Add ArgFloatLike.

vm/src/function/numlike.rs

@@ -22,3 +22,32 @@ impl TryFromObject for ArgComplexLike {
         Ok(ArgComplexLike { value })
     }
 }
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+#[repr(transparent)]
+pub struct ArgFloatLike {
+    value: f64,
+}
+
+impl ArgFloatLike {
+    pub fn to_f64(self) -> f64 {
+        self.value
+    }
+
+    pub fn vec_into_f64(v: Vec<Self>) -> Vec<f64> {
+        // TODO: Vec::into_raw_parts once stabilized
+        let mut v = std::mem::ManuallyDrop::new(v);
+        let (p, l, c) = (v.as_mut_ptr(), v.len(), v.capacity());
+        // SAFETY: IntoPyFloat is repr(transparent) over f64
+        unsafe { Vec::from_raw_parts(p.cast(), l, c) }
+    }
+}
+
+impl TryFromObject for ArgFloatLike {
+    fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
+        let value = obj.try_to_f64(vm)?.ok_or_else(|| {
+            vm.new_type_error(format!("must be real number, not {}", obj.class().name()))
+        })?;
+        Ok(ArgFloatLike { value })
+    }
+}