Box<dyn for<'a> FnOnce(ConstCtx, Substack<'a, Sym>) -> LocalBoxFuture<'a, GExpr>>;
+
+#[derive(Default)]
+pub struct LetLine;
+impl Parser for LetLine {
+	const LINE_HEAD: &'static str = "let";
+	async fn parse<'a>(
+		ctx: ParsCtx<'a>,
+		exported: bool,
+		comments: Vec<Comment>,
+		line: GenSnippet<'a>,
+	) -> OrcRes<Vec<ParsedLine>> {
+		let Parsed { output: name_tok, tail } = try_pop_no_fluff(&ctx, line).await?;
+		let Some(name) = name_tok.as_name() else {
+			let err = token_errv(&ctx, name_tok, "Constant must have a name", |t| {
+				format!("Expected a name but found {t}")
+			});
+			return Err(err.await);
+		};
+		let Parsed { tail, .. } = expect_tok(&ctx, tail, ctx.i().i("=").await).await?;
+		fn do_tokv(line: GenSnippet<'_>) -> ExprGenerator {
+			let first: ExprGenerator = if let Some((idx, arg)) =
+				line.iter().enumerate().find_map(|(i, x)| Some((i, x.as_lambda()?)))
+			{
+				Box::new(move |ctx, stack| Box::pin(async move {
+					let name = ctx.names([])
+				}))
+			} else {
+
+			};
+			todo!()
+		}
+		let expr_generator = do_tokv(tail);
+		Ok(vec![ParsedLine {
+			comments,
+			sr: line.sr(),
+			kind: ParsedLineKind::Mem(ParsedMem {
+				exported,
+				name,
+				kind: ParsedMemKind::cnst(async |ctx| expr_generator(ctx, Substack::Bottom).await),
+			}),
+		}])
+	}
+}
+
+fn update_names(tree: MacTree)