Some small refactors of constant functions

therm_util/src/reader.rs

@@ -6,14 +6,13 @@ pub struct ByteReader<Rd> {
     bytes: Rd,
 }
 
-const MK_OK: &'static Fn(io::Result<u8>) -> Option<u8> = &|s| s.ok();
-
 impl<R: io::Read>
     ByteReader<iter::FilterMap<io::Bytes<R>,
                                &'static Fn(io::Result<u8>) -> Option<u8>>>
 {
     /// Create a ByteReader from any type that implement Read
     pub fn from_reader(r: R) -> Self {
+        const MK_OK: &'static Fn(io::Result<u8>) -> Option<u8> = &io::Result::<u8>::ok;
         let bytes = r.bytes().filter_map(MK_OK);
         ByteReader { bytes: bytes }
     }
@@ -36,11 +35,10 @@ impl ByteReader<vec::IntoIter<u8>> {
     }
 }
 
-const DEREF: &'static Fn(&u8) -> u8 = &|s| *s;
-
 impl<'a> ByteReader<iter::Map<slice::Iter<'a, u8>, &'static Fn(&u8) -> u8>> {
     /// Create a reader from a borrowed slice, with a copy on each access
     pub fn from_slice(lst: &'a [u8]) -> Self {
+        const DEREF: &'static Fn(&u8) -> u8 = &|s| *s;
         ByteReader { bytes: lst.iter().map(DEREF) }
     }
 }