!at the end of a method changes the variable in-place (almost like in Ruby):
:=(also available as
\\=), assigns a value to a variable if the current value of the variable is
\\can be used for checking if a variable is defined or not:
ARGVis an Array that contains the program's command-line arguments, that were not given to Sidef.
ENVis an Hash copy of environment variables and their values when the program was started.
ARGFis a FileHandle object used to read lines from argument-files or from
STDINwhen no argument has been specified.
DATAis a FileHandle object that points to the data stored after the
_) is declared at compile-time in each block-object in the program. You may not see its real name very often, because it has been overtaken by the elegant prefix dot (.) operator: