commit 181f237f4d4306b00eb10db2998c9147a9e4d120
Author: sfja <sfja2004@gmail.com>
Date:   Wed Dec 10 22:46:32 2025 +0100

    init

diff --git a/deno.jsonc b/deno.jsonc
new file mode 100644
index 0000000..2b9e474
--- /dev/null
+++ b/deno.jsonc
@@ -0,0 +1,6 @@
+{
+    "fmt": {
+        "indentWidth": 4
+    }
+}
+
diff --git a/deno.lock b/deno.lock
new file mode 100644
index 0000000..ee29d8e
--- /dev/null
+++ b/deno.lock
@@ -0,0 +1,15 @@
+{
+  "version": "5",
+  "specifiers": {
+    "jsr:@std/cli@*": "1.0.24",
+    "jsr:@std/yaml@*": "1.0.10"
+  },
+  "jsr": {
+    "@std/cli@1.0.24": {
+      "integrity": "b655a5beb26aa94f98add6bc8889f5fb9bc3ee2cc3fc954e151201f4c4200a5e"
+    },
+    "@std/yaml@1.0.10": {
+      "integrity": "245706ea3511cc50c8c6d00339c23ea2ffa27bd2c7ea5445338f8feff31fa58e"
+    }
+  }
+}
diff --git a/example.lang4 b/example.lang4
new file mode 100644
index 0000000..a656dd0
--- /dev/null
+++ b/example.lang4
@@ -0,0 +1,20 @@
+
+fn main() -> int {
+    let v: int = 123;
+    
+    let ch = 'c';
+    let s = "hello\ world";
+
+    print_int(v);
+    print_str(v);
+}
+
+
+fn print_int(v: int) {
+}
+
+fn print_str(v: str) {
+}
+
+// vim: syntax=rust
+
diff --git a/src/ast.ts b/src/ast.ts
new file mode 100644
index 0000000..79e5ac6
--- /dev/null
+++ b/src/ast.ts
@@ -0,0 +1,271 @@
+export class File {
+    constructor(
+        public readonly id: number,
+        public readonly stmts: Stmt[],
+    ) {}
+
+    visit(v: Visitor) {
+        v.visitFile?.(this);
+        this.stmts.forEach((stmt) => stmt.visit(v));
+    }
+}
+
+export class Block {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly stmts: Stmt[],
+        public readonly expr?: Expr,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitBlock?.(this) === VisitorBreak) {
+            return;
+        }
+        this.stmts.forEach((stmt) => stmt.visit(v));
+        this.expr?.visit(v);
+    }
+}
+
+export class Stmt {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly kind: StmtKind,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitStmt?.(this) === VisitorBreak) {
+            return;
+        }
+        const k = this.kind;
+        switch (k.tag) {
+            case "error":
+                break;
+            case "fn":
+                k.params.forEach((param) => param.visit(v));
+                k.retTy?.visit(v);
+                k.body.visit(v);
+                break;
+            case "let":
+                k.param.visit(v);
+                k.init.visit(v);
+                break;
+            case "assign":
+                k.place.visit(v);
+                k.expr.visit(v);
+                break;
+            case "expr":
+                k.expr.visit(v);
+                break;
+        }
+    }
+}
+
+export type StmtKind =
+    | { tag: "error" }
+    | { tag: "fn"; ident: string; params: Param[]; retTy?: Ty; body: Block }
+    | { tag: "let"; param: Param; init: Expr }
+    | { tag: "assign"; place: Expr; expr: Expr }
+    | { tag: "expr"; expr: Expr };
+
+export class Expr {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly kind: ExprKind,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitExpr?.(this) === VisitorBreak) {
+            return;
+        }
+        const k = this.kind;
+        switch (k.tag) {
+            case "error":
+                break;
+            case "ident":
+                break;
+            case "int":
+                break;
+            case "char":
+                break;
+            case "str":
+                break;
+            case "call":
+                k.expr.visit(v);
+                k.args.forEach((expr) => expr.visit(v));
+                break;
+        }
+    }
+}
+
+export type ExprKind =
+    | { tag: "error" }
+    | { tag: "ident"; ident: string }
+    | { tag: "int"; value: string }
+    | { tag: "char"; value: string }
+    | { tag: "str"; value: string }
+    | { tag: "call"; expr: Expr; args: Expr[] };
+
+export class Param {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly pat: Pat,
+        public readonly ty?: Ty,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitParam?.(this) === VisitorBreak) {
