Redesign the features

Cargo.toml

@@ -24,10 +24,11 @@ keywords = ["beta", "error", "gamma"]
 
 [features]
 default = ["no_std"]
-no_std = []
+no_std = ["lambert_w/libm"]
+std = ["lambert_w/std"]
 
 [dependencies]
-lambert_w = { version = "0.5.2", default-features = false, features = ["50bits", "libm"] }
+lambert_w = { version = "0.5.2", default-features = false, features = ["50bits"] }
 libm = "0.2"
 
 [dev-dependencies]

Makefile

@@ -3,16 +3,16 @@ all: check test
 
 .PHONY: test
 bench:
-	cargo +nightly bench
-	cargo +nightly bench --no-default-features
+	cargo +nightly bench --no-default-features --features no_std
+	cargo +nightly bench --no-default-features --features std
 
 .PHONY: check
 check:
-	cargo clippy -- -D warnings
-	cargo clippy --no-default-features -- -D warnings
+	cargo clippy --no-default-features --features no_std -- -D warnings
+	cargo clippy --no-default-features --features std -- -D warnings
 	cargo fmt --all -- --check
 
 .PHONY: test
 test:
-	cargo test
-	cargo test --no-default-features
+	cargo test --no-default-features --features no_std
+	cargo test --no-default-features --features std

src/primitive/mod.rs

@@ -28,8 +28,12 @@ macro_rules! implement {
     }
 }
 
-#[cfg_attr(feature = "no_std", path = "extrinsic.rs")]
-#[cfg_attr(not(feature = "no_std"), path = "intrinsic.rs")]
+#[cfg(feature = "no_std")]
+#[path = "extrinsic.rs"]
+mod implementation;
+
+#[cfg(feature = "std")]
+#[path = "intrinsic.rs"]
 mod implementation;
 
 pub use implementation::Primitive;