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Blech version 0.6.0

We are happy to announce a new release of the Blech compiler and language services for VS Code.

Language features are:

  • The syntax of the statement run has changed. It now allows local variable declarations. A return statement may now have an activity call as an argument:

    • run foo = Act()

      used to be foo = run Act()

    • run var foo = Act()

      Here foo is declared in-place and can be used after the run statement.

    • return run Act()

      Here the value returned by Act is directly returned further up.

  • It is now possible to reorder function parameters when linking to external C functions. This is useful to map Blech’s input and output parameters to the single parameter list of a C function:

      @[CFunction(binding = "myCfunction($2, $1)")]
      extern function doStuff(a: nat8)(b: nat8)
    
  • Some annotations may contain string literals. We now support single and (indented) multi line string literals. This is useful if you want to define the right-hand side of a macro as your C-binding:

      @[CFunction (binding = """
                             do {
                               *$2 = $1;
                               *$2 = *$2 + 1;
                             } while (0)
                             """)]
      extern function doStuff(a: nat8)(b: nat8)
    

    Note that you have to follow the Blech-C-interface when accessing Blech parameters from C. $1 is input parameter a: nat8 which is passed by value because it has a simple type. $2 is output parameter b: nat8 which is passed by reference as a pointer.

On the technical side we have fixed a few bugs and issues and improved code generation. The latter now uses “activity contexts” to store activity local data and program counters instead of passing around individual values. This is a preparation for the upcoming module system.