+            return;
+        }
+        this.pat.visit(v);
+        this.ty?.visit(v);
+    }
+}
+
+export class Pat {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly kind: PatKind,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitPat?.(this) === VisitorBreak) {
+            return;
+        }
+        const k = this.kind;
+        switch (k.tag) {
+            case "error":
+                break;
+            case "ident":
+                break;
+        }
+    }
+}
+
+export type PatKind =
+    | { tag: "error" }
+    | { tag: "ident"; ident: string };
+
+export class Ty {
+    constructor(
+        public readonly id: number,
+        public readonly line: number,
+        public readonly kind: TyKind,
+    ) {}
+
+    visit(v: Visitor) {
+        if (v.visitTy?.(this) === VisitorBreak) {
+            return;
+        }
+        const k = this.kind;
+        switch (k.tag) {
+            case "error":
+                break;
+            case "ident":
+                break;
+        }
+    }
+}
+
+export type TyKind =
+    | { tag: "error" }
+    | { tag: "ident"; ident: string };
+
+export const VisitorBreak = Symbol();
+export type VisitorBreak = typeof VisitorBreak;
+
+export interface Visitor {
+    visitFile?(file: File): void | VisitorBreak;
+    visitBlock?(block: Block): void | VisitorBreak;
+    visitStmt?(stmt: Stmt): void | VisitorBreak;
+    visitExpr?(expr: Expr): void | VisitorBreak;
+    visitParam?(param: Param): void | VisitorBreak;
+    visitPat?(pat: Pat): void | VisitorBreak;
+    visitTy?(ty: Ty): void | VisitorBreak;
+}
+
+export class AstBuilder {
+    private id = 0;
+
+    file(
+        stmts: Stmt[],
+    ): File {
+        return new File(
+            this.id++,
+            stmts,
+        );
+    }
+
+    block(
+        line: number,
+        stmts: Stmt[],
+        expr?: Expr,
+    ): Block {
+        return new Block(
+            this.id++,
+            line,
+            stmts,
+            expr,
+        );
+    }
+
+    stmt<Tag extends StmtKind["tag"]>(
+        line: number,
+        tag: Tag,
+        kind: Omit<StmtKind & { tag: Tag }, "tag">,
+    ): Stmt {
+        return new Stmt(
+            this.id++,
+            line,
+            { tag, ...kind } as StmtKind,
+        );
+    }
+
+    expr<Tag extends ExprKind["tag"]>(
+        line: number,
+        tag: Tag,
+        kind: Omit<StmtKind & { tag: Tag }, "tag">,
+    ): Expr {
+        return new Expr(
+            this.id++,
+            line,
+            { tag, ...kind } as ExprKind,
+        );
+    }
+
+    param(
+        line: number,
+        pat: Pat,
+        ty?: Ty,
+    ): Param {
+        return new Param(this.id++, line, pat, ty);
+    }
+
+    pat<Tag extends PatKind["tag"]>(
+        line: number,
+        tag: Tag,
+        kind: Omit<PatKind & { tag: Tag }, "tag">,
+    ): Pat {
+        return new Pat(
+            this.id++,
+            line,
+            { tag, ...kind } as PatKind,
+        );
+    }
+
+    ty<Tag extends TyKind["tag"]>(
+        line: number,
+        tag: Tag,
+        kind: Omit<TyKind & { tag: Tag }, "tag">,
+    ): Ty {
+        return new Ty(
+            this.id++,
+            line,
+            { tag, ...kind } as TyKind,
+        );
+    }
+}
diff --git a/src/main.ts b/src/main.ts
new file mode 100644
index 0000000..3c4e299
--- /dev/null
+++ b/src/main.ts
@@ -0,0 +1,22 @@
+import * as yaml from "jsr:@std/yaml";
+import { tokenize } from "./tok.ts";
+import { Parser } from "./parse.ts";
+import { Resolver } from "./resolve.ts";
+
+async function main() {
+    const text = await Deno.readTextFile(Deno.args[0]);
+    const toks = tokenize(text);
+    // console.log({ toks });
+
+    const parser = new Parser(toks);
+    const file = parser.parseFile();
+
+    // console.log(yaml.stringify({ file }, { skipInvalid: true, indent: 2 }));
+    // console.log(JSON.stringify({ file }, null, 2));
+
+    file.visit(new Resolver());
+
+    // console.log(cx);
+}
+
+await main();
diff --git a/src/parse.ts b/src/parse.ts
new file mode 100644
