From d816583a8cfd5568f9c564c9d7b776a2656c6e9f Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 12:06:19 -0300 Subject: [PATCH 1/8] A string literal is one Lit node in the checker: no memory and no stack frame per character, and the emitted code is the same The parser turned "text" into SCon{Chr{U32{WCon{..}}}, ..}, about 70 nodes per character; the checker lifted, copied, checked and kept the chain, so a literal cost about 40 KB per character and one past about 5000 characters overflowed the host stack in term_check, as a Nat literal did before 2.0.7. A string literal now parses as one Lit node holding its text, typed String, that unfolds a character at a time where a chain is read: a match frame in term_wnf, term_compare against a constructor, term_descend against a constructor column, a literal pattern, and check-lit's fallback for any type but String. comp.ts expands every literal back into its chain in def_body, so the emitted C and JS are byte-identical to main for every test. 50 defs of a 1000-character literal: 2.60 GB and 4.00 s to 74 MB and 0.14 s; a 200,000-character literal checks in 0.17 s. A literal that spells a surrogate or a code point past U+10FFFF still parses as its chain. bend2/bend.ts may reach 43500 ttok (41915 to 43203). Four tests. Co-Authored-By: Claude Fable 5.1 --- bend2/bend.ts | 134 ++++++++++++++++++--- bend2/comp.ts | 2 +- gates/repo.ts | 2 +- tests/check/string_literal_long.bend | 13 ++ tests/check/string_literal_surrogates.bend | 9 ++ tests/printer/string_literal_tail.bend | 14 +++ tests/proof/string_literal_unfolds.bend | 63 ++++++++++ 7 files changed, 217 insertions(+), 20 deletions(-) create mode 100644 tests/check/string_literal_long.bend create mode 100644 tests/check/string_literal_surrogates.bend create mode 100644 tests/printer/string_literal_tail.bend create mode 100644 tests/proof/string_literal_unfolds.bend diff --git a/bend2/bend.ts b/bend2/bend.ts index 35db96c73b..4ab5d411da 100644 --- a/bend2/bend.ts +++ b/bend2/bend.ts @@ -70,7 +70,7 @@ // U32 | NUMBER | U32{WCon{b, ..WNil{}}} // F32 | NUMBER "." NUMBER [EXP] | F32{WCon{b, ..WNil{}}} // Chr | "'" CHAR "'" | Chr{U32} -// Str | "\"" [CHAR] "\"" | SCon{Chr, ..SNil{}} +// Str | "\"" [CHAR] "\"" | Lit, read as SCon{Chr, ..SNil{}} // Index | x "[" i "]" ("<-" v)? | Array.get(U32, x, i), ..set(..) // Fill | D "<" [A ","?] ">" | D<&1.., A..> // Plus | "+" D ("<" [A ","?] ">")? | D<&2.., A..> @@ -90,7 +90,9 @@ // "->" return type. a def after its law takes bare names, no "->". // a bare Bind name is -Name: Quant. Fill and Plus omit a datatype's // leading Quant parameters as a block; Plus alone fills a quant-only D. -// a literal expands to one node per unit, unbounded by design; a full +// a literal expands to one node per unit, unbounded by design, but a +// string stays one Lit node and unfolds a character at a time where a +// chain is read (a match, a comparison, a descent, a pattern); a full // word, a Nat, a Char, a String, a list, a tuple and an array (its // slots) print back as literals; "*" takes a power of two. Arrow is // right-associative; the domain of a written @ or & binder stops at the @@ -286,6 +288,7 @@ export type TermOf = ( | { $: "App"; f: TermOf; x: TermOf } // f(x) | { $: "ADT"; k: Name; x: TermOf[]; r: Name[] } // A | { $: "Ctr"; k: Name; x: TermOf[] } // A{x0,x1,...} + | { $: "Lit"; v: string } // "text" | { $: "Mat"; k: Name; h: TermOf; m: TermOf } // \{A: h; m} | { $: "Efq" } // \{} | { $: "Eql"; a: TermOf; b: TermOf; T: TermOf } // {a == b : T} @@ -407,6 +410,10 @@ export function Ctr(k: Name, x: TermOf[], s?: Span): TermOf { return { $: "Ctr", k, x, s }; } +export function Lit(v: string, s?: Span): TermOf { + return { $: "Lit", v, s }; +} + export function Mat(k: Name, h: TermOf, m: TermOf, s?: Span): TermOf { return { $: "Mat", k, h, m, s }; } @@ -785,6 +792,9 @@ export function term_higher(tm: LTerm, env: Env = null): HTerm { case "Ctr": { return Ctr(tm.k, tm.x.map((x) => term_higher(x, env)), tm.s); } + case "Lit": { + return tm; + } case "Mat": { return Mat(tm.k, term_higher(tm.h, env), term_higher(tm.m, env), tm.s); } @@ -853,6 +863,9 @@ export function term_lower(term: HTerm, d: number = 0): LTerm { case "Ctr": { return Ctr(tm.k, tm.x.map((x) => term_lower(x, d)), tm.s); } + case "Lit": { + return tm; + } case "Mat": { return Mat(tm.k, term_lower(tm.h, d), term_lower(tm.m, d), tm.s); } @@ -881,8 +894,9 @@ export function term_descend(q: Quant, arg: HTerm, col: HTerm): Cmp { if (q.$ === "None") { return "EQ"; } - const a = term_strip(arg); + const s = term_strip(arg); const p = term_strip(col); + const a = s.$ === "Lit" && p.$ === "Ctr" ? term_higher(lit_step(s)) : s; switch (p.$) { case "Var": { if (a.$ === "Var" && a.i === p.i) { @@ -1160,6 +1174,53 @@ export function u32_to_term(n: U32, s?: Span): LTerm { return Ctr("U32", [word_to_term(n, s)], s); } +// Lit +// === +// a string literal is one node holding its text: it means the SCon chain +// of its characters and unfolds a character at a time where a chain is +// read, so the checker pays nothing per character and no literal outgrows +// its stack. a JS string holds Unicode scalar values only, so a literal +// that spells a surrogate or a code point past U+10FFFF is its chain. + +export function lit_of(cs: U32[], s?: Span): LTerm { + return cs.every((c) => c <= 0x10ffff && (c < 0xd800 || c > 0xdfff)) + ? Lit(cs.map((c) => String.fromCodePoint(c)).join(""), s) : lit_chain(cs, s); +} + +export function lit_chain(cs: U32[], s?: Span): LTerm { + return cs.reduceRight((out, c) => + Ctr("SCon", [Ctr("Chr", [u32_to_term(c, s)], s), out], s), Ctr("SNil", [], s)); +} + +// one step: "" is SNil{}, "ct.." is SCon{Chr{c}, "t.."} +export function lit_step(t: Extract): LTerm { + const c = t.v.codePointAt(0); + return c === undefined ? Ctr("SNil", [], t.s) + : Ctr("SCon", [Ctr("Chr", [u32_to_term(c, t.s)], t.s), Lit(t.v.slice(c > 0xffff ? 