### Usage of `sort_by`

The `sort_by` command also takes a [function argument](#available-function-arguments).
It calls the function on each *line of input*, and uses the results to sort
the *original input* in __ascending__ order.  The `--descending` / `-d` option
will sort the results in __descending__ order.  (There is a `--ascending` / `-a`
option for completeness.)

diff --git a/ft/ft/commands/sort_by.py b/ft/ft/commands/sort_by.py
index b0d0e99..d5e63c0 100644
--- a/ft/ft/commands/sort_by.py
+++ b/ft/ft/commands/sort_by.py
@@ -6,6 +6,19 @@ class SortBy(Command):
     def __init__(self):
         super().__init__("sort_by")
         self.arr = []
+        self.reverse = False
+
+    def add_command_arguments(self, parser):
+        parser.add_argument("--ascending", "-a", dest="reverse",
+                action="store_false", default=False, 
+                help="sort in ascending order (default)")
+        parser.add_argument("--descending", "-d", dest="reverse",
+                action="store_true",
+                help="sort in descending order")
+        return parser
+
+    def parse_additional_command_arguments(self, args):
+        self.reverse = args.reverse
 
     def handle_input(self, value):
         if value.fttype == T_ARRAY and self.column is not None:
@@ -16,5 +29,5 @@ class SortBy(Command):
         self.arr.append((value, result))
 
     def finalize(self):
-        arr = sorted(self.arr, key=lambda x: x[1])
+        arr = sorted(self.arr, key=lambda x: x[1], reverse=self.reverse)
         list(map(lambda x: self.print_formatted(x[0]), arr))

__________________________________________________________________________________________ test_add_dynamic_type ___________________________________________________________________________________________

    def test_add_dynamic_type():
        assert add_dynamic_type("True").fttype == T_BOOL
>       assert add_dynamic_type("-1223").fttype == T_INT
E       AssertionError: assert String == Int
E        +  where String = TypedValue('-1223', String).fttype
E        +    where TypedValue('-1223', String) = add_dynamic_type('-1223')

ft/test_command.py:7: AssertionError

seq 5 | filter is_odd

1
3
5

@functools.func("Int", "Bool") #or @functools.func(int, bool)
def is_odd(a: int) -> bool:
    return a % 2 == 1

@register("join")
@typed(None, T_STRING)
def join(separator, inp):
    if type(inp) == list:
        separator = dynamic_cast(T_STRING, separator).value
        vals = map(lambda x: T_STRING.create_from(x).value, inp)
        return separator.join(vals)

    return inp   # Only one 'column'

$ touch /tmp/ft-source
$ ln -s /tmp/ft-source /tmp/ft-destination
$ ls /tmp/ft-* | map is_link
False
False

> echo -e '1\t2' | filter -c1 odd
Traceback (most recent call last):
  File "/home/jdhedden/bin/filter", line 6, in <module>
    Filter().run()
  File "/mnt/data/Computer/Linux/shell-functools/ft/ft/command.py", line 101, in run
    self.handle_input(value)
  File "/mnt/data/Computer/Linux/shell-functools/ft/ft/commands/filter.py", line 34, in handle_input
    self.print_formatted(value)
  File "/mnt/data/Computer/Linux/shell-functools/ft/ft/command.py", line 78, in print_formatted
    formatted = ftformat(result)
  File "/mnt/data/Computer/Linux/shell-functools/ft/ft/internal.py", line 17, in ftformat
    return "\t".join(map(ftformat, val.value))
TypeError: sequence item 0: expected str instance, int found

diff --git a/ft/ft/internal.py b/ft/ft/internal.py
index 33ee227..b8a981f 100644
--- a/ft/ft/internal.py
+++ b/ft/ft/internal.py
@@ -13,7 +13,7 @@ def colored(inp, col):
 
 def ftformat(val):
     if val.fttype == T_ARRAY:
-        return "\t".join(map(ftformat, val.value))
+        return "\t".join(map(str, map(ftformat, val.value)))
     elif val.fttype == T_PATH:
         return colored(val.value, "cyan")
     elif val.fttype == T_STRING:

> echo -e '1\t2' | filter -c1 odd
1	2

ls | filter is_file

[functools error] Incompatible input type: expected 'Path', got 'Int'

> seq 3 | map %append "-"
-1
-2
-3

> seq 3 | filter %contains "12"
1
2

@register("run")
@typed(T_ARRAY, T_VOID)
def run(command, inp):
    command = dynamic_cast(T_STRING, command).value.split()
    args = map(T_STRING.create_from, inp)
    args = list(map(lambda v: v.value, args))

    print("Running '{}' with arguments {}".format(command, args))
    subprocess.call(command + args)

### Usage of `run`

The `run` *function* executes a command over arguments presented:

seq 10 | take_while lt 4
ls | take_while starts_with a

@register("format")
@typed(None, T_STRING)
def format(format_str, inp):
    try:
        if type(inp) == list:
            args = list(map(lambda v: v.value, inp))
            return format_str.value.format(*args)
        else:
            return format_str.value.format(inp)
    except ValueError:
        panic("Incorrect format string '{}' for input '{}'.".format(format_str.value, inp))
    except IndexError:
        if type(inp) == list:
            count = len(inp)
        else:
            count = 1
        panic("Not enough arguments (only {} given) for format string '{}'.".format(count, format_str.value))

> echo -e '1\tone' | map format "'{}' is spelled '{}'"
'1' is spelled 'one'

ls | map <TAB>

$ pip3 install shell-functions 
Collecting shell-functions
Could not install packages due to an EnvironmentError: 404 Client Error: Not Found for url: https://pypi.org/simple/shell-functions/