index 0000000..3a125e2
--- /dev/null
+++ b/src/parse.ts
@@ -0,0 +1,254 @@
+import { AstBuilder, Block, Expr, File, Param, Pat, Stmt, Ty } from "./ast.ts";
+import { Tok } from "./tok.ts";
+
+const t = new AstBuilder();
+
+export class Parser {
+    private i = 0;
+    private eaten?: Tok;
+
+    constructor(
+        private toks: Tok[],
+    ) {}
+
+    parseFile(): File {
+        const stmts: Stmt[] = [];
+        while (!this.done) {
+            stmts.push(this.parseItem());
+        }
+        return t.file(stmts);
+    }
+
+    parseItem(): Stmt {
+        const line = this.line();
+        if (this.test("fn")) {
+            return this.parseFn();
+        } else if (this.test("let")) {
+            return this.parseFn();
+        } else {
+            this.expect("item");
+            this.step();
+            return t.stmt(line, "error", {});
+        }
+    }
+
+    parseBlock(): Block {
+        const line = this.line();
+        this.step();
+
+        const stmts: Stmt[] = [];
+        let expr: Expr | undefined = undefined;
+
+        while (!this.done && !this.test("}")) {
+            const line = this.line();
+            if (this.test("fn")) {
+                stmts.push(this.parseFn());
+            } else if (this.test("let")) {
+                stmts.push(this.parseLet());
+                this.expect(";");
+            } else {
+                const lhs = this.parseExpr();
+                if (this.eat("=")) {
+                    const rhs = this.parseExpr();
+                    this.expect(";");
+                    stmts.push(
+                        t.stmt(line, "assign", { place: lhs, expr: rhs }),
+                    );
+                } else if (this.eat(";")) {
+                    stmts.push(t.stmt(line, "expr", { expr: lhs }));
+                } else if (this.test("}")) {
+                    expr = lhs;
+                    break;
+                } else {
+                    this.expect(";");
+                }
+            }
+        }
+
+        this.expect("}");
+        return t.block(line, stmts, expr);
+    }
+
+    parseFn(): Stmt {
+        const line = this.line();
+        this.step();
+        if (!this.expect("ident")) {
+            return t.stmt(line, "error", {});
+        }
+        const ident = this.eaten!.value!;
+        const params: Param[] = [];
+        if (!this.expect("(")) {
+            return t.stmt(line, "error", {});
+        }
+        if (!this.done && !this.test(")")) {
+            params.push(this.parseParam());
+            while (this.eat(",")) {
+                if (this.done || this.test(")")) {
+                    break;
+                }
+                params.push(this.parseParam());
+            }
+        }
+        if (!this.expect(")")) {
+            return t.stmt(line, "error", {});
+        }
+        let retTy: Ty | undefined = undefined;
+        if (this.eat("->")) {
+            retTy = this.parseTy();
+        }
+        if (!this.test("{")) {
+            this.expect("{");
+            return t.stmt(line, "error", {});
+        }
+        const body = this.parseBlock();
+        return t.stmt(line, "fn", { ident, params, retTy, body });
+    }
+
+    parseLet(): Stmt {
+        const line = this.line();
+        this.step();
+        const param = this.parseParam();
+        if (!this.expect("=")) {
+            return t.stmt(line, "error", {});
+        }
+        const init = this.parseExpr();
+        return t.stmt(line, "let", { param, init });
+    }
+
+    parseExpr(): Expr {
+        return this.parsePostfix();
+    }
+
+    parsePostfix(): Expr {
+        let expr = this.parseOp();
+        while (true) {
+            const line = this.line();
+            if (this.eat("(")) {
+                const args: Expr[] = [];
+                if (!this.done && !this.test(")")) {
+                    args.push(this.parseExpr());
+                    while (this.eat(",")) {
+                        if (this.done || this.test(")")) {
+                            break;
+                        }
+                        args.push(this.parseExpr());