2 : 1), t.s)], t.s); +} + +// every literal in a first-order term as its chain: the compiler's view +export function lit_expand(tm: LTerm): LTerm { + const go = lit_expand; + switch (tm.$) { + case "Lit": return lit_chain([...tm.v].map((c) => c.codePointAt(0) as U32), tm.s); + case "Var": case "Ref": case "Qnt": case "Qua": case "Efq": case "Rfl": case "Hol": return tm; + case "Sub": return Sub(tm.i, tm.v.$ === "PVar" || tm.v.$ === "PCtr" ? tm.v : go(tm.v), go(tm.f), tm.s); + case "Let": return Let(tm.k, tm.i, tm.v.map(go), go(tm.f), tm.s, tm.q); + case "Typ": return Typ(go(tm.g), tm.s); + case "Min": return Min(go(tm.a), go(tm.b), tm.s); + case "All": return All(tm.q, tm.k, tm.i, go(tm.A), go(tm.B), tm.s); + case "Lam": return Lam(tm.k, tm.i, go(tm.f), tm.s, tm.q); + case "App": return App(go(tm.f), go(tm.x), tm.s); + case "ADT": return ADT(tm.k, tm.x.map(go), tm.s, tm.r); + case "Ctr": return Ctr(tm.k, tm.x.map(go), tm.s); + case "Mat": return Mat(tm.k, go(tm.h), go(tm.m), tm.s); + case "Eql": return Eql(go(tm.a), go(tm.b), go(tm.T), tm.s); + case "Rwt": return Rwt(go(tm.e), go(tm.p), go(tm.f), tm.s); + case "Ann": return Ann(go(tm.x), go(tm.T), tm.s); + } +} + // A nat literal up to NAT_LITERAL_MAX expands into a Succ chain, which the // checker unfolds in patterns and proofs; a larger one, up to the u32 bound, // parses as U32.to_nat(n), so no chain outgrows the checker's stack. @@ -1321,12 +1382,7 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri } return l.concat(r); } - function term_show_sugar_chr(tm: LTerm, quote: string): string | null { - const n = tm.$ === "Ctr" && tm.k === "Chr" && tm.x.length === 1 - ? u32_from_term(tm.x[0]) : null; - if (n === null) { - return null; - } + function chr_show(n: U32, quote: string): string { const k = Object.keys(ESCAPES).find((k) => ESCAPES[k] === n && ((k !== "'" && k !== '"') || k === quote)); if (k !== undefined) { return "\\" + k; @@ -1336,13 +1392,23 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri } return String.fromCodePoint(n); } + function lit_text(v: string): string { + return [...v].map((c) => chr_show(c.codePointAt(0) as U32, "\"")).join(""); + } + function term_show_sugar_chr(tm: LTerm, quote: string): string | null { + const n = tm.$ === "Ctr" && tm.k === "Chr" && tm.x.length === 1 + ? u32_from_term(tm.x[0]) : null; + return n === null ? null : chr_show(n, quote); + } function term_show_sugar_str(tm: LTerm): string | null { const [cs, t] = term_show_chain(tm, "SCon", 2); const ss = cs.map((c) => term_show_sugar_chr(c, "\"")); - if (t.$ !== "Ctr" || t.k !== "SNil" || t.x.length !== 0 || ss.includes(null)) { + const tl = t.$ === "Lit" ? lit_text(t.v) + : t.$ === "Ctr" && t.k === "SNil" && t.x.length === 0 ? "" : null; + if (tl === null || ss.includes(null)) { return null; } - return "\"" + ss.join("") + "\""; + return "\"" + ss.join("") + tl + "\""; } function go(tm: LTerm, prc: number): string { switch (tm.$) { @@ -1435,6 +1501,9 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri const as = tm.x.map((x) => go(x, 0)); return tm.k + "{" + as.join(", ") + "}"; } + case "Lit": { + return "\"" + lit_text(tm.v) + "\""; + } case "Mat": { const arms: string[] = []; let m: LTerm = tm; @@ -1763,6 +1832,9 @@ export function parse_patt(p: Parse, t: LTerm): Patt { } return { $: "PCtr", k: t.k, x: t.x.map((x) => parse_patt(p, x)), s: t.s }; } + case "Lit": { + return parse_patt(p, lit_expand(t)); + } default: { throw Err(book, ctx_nil(), "a pattern (a binder or a constructor)", term_show(term_lower(term_higher(t), 0)), t.s); } @@ -1996,10 +2068,7 @@ export function parse_term_base(p: Parse, beg: Loc): LTerm { } cs.push(parse_char(p)); } - const spn = parse_span(p, beg); - return cs.reduceRight((out, c) => - Ctr("SCon", [Ctr("Chr", [u32_to_term(c, spn)], spn), out], spn), - Ctr("SNil", [], spn)); + return lit_of(cs, parse_span(p, beg)); } case "?": { parse_bump(p); @@ -2720,7 +2789,8 @@ export function match_flatten(m: Match, vars: PVar[], fr: () => number): LTerm { + " name is a def or a consumed binder: give the value its own def)", undefined, e.s); } - case "Ctr": { + case "Ctr": + case "Lit": { throw Err(book_nil(), ctx_nil(), "an undestructed scrutinee (this value is already a constructor: bind its fields directly; if an outer match destructed it, fold the pattern into the outer case)", undefined, m.s); } default: { @@ -3012,6 +3082,9 @@ export function term_wnf(book: Book, term: HTerm): HTerm { continue back; } case "MAT": { + if (tm.$ === "Lit") { + tm = term_higher(lit_step(tm)); + } if (tm.$ === "Ctr") { const ctr = tm; let t: HTerm = fr.t; @@ -3106,6 +3179,9 @@ export function term_snf(book: Book, term: HTerm): HTerm { case "Ctr": { return Ctr(tm.k, tm.x.map((x) => term_snf(book, x)), tm.s); } + case "Lit": { + return tm; + } case "Mat": { return Mat(tm.k, term_snf(book, tm.h), term_snf(book, tm.m), tm.s); } @@ -3145,8 +3221,8 @@ export function term_compare(mode: "EQ" | "LE", book: Book, lhs: HTerm, rhs: HTe if (lhs === rhs) { return true; } - const a = term_wnf(book, lhs); - const b = term_wnf(book, rhs); + let a = term_wnf(book, lhs); + let b = term_wnf(book, rhs); if (a === b) { return true; } @@ -3155,6 +3231,12 @@ export function term_compare(mode: "EQ" | "LE", book: Book, lhs: HTerm, rhs: HTe const x: HTerm = Var(k, dep); return term_compare(mode, book, term_apply(a, x), term_apply(b, x), dep + 1); } + if (a.$ === "Lit" && b.$ === "Ctr") { + a = term_higher(lit_step(a)); + } + if (b.$ === "Lit" && a.$ === "Ctr") { + b = term_higher(lit_step(b)); + } switch (a.$) { case "Var": { return b.$ === "Var" && a.i === b.i; @@ -3222,6 +3304,9 @@ export function term_compare(mode: "EQ" | "LE", book: Book, lhs: HTerm, rhs: HTe return b.$ === "Ctr" && a.k === b.k && a.x.length === b.x.length && a.x.every((x, j) => term_compare("EQ", book, x, b.x[j], dep)); } + case "Lit": { + return b.$ === "Lit" && a.v === b.v; + } case "Mat": { return b.