✨ Add bind-style context helpers

README.md

@@ -23,6 +23,7 @@ BitLogger 是一个基于 MoonBit 编写的结构化日志库。
 - 🧱 可组合：支持 `buffered_sink(...)` 和 `filter_sink(...)`，可以在不引入复杂 runtime 的前提下组合输出策略。
 - 🔎 可复用过滤：提供 `target_has_prefix(...)`、`message_contains(...)`、`level_at_least(...)`、`field_equals(...)` 等过滤辅助函数。
 - 🩹 可变换 Record：支持 `with_patch(...)`、`patch_sink(...)` 与脱敏/补字段/message 变换 helper。
+- 🧷 可绑定上下文：支持 `bind(...)` 与 `fields(...)`，更方便地封装复用字段上下文。
 - 📮 显式队列：支持 `queued_sink(...)` / `with_queue(...)`、有界积压与溢出策略，作为后续 async sink 的 runtime-safe 基础。
 - 🧾 可配置文本格式：支持 `text_formatter(...)`、`format_text(...)`、`text_console_sink(...)`、`formatted_callback_sink(...)` 与模板化 `template` 输出。
 - 💾 Native 文件输出：支持 `file_sink(...)`，并已提供基础 size rotation / backup retention；当前仅保证 `native/llvm` backend 可用。
@@ -115,6 +116,17 @@ logger.info("login", fields=[field("user", "alice"), field("token", "secret")])
 ```
 </details>
 
+<details><summary>bind 上下文示例</summary>
+
+```moonbit
+let logger = Logger::new(console_sink(), target="audit")
+  .bind(fields([("service", "bitlogger"), ("scope", "login")]))
+
+logger.info("accepted", fields=[field("user", "alice")])
+```
+
+</details>
+
 <details><summary>显式 queue sink 示例</summary>
 
 ```moonbit

bitlogger/BitLogger_test.mbt

@@ -14,6 +14,15 @@ test "context sink merges fields" {
   logger.info("hello", fields=[field("mode", "test")])
 }
 
+test "fields helper builds field arrays ergonomically" {
+  let items = fields([("service", "bitlogger"), ("mode", "test")])
+  inspect(items.length(), content="2")
+  inspect(items[0].key, content="service")
+  inspect(items[0].value, content="bitlogger")
+  inspect(items[1].key, content="mode")
+  inspect(items[1].value, content="test")
+}
+
 test "fanout sink can write to plain and json outputs" {
   let logger = Logger::new(
     fanout_sink(console_sink(), json_console_sink()),

bitlogger/BitLogger_wbtest.mbt

@@ -259,6 +259,31 @@ test "callback sink sees child target and context logger shape" {
   inspect(captured_timestamp.val > 0UL, content="true")
 }
 
+test "bind aliases context fields ergonomically" {
+  let captured_target : Ref[String] = Ref::new("")
+  let captured_message : Ref[String] = Ref::new("")
+  let captured_fields : Ref[Array[Field]] = Ref::new([])
+  let logger = Logger::new(
+    callback_sink(fn(rec) {
+      captured_target.val = rec.target
+      captured_message.val = rec.message
+      captured_fields.val = rec.fields
+    }),
+    min_level=Level::Info,
+    target="bind",
+  ).bind(fields([("service", "bitlogger"), ("scope", "audit")]))
+  logger.info("ready", fields=[field("mode", "test")])
+  inspect(captured_target.val, content="bind")
+  inspect(captured_message.val, content="ready")
+  inspect(captured_fields.val.length(), content="3")
+  inspect(captured_fields.val[0].key, content="service")
+  inspect(captured_fields.val[0].value, content="bitlogger")
+  inspect(captured_fields.val[1].key, content="scope")
+  inspect(captured_fields.val[1].value, content="audit")
+  inspect(captured_fields.val[2].key, content="mode")
+  inspect(captured_fields.val[2].value, content="test")
+}
+
 test "buffered sink flushes manually" {
   let flushed_messages : Ref[Array[String]] = Ref::new([])
   let sink = buffered_sink(

bitlogger/README.mbt.md

@@ -36,6 +36,8 @@ BitLogger 是一个基于 MoonBit 的结构化日志库。
 - 提供 `target_has_prefix(...)`、`message_contains(...)`、`field_equals(...)` 等可复用过滤辅助函数
 - record patching via `with_patch(...)` and `patch_sink(...)`
 - 支持 `with_patch(...)`、`patch_sink(...)` 以及常见 record patch helper
+- context binding via `bind(...)` and `fields(...)`
+- 支持 `bind(...)`、`fields(...)`，更顺手地封装上下文字段
 - explicit queued delivery via `queued_sink(...)` and `with_queue(...)`
 - 支持 `queued_sink(...)`、`with_queue(...)`、有界积压与溢出策略
 - configurable text formatting via `text_formatter(...)`, `format_text(...)`, `text_console_sink(...)`, and template-driven `template` output
@@ -133,6 +135,14 @@ test {
 }
 ```
 
+```mbt check
+test {
+  let logger = Logger::new(console_sink(), target="audit")
+    .bind(fields([("service", "bitlogger"), ("scope", "login")]))
+  logger.info("accepted", fields=[field("user", "alice")])
+}
+```
+
 ```mbt check
 test {
   let logger = Logger::new(console_sink(), target="queue")

bitlogger/logger.mbt

@@ -36,6 +36,10 @@ pub fn[S] Logger::with_context_fields(self : Logger[S], fields : Array[Field]) -
   }
 }
 