+                    }
+                }
+                if (!this.expect(")")) {
+                    return t.expr(line, "error", {});
+                }
+                expr = t.expr(line, "call", { expr, args });
+            } else {
+                break;
+            }
+        }
+        return expr;
+    }
+
+    parseOp(): Expr {
+        const line = this.line();
+        if (this.eat("ident")) {
+            const ident = this.eaten!.value!;
+            return t.expr(line, "ident", { ident });
+        } else if (this.eat("int")) {
+            const value = this.eaten!.value!;
+            return t.expr(line, "int", { value });
+        } else if (this.eat("char")) {
+            const value = this.eaten!.value!;
+            return t.expr(line, "int", { value });
+        } else if (this.eat("str")) {
+            const value = this.eaten!.value!;
+            return t.expr(line, "int", { value });
+        } else {
+            this.expect("expr");
+            this.step();
+            return t.expr(line, "error", {});
+        }
+    }
+
+    parseParam(): Param {
+        const line = this.line();
+        const pat = this.parsePat();
+        let ty: Ty | undefined = undefined;
+        if (this.eat(":")) {
+            ty = this.parseTy();
+        }
+        return t.param(line, pat, ty);
+    }
+
+    parsePat(): Pat {
+        const line = this.line();
+        if (this.eat("ident")) {
+            const ident = this.eaten!.value!;
+            return t.pat(line, "ident", { ident });
+        } else {
+            this.expect("pat");
+            this.step();
+            return t.pat(line, "error", {});
+        }
+    }
+
+    parseTy(): Ty {
+        const line = this.line();
+        if (this.eat("ident")) {
+            const ident = this.eaten!.value!;
+            return t.ty(line, "ident", { ident });
+        } else {
+            this.expect("ty");
+            this.step();
+            return t.ty(line, "error", {});
+        }
+    }
+
+    private expect(type: string): boolean {
+        const line = this.line();
+        if (!this.eat(type)) {
+            if (this.done) {
+                this.error(line, `expected '${type}', got 'eof'`);
+            } else {
+                this.error(line, `expected '${type}', got '${this.tok.type}'`);
+            }
+            return false;
+        }
+        return true;
+    }
+
+    private eat(type: string): boolean {
+        if (this.test(type)) {
+            this.eaten = this.tok;
+            this.step();
+            return true;
+        }
+        return false;
+    }
+
+    private test(type: string): boolean {
+        return !this.done && this.tok.type === type;
+    }
+
+    private step() {
+        this.i += 1;
+    }
+
+    private line(): number {
+        return this.tok.line;
+    }
+
+    private get tok(): Tok {
+        return this.toks[this.i];
+    }
+
+    private get done(): boolean {
+        return this.i >= this.toks.length;
+    }
+
+    private error(line: number, message: string) {
+        console.error(
+            `%cerror%c: ${message}\n %c--> line ${line}%c`,
+            "font-weight: bold; color: red",
+            "font-weight: bold; color: while",
+            "color: cyan",
+            "",
+        );
+    }
+}
diff --git a/src/resolve.ts b/src/resolve.ts
new file mode 100644
index 0000000..621858c
--- /dev/null
+++ b/src/resolve.ts
@@ -0,0 +1,81 @@
+import { Pat, Stmt, Visitor, VisitorBreak } from "./ast.ts";
+
+export class Def {
+    constructor(
+        kind: DefKind,
+    ) {}
+}
+
+export type DefKind =
+    | { tag: "fn"; stmt: Stmt }
+    | { tag: "param"; stmt: Stmt; pat: Pat }
+    | { tag: "let"; stmt: Stmt; pat: Pat };
+
+export class Rib {
+    private syms = new Map<string, Def>();
+
+    constructor(
+        private kind: RibKind,
+    ) {}
+
+    define(ident: string, def: Def) {
+        this.syms.set(ident, def);
+    }
+}
+
+export type RibKind =
+    | { tag: "root" }
+    | { tag: "fn"; parent: Rib }
+    | { tag: "block"; parent: Rib }
+    | { tag: "let"; parent: Rib };
+