$ === "Mat" && a.k === b.k && term_compare("EQ", book, a.h, b.h, dep) @@ -3559,6 +3644,19 @@ export function term_check(book: Book, lhs: LHS, tm: HTerm, qt: Quant, ty: HTerm const { xs, us } = tele_check(book, lhs, tel, tm.x, qt, ctx, d, tm.s); return Check(Ctr(tm.k, xs, tm.s), ty, us); } + // T == String, with the literal's head (SNil for "", else SCon) + // where any other T checks the literal's first step, which reports + // as the constructor it is + // ----------------------------------------------------------- check-lit + // Γ ⊢ "text" : T ~ {} + case "Lit": { + const t_wnf = term_wnf(book, ty); + if (t_wnf.$ === "ADT" && t_wnf.k === "String" + && ctrs_find(book_adt(book, t_wnf, ctx, lhs.def).c, tm.v === "" ? "SNil" : "SCon") !== null) { + return Check(tm, ty, uses_nil()); + } + return term_check(book, lhs, term_higher(lit_step(tm)), qt, ty, ctx, d); + } // T == @q s:D -> P // D.c[k] = @r1 x1:F1 -> .. -> D // Γ ⊢ h : @s1 x1:F1 -> .. -> P(k{x1, .., xn}) ~ hu diff --git a/bend2/comp.ts b/bend2/comp.ts index 8576a3c74e..d6210a6b27 100644 --- a/bend2/comp.ts +++ b/bend2/comp.ts @@ -1424,7 +1424,7 @@ function anf(cb: Carb, t: HTerm, ty: HTerm | null = null): HTerm { function def_body(cb: Carb, k: Bend.Name): TLD | undefined { const tld = cb.book.tlds[k]; if (tld?.$ === "Def" && tld.e !== undefined && tld.h === undefined) { - const h = Bend.term_higher(tld.e); + const h = Bend.term_higher(Bend.lit_expand(tld.e)); const n = tld.n + Math.min(def_raise(cb.book, h, tld.n), tele_unbind(cb.book, tld.T).doms.length - tld.n); cb.book.tlds[k] = { ...tld, n, h }; diff --git a/gates/repo.ts b/gates/repo.ts index 352704d3a8..ca6fa94b41 100644 --- a/gates/repo.ts +++ b/gates/repo.ts @@ -39,7 +39,7 @@ allow("LICENSE", 4000); allow("flake.nix", 1500); allow("bend2/base.bend", 32000); allow("bend2/bend.lean", 400000); -allow("bend2/bend.ts", 42000); +allow("bend2/bend.ts", 43500); allow("bend2/comp.ts", 65000); allow("bend2/main.ts", 10000); allow(/^bend2\/effs\/[a-z0-9_]+\.(c|js)$/, 4000); diff --git a/tests/check/string_literal_long.bend b/tests/check/string_literal_long.bend new file mode 100644 index 0000000000..51e9dd3a93 --- /dev/null +++ b/tests/check/string_literal_long.bend @@ -0,0 +1,13 @@ +# a 6000-character string literal checks: the checker holds a literal as +# one Lit node, not as a constructor per character (which overflowed its +# stack near 5000 characters). main is a function, so the test is checked +# and interpreted; the interpreter unfolds the literal to count it. +import Base + +def text() -> String: + 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+ +def main(n: Nat) -> Nat: + Nat.add(n, String.length(text())) + +#|n => Nat.add(n, 6000n) diff --git a/tests/check/string_literal_surrogates.bend b/tests/check/string_literal_surrogates.bend new file mode 100644 index 0000000000..7aed1e9096 --- /dev/null +++ b/tests/check/string_literal_surrogates.bend @@ -0,0 +1,9 @@ +# a literal that spells a surrogate is not one JS string's worth of +# Unicode scalar values, so it parses as its constructor chain and still +# means two characters +import Base + +def main() -> Nat: + String.length("\u{d83d}\u{de00}") + +#|2n diff --git a/tests/printer/string_literal_tail.bend b/tests/printer/string_literal_tail.bend new file mode 100644 index 0000000000..ec7050e769 --- /dev/null +++ b/tests/printer/string_literal_tail.bend @@ -0,0 +1,14 @@ +# a literal prints back as a literal, and a chain that ends in a literal +# prints as one string: SCon{'a', SCon{'b', "cd"}} is "abcd" +import Base + +def greet(b: Bool) -> String: + Bool.pick(String, b, "yes\"\n", "no") + +def cons(s: String) -> String: + SCon{'a', SCon{'b', s}} + +def main(b: Bool) -> String: + String.append(greet(b), cons("cd")) + +#|b => String.append(Bool.pick(String, b, "yes\"\n", "no"), "abcd") diff --git a/tests/proof/string_literal_unfolds.bend b/tests/proof/string_literal_unfolds.bend new file mode 100644 index 0000000000..dcfbc89129 --- /dev/null +++ b/tests/proof/string_literal_unfolds.bend @@ -0,0 +1,63 @@ +# a string literal is one Lit node in the checker; it unfolds a character +# at a time where a chain is read: a comparison sees "ab" as +# SCon{'a', "b"}, "" as SNil{}, a match reads a literal pattern and a +# literal scrutinee, and the evaluator steps through a literal's length. +import Base + +law ab_is_chain: + {"ab" == SCon{'a', "b"} : String} + +def ab_is_chain(): + {==} + +law empty_is_nil: + {"" == SNil{} : String} + +def empty_is_nil(): + {==} + +law length_three: + {String.length("abc") == 3n : Nat} + +def length_three(): + {==} + +law append_lits: + {String.append("ab", "cd") == "abcd" : String} + +def append_lits(): + {==} + +law eq_lits: + {String.eq("héllo", "héllo") == True{} : Bool} + +def eq_lits(): + {==} + +def classify(s: String) -> Nat: + match s: + case "": + 0n + case "one": + 1n + case "two": + 2n + case _: + 9n + +law classify_two: + {classify("two") == 2n : Nat} + +def classify_two(): + {==} + +law classify_more: + {classify("twoo") == 9n : Nat} + +def classify_more(): + {==} + +def main() -> List<&2, Nat>: + [classify(""), classify("one"), classify("two"), classify("x"), String.length("😀é")] + +#|[0n, 1n, 2n, 9n, 2n] From 75deac166ad721d31710d71952252675d9c18d8a Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 19:59:57 -0300 Subject: [PATCH 2/8] The surrogate test is a law, not a main: the JS runtime rejects a lone surrogate tests/check/string_literal_surrogates.bend ran String.length("\u{d83d}\u{de00}") in main, and every test with a main and Base runs in the C and JS lanes; the JS runtime aborts on a lone surrogate (as on main), so the gate would fail. The same check is now the law surrogates_two in tests/proof/string_literal_unfolds.bend, which the checker verifies and the compiler never emits. Co-Authored-By: Claude Fable 5.1 --- tests/check/string_literal_surrogates.bend | 9 --------- tests/proof/string_literal_unfolds.bend | 7 +++++++ 2 files changed, 7 insertions(+), 9 deletions(-) delete mode 100644 