2023-09-15: Fuzion September Update

Here is this month's update:

Even though August was a holiday month for the entire Fuzion team, many exciting things have happened.

The largest change was the addition of a first experimental version of the JVM bytecode backend (#1854), which brings an enormous performance boost compared to the interpreter.

A summary of the most important changes:

• Fuzion language

  • flag error when assigning choice element to this type of type feature: #1793.

• front end

  • handle boxing of erroneous and empty values gracefully, fixes a user-visible exception when compiling errorneous code: #1795.

  • parser: allow closing brace of formal args list at min indent, #1803.

  • an error is produced if a field is added to a primitive type like i32, this used to cause a crash in the backend: #1808.

  • improved backward type propagation for arrays, #1814.

    This means that

    
        a array i32 := []
              

    works as expected, whereas previously the right side would have type array void resulting an in incompatible type error.

  • fixed a regression which broke the lookup of nontype features that match a type name which led to poor error messages: #1826.

  • introduced an explicit error message when using a choice type as a constraint for a type parameter: #1836.

  • Allow result type in declaration using => #1890.

    This means that

    
        foo i32 => 42
              

    is now a valid feature declaration, and this syntax will eventually replace the is syntax for feature declarations.

• fz command

  • for -effects option, added check if used effect is instantiated: #1916.

• JVM back end

• added first, incomplete version of a JVM bytecode backend (#1848, #1854) and first bug fixes (#1883, #1885, #1887, #1891, #1892, #1896, #1897, #1901, #1905, #1909, #1910, #1923, #1924, #1927).

  There are two new options to the fz command:

  • -jvm creates class files and immediately loads them via a ClassLoader and executes the code, similar to -interpreter, and
  • -classes that creates a directory fuzion_generated_classes that contains class files.

  Biggest restrictions right now

  • Only part of the intrinsics are implemented
  • value types are not copied when assigned such that they have reference semantics.
  • no threads
  • no abort for effects
  • many other minor things, many marked with NYI in the sources

interpreter

• fix tanh intrinsic: #1868.

base library

• The atan2 feature for floating point numbers is now implemented in pure Fuzion. This was necessary due to differences in the implementation of atan2 in the C standard libraries on various platforms. #1791.

• Moved ps_sets features to ps_set.type, #1738.

• revamped intrinsics related to file I/O, in particular to reading and writing from standard in, out, and error: #1789.

• renamed quantors as quantor: #1810.

• adjustments to the visibility of various features: #1786, #1745, #1823, #1824, #1841, #1851, #1911.

Cheers,

--The Fuzion Team.