Interactive MacroPy - IPython REPL, generic bootstrapper.

metaprogramming, syntactic-macros, macropy, ipython, python, python3, python36
pip install imacropy==0.1.0



Imacropy is interactive macropy.

We provide some agile-development addons for MacroPy, namely an IPython extension to macro-enable its REPL, and a generic macro-enabling bootstrapper.

IPython extension

The extension allows to use macros in the IPython REPL. (Defining macros in the REPL is currently not supported.)

For example:

In [1]: from simplelet import macros, let

In [2]: let((x, 21))[2*x]
Out[2]: 42

A from-import of macros from a given module clears from the REPL session all current macros loaded from that module, and loads the latest definitions of only the specified macros from disk. This allows interactive testing when editing macros.

The most recent definition of any given macro remains alive until the next macro from-import from the same module, or until the IPython session is terminated.

Macro docstrings and source code can be viewed using ? and ??, as usual.

Loading the extension

To load the extension once, %load_ext imacropy.console.

To autoload it when IPython starts, add the string "imacropy.console" to the list c.InteractiveShellApp.extensions in your To find the config file, ipython profile locate.

When the extension loads, it imports macropy into the REPL session. You can use this to debug whether it is loaded, if necessary.

Currently no startup banner is printed, because extension loading occurs after IPython has already printed its own banner. We cannot manually print a banner, because some tools (notably importmagic.el for Emacs, included in Spacemacs) treat the situation as a fatal error in Python interpreter startup if anything is printed (and ipython3 --no-banner is rather convenient to have as the python-shell, to run IPython in Emacs's inferior-shell mode).


The bootstrapper imports the specified file or module, pretending its __name__ is "__main__". This allows your main program to use macros.

For example,

from simplelet import macros, let

def main():
    x = let((y, 21))[2*y]
    assert x == 42
    print("All OK")

if __name__ == "__main__":

Start it as:


A relative path is ok, as long as it is under the current directory. Relative paths including .. are not supported. We also support the -m module_name variant:

macropy3 -m some_program

A dotted module path under the current directory is ok.

If you need to set other Python command-line options:

python3 <your options here> $(which macropy3) -m some_program

This way the rest of the options go to the Python interpreter itself, and the -m some_program to the macropy3 bootstrapper.


From PyPI

Install as user:

pip install imacropy --user

Install as admin:

sudo pip install imacropy

From GitHub

As user:

git clone
cd imacropy
python install --user

As admin, change the last command to

sudo python install




BSD. Copyright 2019 Juha Jeronen and University of Jyväskylä.