peforth 1.6

A FORTH programming language lives in python and begins with only two words 'code' and 'end-code'.

A FORTH programming language begins with only two words ‘code’ and ‘end-code’.

Ways to run peforth

1. In the project folder run `python __main__.py` or `python __init__.py` or double click them.

2. From above the project folder run `python peforth`

3. If the peforth package is installed. At any folder, run `python -m peforth`

4. If the peforth package is installed. At any folder, run `python` then `import peforth` then type `peforth.ok()` to run it, type `exit` to come back to python interpreter, and do it again and again. peforth context will be all of the same session for all runs.

Install peforth

Use the pip install

pip install peforth

Hello World!

All peforth words have their help messages.

: hi  ( -- ) // The hello world! command
    ." Hello World!!" cr ;
    /// if help message is not enough then use /// leading lines to add comments.
    /// Both // and /// leading messages go to the last word.

The first stack diagram and the `//` leading comment line become help messages. Let’s execute it and see its help:

OK hi
Hello World!!
OK help hi
( -- ) The hello world! command
    if help message is not enough then use /// leading lines to add comments.
    Both // and /// leading messages go to the last word.

`see` command sees a word’s source code and attributes.

OK see hi
{
    "__class__": "Word",
    "__module__": "peforth.projectk",
    "name": "hi",
    "xt": {
        "__class__": "function",
        "__module__": "peforth.projectk"
    },
    "immediate": false,
    "help": "( -- ) The hello world! command",
    "comment": "\tif help message is not enough then use /// leading lines to add comments.\n\tBoth // and /// leading messages goes to the last word.\n",
    "vid": "forth",
    "wid": 242,
    "type": "colon",
    "private": false,
    "cfa": 717
}
------------ Definition in dictionary ------------
00717: Literal: Hello World!! <class 'str'>
00718: . ( x -- ) Print the TOS __str__  (<class 'peforth.projectk.Word'>)
00719: cr ( -- ) print a carriage return __str__  (<class 'peforth.projectk.Word'>)
00720: RET  (<class 'NoneType'>)
------------ End of the difinition ---------------
OK

code … end-code

peforth, like eforth, attempts to use very basic words to build the entire forth system. Actually, peforth is started with only two words `code` and `end-code`. As a demo to define a code word, let’s press Ctrl-D to make the Windows DOS-Box CLI to accept multiple lines at once, then type in the example, and at the end drop another Ctrl-D to terminate the multiple-line input.

OK ^D
code hello
    print('hello world!\n')
end-code
^D
OK

We have defined our first code word `hello`. Let’s execute it and `see` its details,

OK hello
hello world!

OK see hello
{
    "__class__": "Word",
    "__module__": "peforth.projectk",
    "name": "hello",
    "xt": {
        "__class__": "function",
        "__module__": "peforth.projectk",
        "name": "hello"
    },
    "immediate": false,
    "help": "",
    "comment": "",
    "vid": "forth",
    "wid": 243,
    "type": "code"
}
------------ Source code ------------
def xt(_me=None): ### hello ###
    print('hello world!\n')

-------------------------------------
OK

Where `_me` refers to the forth word object itself if you need to access its own attributes.

inline python code

python code can be put inline mixed with forth code. This example defines a `dos-dir` command to go out to DOS box, run the `dir` DOS command, and come back.

OK : dos-dir <py> import os; os.system('dir') </py> ;

Statements in between `<py> ... </py>` are python code. Let’s execute the new word:

OK dos-dir
 Volume in drive C is Windows
 Volume Serial Number is 2EA4-3202

 Directory of c:\Users\hcche\Documents\GitHub\ML\machine-learning-recipes\src\part_5

2017-09-03  16:09    <DIR>          .
2017-09-03  16:09    <DIR>          ..
2017-06-11  08:53               240 check.py
2017-06-23  17:00    <DIR>          Datasets
2017-06-11  08:53             2,218 Fisher.csv
2017-09-03  17:41             6,912 kNNClassifier.f
2017-09-01  19:45             2,256 kNNClassifier.py
2017-06-11  08:53             2,079 Part5.py
2017-09-03  16:09    <DIR>          __pycache__
               5 File(s)         13,705 bytes
               4 Dir(s)  262,004,789,248 bytes free
OK

Again, use `see` to view its source code:

OK see dos-dir
{
    "__class__": "Word",
    "__module__": "peforth.projectk",
    "name": "dos-dir",
    "xt": {
        "__class__": "function",
        "__module__": "peforth.projectk"
    },
    "immediate": false,
    "help": "",
    "comment": "",
    "vid": "forth",
    "wid": 242,
    "type": "colon",
    "private": false,
    "cfa": 717
}
------------ Definition in dictionary ------------
00717: def compyle_anonymous():
    import os; os.system('dir') (<class 'function'>)
  2           0 LOAD_CONST               1 (0)
              2 LOAD_CONST               0 (None)
              4 IMPORT_NAME              0 (os)
              6 STORE_FAST               0 (os)
              8 LOAD_FAST                0 (os)
             10 LOAD_ATTR                1 (system)
             12 LOAD_CONST               2 ('dir')
             14 CALL_FUNCTION            1
             16 POP_TOP
             18 LOAD_CONST               0 (None)
             20 RETURN_VALUE
00718: RET  (<class 'NoneType'>)
------------ End of the difinition ---------------
OK

Now we have seen `<py> ... </py>` brings in a block of python code that does not return value. While `<py> ... </pyV>` is to envelope a python statement that returns a value back to forth’s top of the data stack. We’ll use it’s short form `py>` that followed with a statement without space to get CPU information from DOS environment variable PROCESSOR_IDENTIFIER:

: CPU ( -- string ) // View CPU info
py> os.getenv('PROCESSOR_IDENTIFIER') . cr ;

Type `CPU` to execute the new word:

OK CPU
Intel64 Family 6 Model 142 Stepping 9, GenuineIntel
OK

So `py>` and `py:` are short forms of `<py>...</pyV>` and `<py>...</py>` respectively if the python statement after them do not contain any space character. Visit this project’s Wiki for more examples.

• H.C. Chen, FigTaiwan

• [e-mail]

• 2017.9.21

Edited by: rst online editor