+export class Resolver implements Visitor {
+    private rib = new Rib({ tag: "root" });
+    private ribStateStack: Rib[] = [];
+
+    pushRib<Tag extends RibKind["tag"]>(
+        tag: Tag,
+        kind: Omit<RibKind & { tag: Tag }, "tag" | "parent">,
+    ) {
+        this.rib = new Rib({ tag, parent: this.rib, ...kind } as RibKind);
+    }
+
+    saveRibState() {
+        this.ribStateStack.push(this.rib);
+    }
+
+    restoreRibState() {
+        this.rib = this.ribStateStack.pop()!;
+    }
+
+    define(ident: string, def: Def) {
+        this.rib.define(ident, def);
+    }
+
+    visitStmt(stmt: Stmt): void | VisitorBreak {
+        const k = stmt.kind;
+        if (k.tag === "fn") {
+            this.define(k.ident, new Def({ tag: "fn", stmt }));
+            this.saveRibState();
+            this.pushRib("fn", {});
+            k.params.forEach((param) => param.visit(this));
+            k.retTy?.visit(this);
+            k.body.visit(this);
+            this.restoreRibState();
+            return VisitorBreak;
+        } else if (k.tag === "let") {
+            this.pushRib("let", {});
+            k.param.pat.visit({
+                visitPat: (pat: Pat) => {
+                    const k = pat.kind;
+                    if (k.tag === "ident") {
+                        this.define(
+                            k.ident,
+                            new Def({ tag: "let", stmt, pat }),
+                        );
+                    }
+                },
+            });
+        }
+    }
+}
diff --git a/src/tok.ts b/src/tok.ts
new file mode 100644
index 0000000..3baeccf
--- /dev/null
+++ b/src/tok.ts
@@ -0,0 +1,77 @@
+export type Tok = {
+    type: string;
+    line: number;
+    value?: string;
+};
+
+const keywords = new Set([
+    "fn",
+    "let",
+    "true",
+    "false",
+]);
+
+type OpTree = Map<string, OpTree | null>;
+const opTreeRoot: OpTree = new Map(
+    Object.entries({
+        "-": new Map(Object.entries({
+            ">": null,
+        })),
+    }),
+);
+
+export function tokenize(text: string): Tok[] {
+    return text
+        .replace(/\/\/[^\n]*/g, "")
+        .replace(/\/\*.*?\*\//gs, "")
+        .replace(/([^a-zA-Z0-9_'"\\ \t\r])/g, " $1 ")
+        .split(/(?<!\\)[ \t\r]/)
+        .filter((tok) => tok !== "")
+        .map((tok) => tok.replace(/\\ /g, " "))
+        .reduce<[string[], OpTree]>(([toks, opTree], tok) => {
+            if (toks.length === 0) {
+                toks.push(tok);
+                return [toks, opTree];
+            }
+            const last = toks.at(-1)!;
+            if (!opTree.has(last)) {
+                toks.push(tok);
+                return [toks, opTreeRoot];
+            }
+            if (opTree.get(last) === null) {
+                toks.push(tok);
+                return [toks, opTreeRoot];
+            } else if (opTree.get(last)!.has(tok)) {
+                toks[toks.length - 1] += tok;
+                return [toks, opTree.get(last)!];
+            } else {
+                toks.push(tok);
+                return [toks, opTreeRoot];
+            }
+        }, [[], opTreeRoot])[0]
+        .slice(0, -1)
+        .reduce<[Tok[], number]>(([toks, line], type) => {
+            if (type === "\n") {
+                return [toks, line + 1];
+            } else {
+                toks.push({ type, line });
+                return [toks, line];
+            }
+        }, [[], 1])[0]
+        .map((tok) => {
+            if (
+                /^[a-zA-Z_][a-zA-Z0-9_]*$/.test(tok.type) &&
+                !keywords.has(tok.type)
+            ) {
+                return { type: "ident", line: tok.line, value: tok.type };
+            } else if (/^[0-9_]+$/.test(tok.type)) {
+                return { type: "int", line: tok.line, value: tok.type };
+            } else if (/^'.*?'$/.test(tok.type)) {
+                return { type: "char", line: tok.line, value: tok.type };
+            } else if (/^".*?"$/.test(tok.type)) {
+                return { type: "str", line: tok.line, value: tok.type };
+            } else {
+                return tok;
+            }
+        });
+}