The have really simplified things with the
nucleo, it plugs into your usb port and they have a web based development environment, you just give 'em an email address for access. When you compile, it all happens on the server, where they control all the setup and versions of tools and whatnot, and you save the downloaded bin to your usb device, where it automatically loads.
$10 for 40 12 bit adc pins in an even easier (and more predictable) than arduino to set up environment.
Development Platform for Devices | mbed
Don't expect anything like assembler though, You will have to "baremetal" it as the plebes say
i.e.
https://launchpad.net/gcc-arm-embedded <- which is gnu C++ and being supported by ARM developers directly (and isn't scared of some asm). Probably your first option for the discovery boards too, or olimex boards.