tests/check/string_literal_surrogates.bend diff --git a/tests/check/string_literal_surrogates.bend b/tests/check/string_literal_surrogates.bend deleted file mode 100644 index 7aed1e9096..0000000000 --- a/tests/check/string_literal_surrogates.bend +++ /dev/null @@ -1,9 +0,0 @@ -# a literal that spells a surrogate is not one JS string's worth of -# Unicode scalar values, so it parses as its constructor chain and still -# means two characters -import Base - -def main() -> Nat: - String.length("\u{d83d}\u{de00}") - -#|2n diff --git a/tests/proof/string_literal_unfolds.bend b/tests/proof/string_literal_unfolds.bend index dcfbc89129..2126f57368 100644 --- a/tests/proof/string_literal_unfolds.bend +++ b/tests/proof/string_literal_unfolds.bend @@ -2,6 +2,7 @@ # at a time where a chain is read: a comparison sees "ab" as # SCon{'a', "b"}, "" as SNil{}, a match reads a literal pattern and a # literal scrutinee, and the evaluator steps through a literal's length. +# a character is any u32, so a literal may spell a surrogate pair. import Base law ab_is_chain: @@ -34,6 +35,12 @@ law eq_lits: def eq_lits(): {==} +law surrogates_two: + {String.length("\u{d83d}\u{de00}") == 2n : Nat} + +def surrogates_two(): + {==} + def classify(s: String) -> Nat: match s: case "": From 6619790bbc109b1eca73cbb79e64961d4144ff15 Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 20:11:03 -0300 Subject: [PATCH 3/8] lit_expand is gone: a pattern expands its literal in place, and the compiler expands a literal where it reads a constructor lit_expand walked a whole first-order term to turn every Lit into its chain before compilation, so comp.ts saw no Lit. A Lit has no sub-terms, so parse_patt calls lit_full, the chain of one literal. The compiler matches constructors in term_const, ty_peel and the Mat scrutinee of emit_unfold, so term_lit, memoized per node, hands them a Lit's chain there, and def_body no longer pre-expands. The emitted code is unchanged: the JS of the 164 runnable tests with a string literal is byte-identical, and the checker's output is the same on every non-IO test. bend2/bend.ts may reach 43000 ttok (43203 to 42853). Co-Authored-By: Claude Fable 5.1 --- bend2/bend.ts | 25 ++++--------------------- bend2/comp.ts | 17 ++++++++++++----- gates/repo.ts | 2 +- 3 files changed, 17 insertions(+), 27 deletions(-) diff --git a/bend2/bend.ts b/bend2/bend.ts index 4ab5d411da..8d470e9094 100644 --- a/bend2/bend.ts +++ b/bend2/bend.ts @@ -1199,26 +1199,9 @@ export function lit_step(t: Extract): LTerm { : Ctr("SCon", [Ctr("Chr", [u32_to_term(c, t.s)], t.s), Lit(t.v.slice(c > 0xffff ? 2 : 1), t.s)], t.s); } -// every literal in a first-order term as its chain: the compiler's view -export function lit_expand(tm: LTerm): LTerm { - const go = lit_expand; - switch (tm.$) { - case "Lit": return lit_chain([...tm.v].map((c) => c.codePointAt(0) as U32), tm.s); - case "Var": case "Ref": case "Qnt": case "Qua": case "Efq": case "Rfl": case "Hol": return tm; - case "Sub": return Sub(tm.i, tm.v.$ === "PVar" || tm.v.$ === "PCtr" ? tm.v : go(tm.v), go(tm.f), tm.s); - case "Let": return Let(tm.k, tm.i, tm.v.map(go), go(tm.f), tm.s, tm.q); - case "Typ": return Typ(go(tm.g), tm.s); - case "Min": return Min(go(tm.a), go(tm.b), tm.s); - case "All": return All(tm.q, tm.k, tm.i, go(tm.A), go(tm.B), tm.s); - case "Lam": return Lam(tm.k, tm.i, go(tm.f), tm.s, tm.q); - case "App": return App(go(tm.f), go(tm.x), tm.s); - case "ADT": return ADT(tm.k, tm.x.map(go), tm.s, tm.r); - case "Ctr": return Ctr(tm.k, tm.x.map(go), tm.s); - case "Mat": return Mat(tm.k, go(tm.h), go(tm.m), tm.s); - case "Eql": return Eql(go(tm.a), go(tm.b), go(tm.T), tm.s); - case "Rwt": return Rwt(go(tm.e), go(tm.p), go(tm.f), tm.s); - case "Ann": return Ann(go(tm.x), go(tm.T), tm.s); - } +// the whole chain: a pattern's and the compiler's view +export function lit_full(t: Extract): LTerm { + return lit_chain([...t.v].map((c) => c.codePointAt(0) as U32), t.s); } // A nat literal up to NAT_LITERAL_MAX expands into a Succ chain, which the @@ -1833,7 +1816,7 @@ export function parse_patt(p: Parse, t: LTerm): Patt { return { $: "PCtr", k: t.k, x: t.x.map((x) => parse_patt(p, x)), s: t.s }; } case "Lit": { - return parse_patt(p, lit_expand(t)); + return parse_patt(p, lit_full(t)); } default: { throw Err(book, ctx_nil(), "a pattern (a binder or a constructor)", term_show(term_lower(term_higher(t), 0)), t.s); diff --git a/bend2/comp.ts b/bend2/comp.ts index d6210a6b27..667382d115 100644 --- a/bend2/comp.ts +++ b/bend2/comp.ts @@ -631,6 +631,8 @@ const CYCLES: Map = new Map(); const CONSTS: Map = new Map(); +const LITS: Map = new Map(); + // Name // ==== @@ -696,7 +698,7 @@ function memo(m: Map, k: K, f: () => V): V { } function memo_gc(): void { - [OPENS, USES, FOLDS, SPINES, CONSTS].forEach((m) => m.clear()); + [OPENS, USES, FOLDS, SPINES, CONSTS, LITS].forEach((m) => m.clear()); } // Probe @@ -828,8 +830,13 @@ function term_nodes(cf: Carb, t: HTerm): number { return n; } +// A string literal is its constructor chain to the compiler. +function term_lit(t: HTerm): HTerm { + return t.$ === "Lit" ? memo(LITS, t, () => Bend.term_higher(Bend.lit_full(t))) : t; +} + function term_const(t: HTerm): boolean { - const s = Bend.term_strip(t); + const s = term_lit(Bend.term_strip(t)); return s.$ === "Ctr" && memo(CONSTS, s, () => s.x.every(term_const)); } @@ -929,7 +936,7 @@ function ty_peel(tm: HTerm, ty = x.$ === "Ann" ? x.T : ty; x = Bend.term_force(x.$ === "Ann" ? x.x : x.f); } - return [x, ty]; + return [term_lit(x), ty]; } function ty_adt(book: Bend.Book, A: HTerm | null): HAdt | null { @@ -1424,7 +1431,7 @@ function anf(cb: Carb, t: HTerm, ty: HTerm | null = null): HTerm { function def_body(cb: Carb, k: Bend.Name): TLD | undefined { const tld = cb.book.tlds[k]; if (tld?.$ === "Def" && tld.e !== undefined && tld.h === undefined) { - const h = Bend.term_higher(Bend.lit_expand(tld.e)); + const h = Bend.term_higher(tld.e); const n = tld.n + Math.min(def_raise(cb.book, h, tld.n), tele_unbind(cb.book, tld.T).doms.length - tld.n); cb.book.tlds[k] = { ...tld, n, h }; @@ -2389,7 +2396,7 @@ function emit_unfold(fl: File, s: HTerm): HTerm | null { xs = xs.slice(1); continue; } - const c = w.$ === "Mat" ? Bend.term_strip(xs[0]) : null; + const c = w.$ === "Mat" ? term_lit(Bend.term_strip(xs[0])) : null; if (c === null || c.$ !== "Ctr" || !term_const(c)) { return null; } diff --git a/gates/repo.ts b/gates/repo.ts index ca6fa94b41..d1df0b5f39 100644 --- a/gates/repo.ts +++ b/gates/repo.ts @@ -39,7 +39,7 @@ allow("LICENSE", 4000); allow("flake.nix", 1500); allow("bend2/base.bend", 32000); allow("bend2/bend.lean", 400000); -allow("bend2/bend.ts", 43500); +allow("bend2/bend.ts", 43000); allow("bend2/comp.ts", 65000); allow("bend2/main.ts", 10000); allow(/^bend2\/effs\/[a-z0-9_]+\.(c|js)$/, 4000); From 105d0ded25b4bbe950e768b36a1bb92b60c9042a Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 20:13:28 -0300 Subject: [PATCH 4/8] Two tests pin where a literal must unfold: the termination check and a module's own String Both hold on main and had no test. A literal argument that is a strict tail of its case's literal pattern descends: case "ab" may call f("b"), which needs term_descend to read the literal as its chain. A literal is a String only where String declares SCon and SNil: a module that declares its own type String is Data: Foo{} rejects "abc" with main's exact error, which needs check-lit's ctrs_find guard. Co-Authored-By: Claude Fable 5.1 --- tests/check/string_literal_descends.bend | 15 +++++++++++++++ tests/check/string_literal_own_string.bend | 16 ++++++++++++++++ 2 files changed, 31 insertions(+) create mode 100644 tests/check/string_literal_descends.bend create mode 100644 tests/check/string_literal_own_string.bend diff --git a/tests/check/string_literal_descends.bend b/tests/check/string_literal_descends.bend new file mode 100644 index 0000000000..93bbaf2483 --- /dev/null +++ b/tests/check/string_literal_descends.bend @@ -0,0 +1,15 @@ +# a literal argument descends when it is a strict tail of its case's +# literal pattern: the termination check unfolds the literal +import Base + +def f(s: String) -> Nat: + match s: + case "ab": + f("b") + case _: + 0n + +def main() -> Nat: + f("ab") + +#|0n diff --git a/tests/check/string_literal_own_string.bend b/tests/check/string_literal_own_string.bend new file mode 100644 index 0000000000..433b2da91c --- /dev/null +++ b/tests/check/string_literal_own_string.bend @@ -0,0 +1,16 @@ +# a literal is a String only where String declares SCon and SNil: a +# module's own String with other constructors rejects it +type String is Data: + Foo{} + +def s() -> String: + "abc" + +#|Error: +#|- expected : a declared constructor (String declares Foo) +#|- observed : "abc" +#|Location: s +#|6 | def s() -> String: +#|7>| "abc" +#|8 | +#|exit 1 From 5ca8f72fa570fe3f815cee73ab1fa8e7fe3feb03 Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 21:15:23 -0300 Subject: [PATCH 5/8] The literal-pattern test spells its pattern 0n, not the longhand U32.to_nat(0) The test proves a literal pattern is refused like Zero{} is when Zero carries a field. It wrote the pattern as U32.to_nat(0), the form the parser gave a nat literal, which reads as a test of that longhand. It now writes 0n, the literal it is about, and prints the same error. Co-Authored-By: Claude Fable 5.1 --- tests/check/nat_literal_pattern_empty.bend | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tests/check/nat_literal_pattern_empty.bend b/tests/check/nat_literal_pattern_empty.bend index 59a30218fe..f33f6c19b3 100644 --- a/tests/check/nat_literal_pattern_empty.bend +++ b/tests/check/nat_literal_pattern_empty.bend @@ -1,7 +1,7 @@ # the unchecked literal pattern let a closed term inhabit Empty: the -# longhand U32.to_nat(0) matched a Zero that carries a field as a bare -# Zero, the arm's goal became @w:U -> Empty, and the self-call f(q) -# passed without descending. the literal is refused like Zero{} is +# literal 0n matched a Zero that carries a field as a bare Zero, the +# arm's goal became @w:U -> Empty, and the self-call f(q) passed without +# descending. the literal is refused like Zero{} is type U is Data: Un{} type N is Data: @@ -13,7 +13,7 @@ type Empty is Data: def f(b: N) -> Empty: match b: - case U32.to_nat(0): + case 0n: {\{K: q => w => f(q)} : D -> U -> Empty}(K{Zero{Un{}}}) case Succ{p}: f(p) @@ -25,6 +25,6 @@ def boom() -> Empty: #|- message : a Zero pattern with 1 field #|Location: #|15 | match b: -#|16>| case U32.to_nat(0): +#|16>| case 0n: #|17 | {\{K: q => w => f(q)} : D -> U -> Empty}(K{Zero{Un{}}}) #|exit 1 From ffaf6313df1d7d755dad20c3a4ecb2128461d514 Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 21:15:24 -0300 Subject: [PATCH 6/8] A nat literal is one Lit node in the checker, as a string literal is, and the emitted code is the same A nat literal up to 256 was a Succ chain and a larger one U32.to_nat(n), an application, so two forms meant one literal: the parser, the pattern reader and the printer each knew both, and a self-call on a literal past 256 failed the termination check. A Lit now holds a number as it holds a text: it unfolds a Succ at a time where a chain is read (a match frame, a comparison, a descent, the check rule's fallback), checks in O(1) against Nat, infers through its first step (so an undeclared Nat still reports "a declared constructor"), prints as its number (a Succ chain that ends in a literal prints as one number), and "1n+0n" parses as 1n so template keys agree. NAT_LITERAL_MAX stays for "n + T", which is Nat.add(n, T) past it, and for the compiler, whose term_lit emits U32.to_nat(n) past it and whose term_kids and term_any read a literal through it, so the C and JS of every test are byte-identical. The checker's output is the same on every non-IO test. 2000 defs of 200n: 1.06 s and 366 MB to 0.18 s and 83 MB. Co-Authored-By: Claude Fable 5.1 --- bend2/bend.ts | 99 ++++++++++++++++++++++++--------------------------- bend2/comp.ts | 9 ++--- 2 files changed, 51 insertions(+), 57 deletions(-) diff --git a/bend2/bend.ts b/bend2/bend.ts index 8d470e9094..608f4b47e1 100644 --- a/bend2/bend.ts +++ b/bend2/bend.ts @@ -66,7 +66,7 @@ // Tuple | "(" A ("," B)+ ")" | Tuple{A, Tuple{B, ..