ARROW-9088: [Rust] Make prettyprint optional

rust/arrow/Cargo.toml

@@ -50,12 +50,13 @@ chrono = "0.4"
 flatbuffers = "0.6"
 hex = "0.4"
 arrow-flight = { path = "../arrow-flight", optional = true }
-prettytable-rs = "0.8.0"
+prettytable-rs = { version = "0.8.0", optional = true }
 
 [features]
 simd = ["packed_simd"]
 flight = ["arrow-flight"]
-default = ["flight"]
+prettyprint = ["prettytable-rs"]
+default = ["flight", "prettyprint"]
 
 [dev-dependencies]
 criterion = "0.3"

rust/arrow/README.md

@@ -67,13 +67,25 @@ The above script will run the `flatc` compiler and perform some adjustments to t
 ## SIMD (Single Instruction Multiple Data)
 
 Arrow uses the [packed_simd](https://crates.io/crates/packed_simd) crate to optimize many of the implementations in the
-[compute](https://github.com/apache/arrow/tree/master/rust/arrow/src/compute) module using SIMD intrinsics.  These
-optimizations are enabled by the `simd` feature flag and are turned on by default, but can be disabled, for example:
+[compute](https://github.com/apache/arrow/tree/master/rust/arrow/src/compute) module using SIMD intrinsics. 
+These optimizations are enabled by the `simd` feature flag and are turned on by default, but can be disabled, for example:
 
 ```bash
 cargo build --no-default-features
 ```
 
+For more features, see the Features heading below.
+
+## Features
+
+Arrow uses the following features:
+
+* `simd`
+* `flight` which contains useful functions to convert between the Flight wire format and Arrow data
+* `prettyprint` which is a utility for printing record batches
+
+`simd` is current disabled by default, while the other features are enabled by default. Disabling `prettyprint` might be necessary in order to compile Arrow to the `wasm32-unknown-unknown` WASM target.
+
 # Publishing to crates.io
 
 An Arrow committer can publish this crate after an official project release has

rust/arrow/examples/read_csv.rs

@@ -23,6 +23,7 @@ use std::sync::Arc;
 use arrow::csv;
 use arrow::datatypes::{DataType, Field, Schema};
 use arrow::error::Result;
+#[cfg(feature = "prettyprint")]
 use arrow::util::pretty::print_batches;
 
 fn main() -> Result<()> {
@@ -35,6 +36,10 @@ fn main() -> Result<()> {
     let file = File::open("test/data/uk_cities.csv").unwrap();
 
     let mut csv = csv::Reader::new(file, Arc::new(schema), false, None, 1024, None);
-    let batch = csv.next().unwrap().unwrap();
-    print_batches(&vec![batch])
+    let _batch = csv.next().unwrap().unwrap();
+    #[cfg(feature = "prettyprint")]
+    {
+        print_batches(&vec![_batch]).unwrap();
+    }
+    Ok(())
 }

rust/arrow/examples/read_csv_infer_schema.rs

@@ -19,6 +19,7 @@ extern crate arrow;
 
 use arrow::csv;
 use arrow::error::Result;
+#[cfg(feature = "prettyprint")]
 use arrow::util::pretty::print_batches;
 use std::fs::File;
 
@@ -28,7 +29,10 @@ fn main() -> Result<()> {
         .has_header(true)
         .infer_schema(Some(100));
     let mut csv = builder.build(file).unwrap();
-    let batch = csv.next().unwrap().unwrap();
-
-    print_batches(&vec![batch])
+    let _batch = csv.next().unwrap().unwrap();
+    #[cfg(feature = "prettyprint")]
+    {
+        print_batches(&vec![_batch]).unwrap();
+    }
+    Ok(())
 }

rust/arrow/src/util/mod.rs

@@ -17,6 +17,7 @@
 
 pub mod bit_util;
 pub mod integration_util;
+#[cfg(feature = "prettyprint")]
 pub mod pretty;
 pub mod string_writer;
 pub mod test_util;