+pub fn[S] Logger::bind(self : Logger[S], fields : Array[Field]) -> Logger[ContextSink[S]] {
+  self.with_context_fields(fields)
+}
+
 pub fn[S] Logger::with_filter(self : Logger[S], predicate : (Record) -> Bool) -> Logger[FilterSink[S]] {
   {
     min_level: self.min_level,

bitlogger/record.mbt

@@ -7,6 +7,12 @@ pub fn field(key : String, value : String) -> Field {
   { key, value }
 }
 
+pub fn fields(entries : Array[(String, String)]) -> Array[Field] {
+  entries.map(fn(entry) {
+    field(entry.0, entry.1)
+  })
+}
+
 pub struct Record {
   level : Level
   timestamp_ms : UInt64

docs/README-en.md

@@ -21,6 +21,7 @@ BitLogger currently provides:
 - reusable filter helpers such as `target_has_prefix(...)`, `message_contains(...)`, `level_at_least(...)`, and `field_equals(...)`
 - record patching via `with_patch(...)` and `patch_sink(...)`
 - patch helpers such as `prefix_message(...)`, `append_fields(...)`, and `redact_fields(...)`
+- context binding via `bind(...)` and `fields(...)`
 - explicit queued delivery via `queued_sink(...)` and `with_queue(...)`
 - bounded backlog with `QueueOverflowPolicy::DropNewest` and `QueueOverflowPolicy::DropOldest`
 - configurable text formatting via `text_formatter(...)`, `format_text(...)`, `text_console_sink(...)`, and template-driven `template` output
@@ -110,6 +111,15 @@ let logger = Logger::new(console_sink(), target="auth")
 logger.info("login", fields=[field("user", "alice"), field("token", "secret")])
 ```
 
+Context binding:
+
+```moonbit
+let logger = Logger::new(console_sink(), target="audit")
+  .bind(fields([("service", "bitlogger"), ("scope", "login")]))
+
+logger.info("accepted", fields=[field("user", "alice")])
+```
+
 Explicit queued sink:
 
 ```moonbit

docs/changes/0.3.0.md

@@ -30,6 +30,7 @@ version 0.3.0
 - feat: add `FileRotation`, `file_rotation(...)`, and size-based file rotation with retained backups for `file_sink(...)`
 - feat: support `sink.rotation.max_bytes` and `sink.rotation.max_backups` in JSON logger config
 - feat: add `SplitSink`, `split_sink(...)`, and `split_by_level(...)` for routing records into different sinks by predicate or level
+- feat: add `Logger::bind(...)` as an ergonomic context-binding alias and `fields(...)` helper for tuple-based field construction
 
 ### Test
 
@@ -42,6 +43,7 @@ version 0.3.0
 - test: cover template-based formatter rendering and disabled token behavior
 - test: cover file rotation config parsing, config roundtrip, and native rotation behavior
 - test: cover split sink predicate routing and level-based routing behavior
+- test: cover `bind(...)` context composition and `fields(...)` helper behavior
 - test: add async logger lifecycle, config roundtrip, and batching/flush policy test seeds
 - build: verify `bitlogger_async --target native` and `examples/async_basic --target native` compile successfully
 
@@ -55,6 +57,7 @@ version 0.3.0
 - docs: update formatter examples to demonstrate template-based text rendering
 - docs: update file sink examples to demonstrate rotation and backup retention
 - docs: add split sink examples for level-based routing
+- docs: add `bind(...)` examples for reusable context binding
 - docs: update root README and English README with async adapter notes and current scope
 - chore: ignore local `.mooncakes/` cache directory in git
 

examples/basic/main.mbt

@@ -7,6 +7,13 @@ fn main {
     .with_context_fields([@lib.field("service", "bitlogger")])
   logger.debug("custom logger ready", fields=[@lib.field("sink", "console")])
 
+  let bound_logger = @lib.Logger::new(
+    @lib.console_sink(),
+    min_level=@lib.Level::Info,
+    target="bound",
+  ).bind(@lib.fields([("service", "bitlogger"), ("scope", "audit")]))
+  bound_logger.info("bound logger ready", fields=[@lib.field("mode", "demo")])
+
   let json_logger = @lib.Logger::new(@lib.json_console_sink(), min_level=@lib.Level::Info, target="json")
   json_logger.info("json output", fields=[@lib.field("kind", "example")])