diff --git a/src/cast.v b/src/cast.v
index 767fe57a..b37d1987 100644
--- a/src/cast.v
+++ b/src/cast.v
@@ -3,111 +3,143 @@ module vtl
 // as_bool casts the Tensor to a Tensor of bools.
 [inline]
 pub fn (t &Tensor[T]) as_bool[T]() &Tensor[bool] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[bool](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		bool_val := td[T](val).bool()
-		ret.set(i, bool_val)
+	$if T is bool {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[bool](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			bool_val := td[T](val).bool()
+			ret.set(i, bool_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_f32 casts the Tensor to a Tensor of f32s.
 [inline]
 pub fn (t &Tensor[T]) as_f32[T]() &Tensor[f32] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[f32](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		f32_val := td[T](val).f32()
-		ret.set(i, f32_val)
+	$if T is f32 {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[f32](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			f32_val := td[T](val).f32()
+			ret.set(i, f32_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_f64 casts the Tensor to a Tensor of f64s.
 [inline]
 pub fn (t &Tensor[T]) as_f64[T]() &Tensor[f64] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[f64](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		f64_val := td[T](val).f64()
-		ret.set(i, f64_val)
+	$if T is f64 {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[f64](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			f64_val := td[T](val).f64()
+			ret.set(i, f64_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_i16 casts the Tensor to a Tensor of i16 values.
 [inline]
 pub fn (t &Tensor[T]) as_i16[T]() &Tensor[i16] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[i16](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		i16_val := td[T](val).i16()
-		ret.set(i, i16_val)
+	$if T is i16 {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[i16](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			i16_val := td[T](val).i16()
+			ret.set(i, i16_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_i8 casts the Tensor to a Tensor of i8 values.
 [inline]
 pub fn (t &Tensor[T]) as_i8[T]() &Tensor[i8] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[i8](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		i8_val := td[T](val).i8()
-		ret.set(i, i8_val)
+	$if T is i8 {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[i8](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			i8_val := td[T](val).i8()
+			ret.set(i, i8_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_int casts the Tensor to a Tensor of ints.
 [inline]
 pub fn (t &Tensor[T]) as_int[T]() &Tensor[int] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[int](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		int_val := td[T](val).int()
-		ret.set(i, int_val)
+	$if T is int {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[int](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			int_val := td[T](val).int()
+			ret.set(i, int_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_string casts the Tensor to a Tensor of string values.
 [inline]
 pub fn (t &Tensor[T]) as_string[T]() &Tensor[string] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[string](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		string_val := td[T](val).string()
-		ret.set(i, string_val)
+	$if T is string {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[string](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			string_val := td[T](val).string()
+			ret.set(i, string_val)
+		}
+		return ret
 	}
-	return ret
 }
 
 // as_u8 casts the Tensor to a Tensor of u8 values.
 [inline]
 pub fn (t &Tensor[T]) as_u8[T]() &Tensor[u8] {
-	// TODO: Implement using map
-	mut iter := t.iterator[T]()
-	mut ret := empty[u8](t.shape)
-	for {
-		val, i := iter.next() or { break }
-		u8_val := td[T](val).u8()
-		ret.set(i, u8_val)
+	$if T is u8 {
+		return t
+	} $else {
+		// TODO: Implement using map
+		mut iter := t.iterator[T]()
+		mut ret := empty[u8](t.shape)
+		for {
+			val, i := iter.next() or { break }
+			u8_val := td[T](val).u8()
+			ret.set(i, u8_val)
+		}
+		return ret
 	}
-	return ret
 }