Add README

README.md

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+crates/datapath/README.md

crates/datapath/README.md

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+# Datapath: type-safe structured paths
+
+Provides simple macros and utilities for type-safe structured paths.
+This is intended for use with S3 and [duckdb hive partitions](https://duckdb.org/docs/stable/data/partitioning/hive_partitioning), or simple S3 paths for [lancedb](https://lancedb.com).
+
+
+## Basic Usage
+
+```rust
+use datapath::{datapath, Datapath};
+use uuid::Uuid;
+
+/// Define a datapath pattern
+datapath! {
+    struct CaptureRaw(capture/user_id=Uuid/ts=i64/raw/2.0);
+}
+
+// Create a datapath instance
+let path = CaptureRaw {
+    user_id: Uuid::new_v4(),
+    ts: 1234567890,
+};
+
+println!("{}", path); // "capture/user_id=<uuid>/ts=1234567890/raw/2.0"
+
+let file = path.with_file("data.json");
+println!("{}", file); // "capture/user_id=<uuid>/ts=1234567890/raw/2.0/data.json"
+
+let parsed = CaptureRaw::parse("capture/user_id=550e8400-e29b-41d4-a716-446655440000/ts=1234567890/raw/2.0/data.json");
+match parsed {
+    Some(datapath_file) => {
+        println!("User ID: {}", datapath_file.path.user_id);
+        println!("Timestamp: {}", datapath_file.path.ts);
+        println!("File: {}", datapath_file.file);
+    }
+    None => println!("Invalid path format"),
+}
+```
+
+## Schema Associations
+
+Associate datapaths with schema types for type-safe data handling:
+
+```rust
+use datapath::datapath;
+
+pub struct UserEvent {
+    pub action: String,
+    pub timestamp: i64,
+}
+
+datapath! {
+    struct EventPath {
+        pattern: events/user_id=String/date=i64/"v1.0"
+        schema: UserEvent
+    };
+}
+
+// EventPath now implements SchemaDatapath
+// EventPath::Schema == UserEvent
+```
+
+## Examples
+
+```rust
+use datapath::datapath;
+
+pub struct MetricsSchema;
+
+datapath! {
+    // Constant segments (identifiers)
+    struct SimplePath(data/logs/events);
+
+    // String literal constants (for segments with dashes)
+    struct QuotedPath("web-data"/"user-logs"/2024);
+
+    // Typed partitions with identifier keys
+    struct TypedPath(domain/user_id=uuid::Uuid/timestamp=i64);
+
+    // Typed partitions with dashes
+    struct QuotedKeys("service-name"=String/"request-id"=uuid::Uuid);
+
+    // With schema association
+    struct MetricsData {
+        pattern: metrics/service=String/timestamp=i64/"v1.0"
+        schema: MetricsSchema
+    };
+}
+```

crates/datapath/src/lib.rs

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+// this readme is symlinked to the root of the repo,
+// because cargo publish does odd things with paths.
+// a relative path to the root readme will NOT work.
+#![doc = include_str!("../README.md")]
+
 // silence linter, used in README
 #[cfg(test)]
 use uuid as _;