}} // List | "[" [A ","?] "]", A "<>" B | Con{A, ..Nil{}}, Con{A, B} // Array | "[" A ":" T ("*" 2^D "n" | "^" D) "]" | Array.new(T, D, A) -// Nat | NUMBER "n" ("+" T)? | Succ{..Zero{}}, Succ{..T} +// Nat | NUMBER "n" ("+" T)? | Lit, read as Succ{..Zero{}}; Succ{..T} // U32 | NUMBER | U32{WCon{b, ..WNil{}}} // F32 | NUMBER "." NUMBER [EXP] | F32{WCon{b, ..WNil{}}} // Chr | "'" CHAR "'" | Chr{U32} @@ -91,8 +91,8 @@ // a bare Bind name is -Name: Quant. Fill and Plus omit a datatype's // leading Quant parameters as a block; Plus alone fills a quant-only D. // a literal expands to one node per unit, unbounded by design, but a -// string stays one Lit node and unfolds a character at a time where a -// chain is read (a match, a comparison, a descent, a pattern); a full +// string and a nat stay one Lit node and unfold a unit at a time where +// a chain is read (a match, a comparison, a descent, a pattern); a full // word, a Nat, a Char, a String, a list, a tuple and an array (its // slots) print back as literals; "*" takes a power of two. Arrow is // right-associative; the domain of a written @ or & binder stops at the @@ -288,7 +288,7 @@ export type TermOf = ( | { $: "App"; f: TermOf; x: TermOf } // f(x) | { $: "ADT"; k: Name; x: TermOf[]; r: Name[] } // A | { $: "Ctr"; k: Name; x: TermOf[] } // A{x0,x1,...} - | { $: "Lit"; v: string } // "text" + | { $: "Lit"; v: string | number } // "text", 3n | { $: "Mat"; k: Name; h: TermOf; m: TermOf } // \{A: h; m} | { $: "Efq" } // \{} | { $: "Eql"; a: TermOf; b: TermOf; T: TermOf } // {a == b : T} @@ -410,7 +410,7 @@ export function Ctr(k: Name, x: TermOf[], s?: Span): TermOf { return { $: "Ctr", k, x, s }; } -export function Lit(v: string, s?: Span): TermOf { +export function Lit(v: string | number, s?: Span): TermOf { return { $: "Lit", v, s }; } @@ -1176,11 +1176,11 @@ export function u32_to_term(n: U32, s?: Span): LTerm { // Lit // === -// a string literal is one node holding its text: it means the SCon chain -// of its characters and unfolds a character at a time where a chain is -// read, so the checker pays nothing per character and no literal outgrows -// its stack. a JS string holds Unicode scalar values only, so a literal -// that spells a surrogate or a code point past U+10FFFF is its chain. +// a string or nat literal is one node holding its text or number: it +// means its chain (SCon per character, Succ per unit) and unfolds one +// unit at a time where a chain is read, so the checker pays nothing per +// unit. a JS string holds Unicode scalar values only, so a literal that +// spells a surrogate or a code point past U+10FFFF is its chain. export function lit_of(cs: U32[], s?: Span): LTerm { return cs.every((c) => c <= 0x10ffff && (c < 0xd800 || c > 0xdfff)) @@ -1192,47 +1192,40 @@ export function lit_chain(cs: U32[], s?: Span): LTerm { Ctr("SCon", [Ctr("Chr", [u32_to_term(c, s)], s), out], s), Ctr("SNil", [], s)); } -// one step: "" is SNil{}, "ct.." is SCon{Chr{c}, "t.."} +// one step: "" is SNil{}, "ct.." is SCon{Chr{c}, "t.."}, 0n is Zero{}, n is Succ{n-1} export function lit_step(t: Extract): LTerm { + if (typeof t.v === "number") { + return t.v === 0 ? Ctr("Zero", [], t.s) : Ctr("Succ", [Lit(t.v - 1, t.s)], t.s); + } const c = t.v.codePointAt(0); return c === undefined ? Ctr("SNil", [], t.s) : Ctr("SCon", [Ctr("Chr", [u32_to_term(c, t.s)], t.s), Lit(t.v.slice(c > 0xffff ? 2 : 1), t.s)], t.s); } -// the whole chain: a pattern's and the compiler's view +// the whole chain: a pattern's view export function lit_full(t: Extract): LTerm { - return lit_chain([...t.v].map((c) => c.codePointAt(0) as U32), t.s); -} - -// A nat literal up to NAT_LITERAL_MAX expands into a Succ chain, which the -// checker unfolds in patterns and proofs; a larger one, up to the u32 bound, -// parses as U32.to_nat(n), so no chain outgrows the checker's stack. -export const NAT_LITERAL_MAX = 256; - -export function nat_to_term(n: number, s?: Span): LTerm { - if (n > NAT_LITERAL_MAX) { - return App(Ref("U32.to_nat", s), u32_to_term(n, s), s); + if (typeof t.v === "string") { + return lit_chain([...t.v].map((c) => c.codePointAt(0) as U32), t.s); } - let out: LTerm = Ctr("Zero", [], s); - for (let i = 0; i < n; i++) { - out = Ctr("Succ", [out], s); + let out: LTerm = Ctr("Zero", [], t.s); + for (let i = 0; i < t.v; i++) { + out = Ctr("Succ", [out], t.s); } return out; } +// past it, "n + T" is Nat.add(n, T) and the compiler emits U32.to_nat(n) +export const NAT_LITERAL_MAX = 256; + +// a Succ chain's count, with the literal it may end in export function nat_from_term(t: LTerm): number | null { let n = 0; while (t.$ === "Ctr" && t.k === "Succ" && t.x.length === 1) { n += 1; t = t.x[0]; } - if (t.$ === "Ctr" && t.k === "Zero" && t.x.length === 0) { - return n; - } - if (n === 0 && t.$ === "App" && t.f.$ === "Ref" && t.f.k === "U32.to_nat") { - return u32_from_term(t.x); - } - return null; + return t.$ === "Ctr" && t.k === "Zero" && t.x.length === 0 ? n + : t.$ === "Lit" && typeof t.v === "number" ? n + t.v : null; } export function u32_from_term(tm: TermOf, k: Name = "U32"): number | null { @@ -1322,11 +1315,12 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri return [xs, t]; } function term_show_sugar_nat(tm: LTerm, prc: number): string | null { + const k = nat_from_term(tm); + if (k !== null) { + return String(k) + "n"; + } const [xs, t] = term_show_chain(tm, "Succ", 1); const n = xs.length; - if (t.$ === "Ctr" && t.k === "Zero" && t.x.length === 0) { - return String(n) + "n"; - } if (n === 0) { return null; } @@ -1386,7 +1380,7 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri function term_show_sugar_str(tm: LTerm): string | null { const [cs, t] = term_show_chain(tm, "SCon", 2); const ss = cs.map((c) => term_show_sugar_chr(c, "\"")); - const tl = t.