Calling errors.New in an error path causes a heap allocation at an
already unfortunate moment. It is more efficient to create these error
values in globals and return these constant globals. If these errors are
not used (because the related code was optimized out), the globals will
also be optimized out.
Instead of trying to modify periperhals directly, external functions are
called. For example, __tinygo_gpio_set sets a GPIO pin to a specified
value (high or low). It is expected that binaries made this way will be
linked with some extra libraries that implement support for these
functions.
One particularly interesting case is this experimental board simulator:
https://github.com/aykevl/tinygo-play
Compiling code to WebAssembly with the correct build tag for a board
will enable this board to be simulated in the browser.
Atmel/Microchip based SAMD boards are not currently supported, because
their I2C/SPI support is somewhat uncommon and harder to support in the
machine API. They may require a modification to the machine API for
proper support.
