v0.19.1-alpha

0.19.1-alpha "Sunstone" (2022-07-06)

Features

• Support returning nested struct.

  Example:

  pub struct InnerStruct {
      pub inner_s: String<10>
      pub inner_x: i256
  }
  
  pub struct NestedStruct {
      pub inner: InnerStruct
      pub outer_x: i256
  }
  
  contract Foo {
      pub fn return_nested_struct() -> NestedStruct {
          ...
      }
  }
  

  (#635)

• Made some small changes to how the Context object is used.

  • ctx is not required when casting an address to a contract type. Eg let foo: Foo = Foo(address(0))
  • ctx is required when calling an external contract function that requires ctx

  Example:

  use std::context::Context # see issue #679
  
  contract Foo {
    pub fn emit_stuff(ctx: Context) {
      emit Stuff(ctx)  # will be `ctx.emit(Stuff{})` someday
    }
  }
  contract Bar {
    pub fn call_foo_emit_stuff(ctx: Context) {
      Foo(address(0)).emit_stuff(ctx)
    }
  }
  event Stuff {}
  

  (#703)

• Braces! Fe has abandoned python-style significant whitespace in favor of the
  trusty curly brace.

  In addition, elif is now spelled else if, and the pass
  statement no longer exists.

  Example:

  pub struct SomeError {}
  
  contract Foo {
    x: u8
    y: u16
  
    pub fn f(a: u8) -> u8 {
      if a > 10 {
        let x: u8 = 5
        return a + x
      } else if a == 0 {
        revert SomeError()
      } else {
        return a * 10
      }
    }
  
    pub fn noop() {}
  }
  

  (#707)

• traits and generic function parameter

  Traits can now be defined, e.g:

  trait Computable {
    fn compute(self, val: u256) -> u256;
  }
  

  The mechanism to implement a trait is via an impl block e.g:

  struct Linux {
    pub counter: u256
    pub fn get_counter(self) -> u256 {
      return self.counter
    }
    pub fn something_static() -> u256 {
      return 5
    }
  }
  
  impl Computable for Linux {
    fn compute(self, val: u256) -> u256 {
      return val + Linux::something_static() + self.get_counter()
    }
  }
  

  Traits can only appear as bounds for generic functions e.g.:

  struct Runner {
  
    pub fn run<T: Computable>(self, _ val: T) -> u256 {
      return val.compute(val: 1000)
    }
  }
  

  Only struct functions (not contract functions) can have generic parameters.
  The run method of Runner can be called with any type that implements Computable e.g.

  contract Example {
  
    pub fn generic_compute(self) {
      let runner: Runner = Runner();
      assert runner.run(Mac()) == 1001
      assert runner.run(Linux(counter: 10)) == 1015
    }
  }
  

  (#710)

• Generate artifacts for all contracts of an ingot, not just for contracts that are defined in main.fe (#726)

• Allow using complex type as array element type.

  Example:

  contract Foo {
      pub fn bar() -> i256 {
          let my_array: Array<Pair, 3> = [Pair::new(1, 0), Pair::new(2, 0), Pair::new(3, 0)]
  
          let sum: i256 = 0
          for pair in my_array {
              sum += pair.x
          }
  
          return sum
      }
  }
  
  struct Pair {
      pub x: i256
      pub y: i256
    
      pub fn new(_ x: i256, _ y: i256) -> Pair {
          return Pair(x, y)
      }
  }
  

  (#730)

• The fe CLI now has subcommands:

  fe new myproject - creates a new project structure
  fe check . - analyzes fe source code and prints errors
  fe build . - builds a fe project (#732)

• Support passing nested struct types to public functions.

  Example:

  pub struct InnerStruct {
      pub inner_s: String<10>
      pub inner_x: i256
  }
  
  pub struct NestedStruct {
      pub inner: InnerStruct
      pub outer_x: i256
  }
  
  contract Foo {
      pub fn f(arg: NestedStruct) {
          ...
      }
  }
  

  (#733)

• Added support for repeat expressions ([VALUE; LENGTH]).

  e.g.

  let my_array: Array<bool, 42> = [bool; 42] 
  

  Also added checks to ensure array and struct types are initialized. These checks are currently performed at the declaration site, but will be loosened in the future. (#747)

Bugfixes

• Fix a bug that incorrect instruction is selected when the operands of a comp instruction are a signed type. (#734)

• Fix issue where a negative constant leads to an ICE

  E.g. the following code would previously crash the compiler but shouldn't:

  const INIT_VAL: i8 = -1
  contract Foo {
    pub fn init_bar() {
      let x: i8 = INIT_VAL
    }
  }
  

  (#745)

• Fix a bug that causes ICE when nested if-statement has multiple exit point.

  E.g. the following code would previously crash the compiler but shouldn't:

   pub fn foo(self) {
      if true {
          if self.something { 
              return 
          }
      }
      if true {
          if self.something { 
              return 
          }
      }
  }
  

  (#749)