feat: Implement print without newline (#3650)

# Description

## Problem\*

Resolves  **#3575
Resolves **#2912 (duplicate)

Continuation of #3576
## Summary\*

Refactors `println_oracle` method into `print` with boolean indicator,
allowing `print` to coexist with `println` under the same `ForeignCall`
string symbol.
Updates appropriate tests, and logging.md documentation.
Add a subchapter to `03_string.md` documentation for the `fmtstr` type

## Additional Context



## Documentation\*

Check one:
- [ ] No documentation needed.
- [x] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: jfecher <[email protected]>

compiler/noirc_frontend/src/monomorphization/mod.rs

@@ -889,10 +889,11 @@ impl<'interner> Monomorphizer<'interner> {
 
         if let ast::Expression::Ident(ident) = original_func.as_ref() {
             if let Definition::Oracle(name) = &ident.definition {
-                if name.as_str() == "println" {
+                if name.as_str() == "print" {
                     // Oracle calls are required to be wrapped in an unconstrained function
-                    // Thus, the only argument to the `println` oracle is expected to always be an ident
-                    self.append_printable_type_info(&hir_arguments[0], &mut arguments);
+                    // The first argument to the `print` oracle is a bool, indicating a newline to be inserted at the end of the input
+                    // The second argument is expected to always be an ident
+                    self.append_printable_type_info(&hir_arguments[1], &mut arguments);
                 }
             }
         }

docs/docs/standard_library/logging.md

@@ -7,6 +7,7 @@ keywords:
   [
     noir logging,
     println statement,
+    print statement,
     debugging in noir,
     noir std library,
     logging tutorial,
@@ -17,14 +18,13 @@ keywords:
   ]
 ---
 
-The standard library provides a familiar `println` statement you can use. Despite being a limited
-implementation of rust's `println!` macro, this construct can be useful for debugging.
+The standard library provides two familiar statements you can use: `println` and `print`. Despite being a limited implementation of rust's `println!` and `print!` macros, these constructs can be useful for debugging.
 
-You can print the output of println statements in your Noir code by using the `nargo execute` command or the `--show-output` flag when using `nargo test` (provided there are println statements in your tests).
+You can print the output of both statements in your Noir code by using the `nargo execute` command or the `--show-output` flag when using `nargo test` (provided there are print statements in your tests).
 
-It is recommended to use `nargo execute` if you want to debug failing constrains with `println` statements. This is due to every input in a test being a constant rather than a witness, so we issue an error during compilation while we only print during execution (which comes after compilation). `println` will not work for failed constraints caught at compile time.
+It is recommended to use `nargo execute` if you want to debug failing constrains with `println` or `print` statements. This is due to every input in a test being a constant rather than a witness, so we issue an error during compilation while we only print during execution (which comes after compilation). Neither `println`, nor `print` are callable for failed constraints caught at compile time.
 
-The `println` statement is unconstrained, so it works for outputting integers, fields, strings, and even structs or expressions. For example:
+Both `print` and `println` are generic functions which can work on integers, fields, strings, and even structs or expressions. Note however, that slices are currently unsupported. For example:
 
 ```rust
 use dep::std;
@@ -40,10 +40,9 @@ fn main(age : Field, height : Field) {
     std::println(age + height);
     std::println("Hello world!");
 }
-
 ```
 
-You can print multiple different types in the same statement and string as well as a new "fmtstr" type. A `fmtstr` can be specified in the same way as a normal string it just should be prepended with an "f" character:
+You can print different types in the same statement (including strings) with a type called `fmtstr`. It can be specified in the same way as a normal string, just prepended with an "f" character:
 
 ```rust
   let fmt_str = f"i: {i}, j: {j}";
@@ -59,4 +58,20 @@ You can print multiple different types in the same statement and string as well
 
   let foo = fooStruct { my_struct: s, foo: 15 };
   std::println(f"s: {s}, foo: {foo}");
+
+  std::println(15);       // prints 0x0f, implicit Field
+  std::println(-1 as u8); // prints 255
+  std::println(-1 as i8); // prints -1
+```
+
+Examples shown above are interchangeable between the two `print` statements:
+
+```rust
+let person = Person { age : age, height : height };
+
+std::println(person);
+std::print(person);
+
+std::println("Hello world!"); // Prints with a newline at the end of the input
+std::print("Hello world!");   // Prints the input and keeps cursor on the same line
 ```

docs/versioned_docs/version-v0.19.4/language_concepts/data_types/03_strings.md

@@ -15,8 +15,7 @@ keywords:
 
 The string type is a fixed length value defined with `str<N>`.
 
-You can use strings in `assert()` functions or print them with
-`std::println()`. See more about [Logging](../../standard_library/logging).
+You can use strings in `assert()` functions or print them with `std::println()`. See more about [Logging](../../standard_library/logging).
 
 ```rust
 use dep::std;
@@ -42,7 +41,7 @@ fn main() {
 }
 ```
 
-## Escape characters
+## Escape Characters
 
 You can use escape characters for your strings:
 
@@ -58,6 +57,32 @@ You can use escape characters for your strings:
 Example:
 
 ```rust
-let s = "Hello \"world" // prints "Hello "world"
+let s = "Hello \"world"; // prints "Hello "world"
 let s = "hey \tyou"; // prints "hey   you"
 ```
+
+## Formatted Strings
+
+You can prepend a string with the singular `f` token to create a formatted string. This is useful when logging, as it allows injection of local variables:
+
+```rust
+let var = 15;
+std::println(f"var {var}") // prints "var 0x0F"
+
+let var = -1 as u8;
+std::println(f"var {var}") // prints "var 255"
+
+let var : i8 = -1;
+std::println(f"var {var}") // prints "var -1"
+
+// prints "Hello
+//world"
+std::println(f"Hello
+world");
+
+std::println(f"hey \tyou"); // prints "hey \tyou"
+```
+
+A type can be specified to print numbers either as hex via `Field`, unsigned via `u*` types and signed via `i*` types.
+
+Note that escaped characters in formatted strings `fmtstr` will be outputted as defined, i.e. "\n" will be printed `\n`, not as a new line. You can add a newline or other whitespace by creating a multiline string as in the example above.

noir_stdlib/src/lib.nr

@@ -20,12 +20,16 @@ mod option;
 mod string;
 mod test;
 // Oracle calls are required to be wrapped in an unconstrained function
-// Thus, the only argument to the `println` oracle is expected to always be an ident 
-#[oracle(println)]
-unconstrained fn println_oracle<T>(_input: T) {}
+// Thus, the only argument to the `println` oracle is expected to always be an ident
+#[oracle(print)]
+unconstrained fn print_oracle<T>(_with_newline: bool, _input: T) {}
+
+unconstrained pub fn print<T>(input: T) {
+    print_oracle(false, input);
+}
 
 unconstrained pub fn println<T>(input: T) {
-    println_oracle(input);
+    print_oracle(true, input);
 }
 
 #[foreign(recursive_aggregation)]

test_programs/execution_success/strings/src/main.nr

@@ -10,20 +10,26 @@ fn main(message: pub str<11>, y: Field, hex_as_string: str<4>, hex_as_field: Fie
     let x = 10;
     let z = x * 5;
     std::println(10);
+    std::print(10);
 
     std::println(z); // x * 5 in println not yet supported
+    std::print(z);
     std::println(x);
+    std::print(x);
 
     let array = [1, 2, 3, 5, 8];
     assert(y == 5); // Change to y != 5 to see how the later print statements are not called
     std::println(array);
+    std::print(array);
 
     bad_message = "hell\0\"world";
     std::println(bad_message);
+    std::print(bad_message);
     assert(message != bad_message);
 
     let hash = std::hash::pedersen_commitment([x]);
     std::println(hash);
+    std::print(hash);
 
     assert(hex_as_string == "0x41");
     // assert(hex_as_string != 0x41); This will fail with a type mismatch between str[4] and Field
@@ -36,6 +42,10 @@ fn test_prints_strings() {
 
     std::println(message);
     std::println("goodbye world");
+
+    std::print(message);
+    std::print("\n");
+    std::print("goodbye world\n");
 }
 
 #[test]
@@ -52,8 +62,6 @@ fn test_prints_array() {
 }
 
 fn failed_constraint(hex_as_field: Field) {
-    // TODO(#2116): Note that `println` will not work if a failed constraint can be 
-    // evaluated at compile time. 
     // When this method is called from a test method or with constant values
     // a `Failed constraint` compile error will be caught before this `println`
     // is executed as the input will be a constant.

tooling/nargo/src/ops/foreign_calls.rs

@@ -14,7 +14,7 @@ pub trait ForeignCallExecutor {
 /// This enumeration represents the Brillig foreign calls that are natively supported by nargo.
 /// After resolution of a foreign call, nargo will restart execution of the ACVM
 pub(crate) enum ForeignCall {
-    Println,
+    Print,
     CreateMock,
     SetMockParams,
     SetMockReturns,
@@ -31,7 +31,7 @@ impl std::fmt::Display for ForeignCall {
 impl ForeignCall {
     pub(crate) fn name(&self) -> &'static str {
         match self {
-            ForeignCall::Println => "println",
+            ForeignCall::Print => "print",
             ForeignCall::CreateMock => "create_mock",
             ForeignCall::SetMockParams => "set_mock_params",
             ForeignCall::SetMockReturns => "set_mock_returns",
@@ -42,7 +42,7 @@ impl ForeignCall {
 
     pub(crate) fn lookup(op_name: &str) -> Option<ForeignCall> {
         match op_name {
-            "println" => Some(ForeignCall::Println),
+            "print" => Some(ForeignCall::Print),
             "create_mock" => Some(ForeignCall::CreateMock),
             "set_mock_params" => Some(ForeignCall::SetMockParams),
             "set_mock_returns" => Some(ForeignCall::SetMockReturns),
@@ -92,7 +92,7 @@ pub struct DefaultForeignCallExecutor {
     last_mock_id: usize,
     /// The registered mocks
     mocked_responses: Vec<MockedCall>,
-    /// Whether to print [`ForeignCall::Println`] output.
+    /// Whether to print [`ForeignCall::Print`] output.
     show_output: bool,
 }
 
@@ -120,9 +120,14 @@ impl DefaultForeignCallExecutor {
         decode_string_value(&fields)
     }
 
-    fn execute_println(foreign_call_inputs: &[ForeignCallParam]) -> Result<(), ForeignCallError> {
-        let display_values: PrintableValueDisplay = foreign_call_inputs.try_into()?;
-        println!("{display_values}");
+    fn execute_print(foreign_call_inputs: &[ForeignCallParam]) -> Result<(), ForeignCallError> {
+        let skip_newline = foreign_call_inputs[0].unwrap_value().is_zero();
+        let display_values: PrintableValueDisplay = foreign_call_inputs
+            .split_first()
+            .ok_or(ForeignCallError::MissingForeignCallInputs)?
+            .1
+            .try_into()?;
+        print!("{display_values}{}", if skip_newline { "" } else { "\n" });
         Ok(())
     }
 }
@@ -134,9 +139,9 @@ impl ForeignCallExecutor for DefaultForeignCallExecutor {
     ) -> Result<ForeignCallResult, ForeignCallError> {
         let foreign_call_name = foreign_call.function.as_str();
         match ForeignCall::lookup(foreign_call_name) {
-            Some(ForeignCall::Println) => {
+            Some(ForeignCall::Print) => {
                 if self.show_output {
-                    Self::execute_println(&foreign_call.inputs)?;
+                    Self::execute_print(&foreign_call.inputs)?;
                 }
                 Ok(ForeignCallResult { values: vec![] })
             }

tooling/nargo_fmt/tests/expected/print.nr

@@ -1,5 +1,6 @@
 use dep::std;
 
 fn main() {
+    std::print("Hello world");
     std::println("Hello world");
 }

tooling/nargo_fmt/tests/expected/print2.nr

@@ -1,5 +1,6 @@
 use dep::std;
 
-fn main( ) {
+fn main() {
+    std::print("Hello world");
     std::println("Hello world");
 }

tooling/nargo_fmt/tests/input/print.nr

@@ -1,3 +1,6 @@
 use dep::std;
 
-fn main() { std::println("Hello world"); }
+fn main() {
+    std::print("Hello world");
+    std::println("Hello world");
+}

tooling/nargo_fmt/tests/input/print2.nr

@@ -1,5 +1,6 @@
 use dep::std;
 
-fn main( ) { 
-std::println("Hello world");
+fn main() {
+    std::print("Hello world");
+    std::println("Hello world");
 }