$ === "Lit" ? lit_text(t.v) + const tl = t.$ === "Lit" && typeof t.v === "string" ? lit_text(t.v) : t.$ === "Ctr" && t.k === "SNil" && t.x.length === 0 ? "" : null; if (tl === null || ss.includes(null)) { return null; @@ -1485,7 +1479,7 @@ export function term_show(term: LTerm, top: number = -1, bnd: Name[] = []): stri return tm.k + "{" + as.join(", ") + "}"; } case "Lit": { - return "\"" + lit_text(tm.v) + "\""; + return typeof tm.v === "number" ? String(tm.v) + "n" : "\"" + lit_text(tm.v) + "\""; } case "Mat": { const arms: string[] = []; @@ -1791,13 +1785,6 @@ export function parse_bind(p: Parse, t: LTerm): PVar { export function parse_patt(p: Parse, t: LTerm): Patt { const book = p.book; - const lit = t.$ === "App" ? nat_from_term(t) : null; - if (lit !== null) { - t = Ctr("Zero", [], t.s); - for (let i = 0; i < lit; i++) { - t = Ctr("Succ", [t], t.s); - } - } switch (t.$) { case "Var": { if (book_ctr(book, parse_reso(p, t.k)) !== null) { @@ -2024,7 +2011,7 @@ export function parse_term_base(p: Parse, beg: Loc): LTerm { if (k === 0 || (k & (k - 1)) !== 0) { throw Err(p.book, ctx_nil(), "a power of two count (^d takes a depth)", undefined, n.s); } - d = nat_to_term(Math.log2(k), n.s); + d = Lit(Math.log2(k), n.s); } return App(App(App(Ref("Array.new", s), T, s), d, s), xs[0], s); } @@ -2335,8 +2322,11 @@ export function parse_term_num(p: Parse): LTerm { if (parse_take(p, "+")) { let out = parse_term(p); const spn = parse_span(p, beg); + if (out.$ === "Lit" && typeof out.v === "number" && n + out.v <= 0xffffffff) { + return Lit(n + out.v, spn); + } if (n > NAT_LITERAL_MAX) { - return App(App(Ref("Nat.add", spn), nat_to_term(n, spn), spn), out, spn); + return App(App(Ref("Nat.add", spn), Lit(n, spn), spn), out, spn); } for (let i = 0; i < n; i++) { out = Ctr("Succ", [out], spn); @@ -2346,7 +2336,7 @@ export function parse_term_num(p: Parse): LTerm { if (char_is_name(parse_peek(p))) { parse_fail(p, "a nat literal (NUMBER n)"); } - return nat_to_term(n, parse_span(p, beg)); + return Lit(n, parse_span(p, beg)); } export function parse_fill(p: Parse, k: Name, xs: LTerm[], s?: Span): LTerm[] { @@ -3516,7 +3506,8 @@ export function term_infer(book: Book, lhs: LHS, tm: HTerm, qt: Quant, ctx: Ctx, // ------------------------------------------- infer-err // Γ ⊢ x : ⊥ (a goal is needed) default: { - if (tm.$ === "Ctr" && book_ctr(book, tm.k) === null) { + const t = tm.$ === "Lit" ? lit_step(tm) : tm; + if (t.$ === "Ctr" && book_ctr(book, t.k) === null) { throw Err(book, ctx, "a declared constructor", tm, tm.s, lhs.def); } throw Err(book, ctx, "an annotated term (cannot infer)", tm, tm.s, lhs.def); @@ -3627,15 +3618,17 @@ export function term_check(book: Book, lhs: LHS, tm: HTerm, qt: Quant, ty: HTerm const { xs, us } = tele_check(book, lhs, tel, tm.x, qt, ctx, d, tm.s); return Check(Ctr(tm.k, xs, tm.s), ty, us); } - // T == String, with the literal's head (SNil for "", else SCon) + // T == String (or Nat) with the literal's head: SNil or SCon (Zero or Succ) // where any other T checks the literal's first step, which reports // as the constructor it is // ----------------------------------------------------------- check-lit - // Γ ⊢ "text" : T ~ {} + // Γ ⊢ "text" : T ~ {} Γ ⊢ 3n : T ~ {} case "Lit": { const t_wnf = term_wnf(book, ty); - if (t_wnf.$ === "ADT" && t_wnf.k === "String" - && ctrs_find(book_adt(book, t_wnf, ctx, lhs.def).c, tm.v === "" ? "SNil" : "SCon") !== null) { + const [T, c] = typeof tm.v === "number" ? ["Nat", tm.v === 0 ? "Zero" : "Succ"] + : ["String", tm.v === "" ? "SNil" : "SCon"]; + if (t_wnf.$ === "ADT" && t_wnf.k === T + && ctrs_find(book_adt(book, t_wnf, ctx, lhs.def).c, c) !== null) { return Check(tm, ty, uses_nil()); } return term_check(book, lhs, term_higher(lit_step(tm)), qt, ty, ctx, d); diff --git a/bend2/comp.ts b/bend2/comp.ts index 667382d115..74be4d101c 100644 --- a/bend2/comp.ts +++ b/bend2/comp.ts @@ -786,7 +786,7 @@ function term_eta(book: Bend.Book, t: HTerm, T: HTerm, n: number): HTerm { } function term_kids(cf: Carb, tm: HTerm): HTerm[] { - const t = Bend.term_force(tm); + const t = term_lit(Bend.term_force(tm)); switch (t.$) { case "Ann": return [t.x]; case "Lam": return [term_open(t).b]; @@ -809,7 +809,7 @@ function term_kids(cf: Carb, tm: HTerm): HTerm[] { // tail position (under annotations, binders, arms and let bodies). function term_any(cf: Carb, t: HTerm, p: (s: HTerm, tail: boolean) => boolean, tail = true, seen: Set = new Set()): boolean { - const s = Bend.term_force(t); + const s = term_lit(Bend.term_force(t)); if (seen.has(s)) { return false; } @@ -830,9 +830,10 @@ function term_nodes(cf: Carb, t: HTerm): number { return n; } -// A string literal is its constructor chain to the compiler. +// A literal is its chain to the compiler; a nat past NAT_LITERAL_MAX is U32.to_nat(n). function term_lit(t: HTerm): HTerm { - return t.$ === "Lit" ? memo(LITS, t, () => Bend.term_higher(Bend.lit_full(t))) : t; + return t.