End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

Kernel#proc

proc { |...| block } → a_proc

static VALUE
f_proc(VALUE _)
{
    return proc_new(rb_cProc, FALSE, TRUE);
}

Equivalent to Proc.new.

See also #printf #putc #print #puts also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0