Use impl Iterator in arguments

This is functionally almost identical, but it is a bit easier to read.
For more details, see:
<https://doc.rust-lang.org/nightly/edition-guide/rust-2018/trait-system/impl-trait-for-returning-complex-types-with-ease.html#argument-position>

Author: GrantM11235

i2c/src/lib.rs

@@ -31,10 +31,11 @@ where
         self.i2c
     }
 
-    fn send_iter<I>(&mut self, first_byte: u8, data: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = u8>,
-    {
+    fn send_iter(
+        &mut self,
+        first_byte: u8,
+        data: impl Iterator<Item = u8>,
+    ) -> Result<(), DisplayError> {
         let mut writebuf = [0; 17];
         let mut i = 1;
         let len = writebuf.len();
@@ -71,18 +72,18 @@ where
     type Word = u8;
 
     #[inline]
-    fn send_command_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_command_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         self.send_iter(0, iter)
     }
 
     #[inline]
-    fn send_data_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_data_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         self.send_iter(self.data_byte, iter)
     }
 }

parallel-gpio/src/lib.rs

@@ -195,19 +195,19 @@ where
 {
     type Word = u8;
 
-    fn send_command_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_command_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         self.dc.set_low().map_err(|_| DisplayError::DCError)?;
 
         self.send_iter(iter)
     }
 
-    fn send_data_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_data_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         self.dc.set_high().map_err(|_| DisplayError::DCError)?;
 
         self.send_iter(iter)

spi/src/lib.rs

@@ -7,9 +7,9 @@ use hal::digital::v2::OutputPin;
 
 use display_interface::{DisplayError, WriteOnlyDataCommand};
 
-fn send_iter<SPI: hal::blocking::spi::Write<u8>, I: Iterator<Item = u8>>(
-    spi: &mut SPI,
-    iter: I,
+fn send_iter(
+    spi: &mut impl hal::blocking::spi::Write<u8>,
+    iter: impl Iterator<Item = u8>,
 ) -> Result<(), DisplayError> {
     let mut buf = [0; 32];
     let mut i = 0;
@@ -68,10 +68,10 @@ where
     type Word = u8;
 
     #[inline]
-    fn send_command_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_command_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         // Assert chip select pin
         self.cs.set_low().map_err(|_| DisplayError::CSError)?;
 
@@ -88,10 +88,10 @@ where
     }
 
     #[inline]
-    fn send_data_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_data_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         // Assert chip select pin
         self.cs.set_low().map_err(|_| DisplayError::CSError)?;
 
@@ -181,10 +181,10 @@ where
     type Word = u8;
 
     #[inline]
-    fn send_command_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_command_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         // 1 = data, 0 = command
         self.dc.set_low().map_err(|_| DisplayError::DCError)?;
 
@@ -193,10 +193,10 @@ where
     }
 
     #[inline]
-    fn send_data_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>,
-    {
+    fn send_data_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError> {
         // 1 = data, 0 = command
         self.dc.set_high().map_err(|_| DisplayError::DCError)?;
 

src/lib.rs

@@ -32,13 +32,15 @@ pub enum DisplayError {
 pub trait WriteOnlyDataCommand {
     type Word: Copy;
 
-    fn send_command_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>;
-
-    fn send_data_iter<I>(&mut self, iter: I) -> Result<(), DisplayError>
-    where
-        I: Iterator<Item = Self::Word>;
+    fn send_command_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError>;
+
+    fn send_data_iter(
+        &mut self,
+        iter: impl Iterator<Item = Self::Word>,
+    ) -> Result<(), DisplayError>;
 
     #[inline]
     fn send_command_slice(&mut self, slice: &[Self::Word]) -> Result<(), DisplayError> {