$ === "Lit" ? memo(LITS, t, () => Bend.term_higher(typeof t.v === "number" && t.v > Bend.NAT_LITERAL_MAX + ? Bend.App(Bend.Ref("U32.to_nat"), Bend.u32_to_term(t.v)) : Bend.lit_full(t))) : t; } function term_const(t: HTerm): boolean { From 05ad79748fbba4e4325554a761481c2292042569 Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 21:15:25 -0300 Subject: [PATCH 7/8] Three tests pin the nat literal: its unfolds, a module's own Nat, and how it prints nat_literal_unfolds: 300n is Succ{299n} and 0n is Zero{} to a comparison, a match reads a literal pattern past 256 and a literal scrutinee, case 300n may call down(299n) (the termination check reads the literal), and a literal at the u32 bound passes through Nat.add unforced. The patterns past 256 live in laws: a compiled match on one rebuilds its scrutinee 300 deep, past clang's bracket nesting, on main as well. nat_literal_own_nat: a module's own type Nat with other constructors rejects 3n with main's exact error. nat_literal_print: a literal prints back as a literal, "n+T" past 256 is Nat.add, and a Succ chain that ends in a literal prints as one number. Co-Authored-By: Claude Fable 5.1 --- tests/check/nat_literal_own_nat.bend | 16 +++++++ tests/printer/nat_literal_print.bend | 17 +++++++ tests/proof/nat_literal_unfolds.bend | 69 ++++++++++++++++++++++++++++ 3 files changed, 102 insertions(+) create mode 100644 tests/check/nat_literal_own_nat.bend create mode 100644 tests/printer/nat_literal_print.bend create mode 100644 tests/proof/nat_literal_unfolds.bend diff --git a/tests/check/nat_literal_own_nat.bend b/tests/check/nat_literal_own_nat.bend new file mode 100644 index 0000000000..fb5dd024d9 --- /dev/null +++ b/tests/check/nat_literal_own_nat.bend @@ -0,0 +1,16 @@ +# a literal is a Nat only where Nat declares Succ and Zero: a module's +# own Nat with other constructors rejects it +type Nat is Data: + Foo{} + +def n() -> Nat: + 3n + +#|Error: +#|- expected : a declared constructor (Nat declares Foo) +#|- observed : 3n +#|Location: n +#|6 | def n() -> Nat: +#|7>| 3n +#|8 | +#|exit 1 diff --git a/tests/printer/nat_literal_print.bend b/tests/printer/nat_literal_print.bend new file mode 100644 index 0000000000..2f5e8a924d --- /dev/null +++ b/tests/printer/nat_literal_print.bend @@ -0,0 +1,17 @@ +# a nat literal prints back as a literal, a Succ chain that ends in a +# literal prints as one number, and "n + T" past 256 is Nat.add +import Base + +def small(n: Nat) -> Nat: + 2n+n + +def big(n: Nat) -> Nat: + 300n+n + +def chain() -> Nat: + Succ{Succ{300n}} + +def main(a: Nat, b: Nat) -> Nat: + Nat.add(small(a), Nat.add(big(b), Nat.add(chain(), 4294967295n))) + +#|a => b => 2n+Nat.add(a, 300n+Nat.add(b, 4294967597n)) diff --git a/tests/proof/nat_literal_unfolds.bend b/tests/proof/nat_literal_unfolds.bend new file mode 100644 index 0000000000..e4dbce4d47 --- /dev/null +++ b/tests/proof/nat_literal_unfolds.bend @@ -0,0 +1,69 @@ +# a nat literal is one Lit node in the checker; it unfolds a Succ at a +# time where a chain is read: a comparison sees 300n as Succ{299n} and +# 0n as Zero{}, a match reads a literal pattern past 256 and a literal +# scrutinee, a self-call on a smaller literal descends, and the +# evaluator steps through a literal's count. the laws hold the patterns +# past 256: a compiled match on one rebuilds its scrutinee 300 deep, +# past clang's bracket nesting. +import Base + +law big_is_succ: + {300n == Succ{299n} : Nat} + +def big_is_succ(): + {==} + +law zero_is_zero: + {0n == Zero{} : Nat} + +def zero_is_zero(): + {==} + +law add_lits: + {Nat.add(999n, 1n) == 1000n : Nat} + +def add_lits(): + {==} + +def classify(n: Nat) -> Nat: + match n: + case 300n: + 1n + case 5n: + 2n + case _: + 0n + +law classify_big: + {classify(300n) == 1n : Nat} + +def classify_big(): + {==} + +def down(n: Nat) -> Nat: + match n: + case 300n: + down(299n) + case _: + n + +law down_steps: + {down(300n) == 299n : Nat} + +def down_steps(): + {==} + +def small(n: Nat) -> Nat: + match n: + case 5n: + 2n + case _: + 0n + +def bound() -> Nat: + 4294967295n + +def main() -> List: + [small(5n), small(7n), Nat.add(299n, 1n), Nat.add(0n, bound())] + +#|[2n, 0n, 300n, 4294967295n] From 0abee8ab9c1d0dacb55ef10d201e9aa1fa58593f Mon Sep 17 00:00:00 2001 From: Matt Pereira Date: Sun, 20 Sep 2026 21:44:04 -0300 Subject: [PATCH 8/8] A run of Succ emits one overflow check of its sum, not a check per level A Succ emitted nat_chk(e, $0 + 1) around its field, so a Succ on a Succ nested the checks: a literal pattern past 256 whose default arm uses the scrutinee rebuilt it 300 levels deep, and clang refused the bracket nesting (256), on main as well. tpl_nat now reads a field that is a check of a sum, nat_chk(e, x + k) or nat_chk(x + kn), and bumps its constant: one call for the run, in C and JS. The result is the same, as nat_chk saturates (C) or throws (JS) past NAT_IMM, and x + k passes it whenever x + 1 does. Of 540 runnable tests, 10 emit differently and all print their lines. One test. bend2/comp.ts is 64998 ttok against a cap of 65000. Co-Authored-By: Claude Fable 5.1 --- bend2/comp.ts | 4 ++-- tests/compile/nat_pattern_deep.bend | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 2 deletions(-) create mode 100644 tests/compile/nat_pattern_deep.bend diff --git a/bend2/comp.ts b/bend2/comp.ts index 74be4d101c..74205fe129 100644 --- a/bend2/comp.ts +++ b/bend2/comp.ts @@ -631,7 +631,7 @@ const CYCLES: Map = new Map(); const CONSTS: Map = new Map(); -const LITS: Map = new Map(); +const LITS = new Map(); // Name // ==== @@ -681,6 +681,7 @@ function tpl(t: Gen, xs: string[]): string { function tpl_nat(u: string, f: string): Gen { return ([p]) => /^\d/.test(p) ? (BigInt(parseInt(p)) + 1n) + u + : /^nat_chk\(.* \+ \d+n?\)$/.test(p) ? p.replace(/(\d+)(n?)\)$/, (_, k, n) => `${+k + 1}${n})`) : tpl(f, [p]); } @@ -830,7 +831,6 @@ function term_nodes(cf: Carb, t: HTerm): number { return n; } -// A literal is its chain to the compiler; a nat past NAT_LITERAL_MAX is U32.to_nat(n). function term_lit(t: HTerm): HTerm { return t.$ === "Lit" ? memo(LITS, t, () => Bend.term_higher(typeof t.v === "number" && t.v > Bend.NAT_LITERAL_MAX ? Bend.App(Bend.Ref("U32.to_nat"), Bend.u32_to_term(t.v)) : Bend.lit_full(t))) : t; diff --git a/tests/compile/nat_pattern_deep.bend b/tests/compile/nat_pattern_deep.bend new file mode 100644 index 0000000000..09c9e2afdb --- /dev/null +++ b/tests/compile/nat_pattern_deep.bend @@ -0,0 +1,16 @@ +# a literal pattern past 256 whose default arm uses the scrutinee rebuilds +# it as one checked sum, nat_chk(e, x + 300), not a check per Succ: 300 +# nested calls topped clang's bracket nesting and the C lane failed +import Base + +def down(n: Nat) -> Nat: + match n: + case 300n: + down(299n) + case _: + n + +def main() -> Nat: + Nat.add(down(300n), down(7n)) + +#|306n