Add smartstring default feature.

src/packages/arithmetic.rs

@@ -7,6 +7,10 @@ use crate::{def_package, EvalAltResult, Position, INT};
 #[cfg(not(feature = "no_float"))]
 use crate::FLOAT;
 
+#[cfg(feature = "no_std")]
+#[cfg(not(feature = "no_float"))]
+use num_traits::Float;
+
 #[inline(always)]
 pub fn make_err(msg: impl Into<String>) -> Box<EvalAltResult> {
     EvalAltResult::ErrorArithmetic(msg.into(), Position::NONE).into()

src/packages/math_basic.rs

@@ -12,6 +12,10 @@ use crate::result::EvalAltResult;
 #[cfg(not(feature = "no_float"))]
 use crate::stdlib::format;
 
+#[cfg(feature = "no_std")]
+#[cfg(not(feature = "no_float"))]
+use num_traits::Float;
+
 #[cfg(feature = "decimal")]
 use rust_decimal::Decimal;
 

src/packages/string_basic.rs

@@ -55,6 +55,10 @@ mod print_debug_functions {
 
     #[cfg(not(feature = "no_float"))]
     pub mod float_functions {
+        #[cfg(feature = "no_std")]
+        #[cfg(not(feature = "no_float"))]
+        use num_traits::Float;
+
         #[rhai_fn(name = "print", name = "to_string")]
         pub fn print_f64(number: f64) -> ImmutableString {
             let abs = number.abs();