advanced syntax&semantics extension system for Python
First of All
The awareness of low-level implementation details brings the appreciation of an abstraction and the intuitive explanation for it.
This is a saying from my idol in the field of Programming Language.
I present it here, in case anyone prejudging the reliability of this project.
THIS PROJECT SHOULD WORK PERFECTLY UNDER ANY SUPPPORTED PYTHON VERSION(>=3.5), FOR ALL 3-RD PARTY LIBRARIES SUPPORTED IN ANY RELIABLE CPYTHON DISTRIBUTION.
There is no hack but simple static code analyses and ast transformations, and a hack usually contains
inspect.* that I'll never use in this project.
An advanced syntax extension system implemented in pure python.
pip install -U moshmosh-base --no-compile
--no-compile is required.
Working with IPython
You should copy moshmosh_ipy.py
If this directory does not exist, use command
ipython profile create to instantiate.
Some examples about pattern matching, pipelines and quick lambdas:
Some examples about the scoped operators:
Working with regular Python files
moshmosh in your main module:
mypackage.py, start coding with a pragma comment
# moshmosh?, then you can use moshmosh extension system.
Case Study : Pattern Matching
The matching protocol which stems from Python-ideas mailing list is introduced in, which means you can define your own patterns conveniently. The link is here.
# moshmosh? # +pattern-matching class GreaterThan: def __init__(self, v): self.v = v def __match__(self, cnt: int, to_match): if isinstance(to_match, int) and cnt is 0 and to_match > self.v: return () # matched # 'return None' indicates 'unmatched' with match(114, 514): if (GreaterThan(42)() and a, b): print(b, a) # 514 114
Note that the matching clauses should be exhaustive,
might get raised.
The supported Patterns are listed here, which is of course much more powerful than most programming languages.
- And pattern:
pat1 and pat2 and pat3 ...
- Or pattern:
pat1 or pat2 or pat3...
- Pin pattern:
pin(value), this is quite useful. See Elixir Pin Operator
- Literal pattern:
1, "str", 1+2j, (1, 2)
- As pattern:
when(cond1, cond2, cond3)
- Nested patterns:
(pat1, pat2, pat3), (pat1, *pat2, pat3)
[pat1, pat2, pat3], [pat1, *pat2, pat3]
Cons(pat1, pat2, pat3), note that, the function
Cons.__match__(<n arg>, value_to_match)is exact the protocol.
The pattern matching should be more efficient than those hand-written codes without ugly optimizations.
Besides, Moshmosh's pattern matching is orders of magnitude faster than any other alternatives.
Case Study : Template-Python
This is relatively a simple quasiquote implementation, inspired by MetaOCaml. It does not support manual splices or nested quotations, but the function arguments are automatically spliced.
# moshmosh? # +template-python @quote def f(x): x + 1 x = y + 1 from moshmosh.ast_compat import ast from astpretty import pprint stmts = f(ast.Name("a")) pprint(ast.fix_missing_locations(stmts)) pprint(ast.fix_missing_locations(stmts)) # => Expr( lineno=7, col_offset=4, value=BinOp( lineno=7, col_offset=4, left=Name(lineno=7, col_offset=4, id='a', ctx=Load()), op=Add(), right=Num(lineno=7, col_offset=8, n=1), ), ) Assign( lineno=8, col_offset=4, targets=[Name(lineno=8, col_offset=4, id='a', ctx=Store())], value=BinOp( lineno=8, col_offset=8, left=Name(lineno=8, col_offset=8, id='y', ctx=Load()), op=Add(), right=Num(lineno=8, col_offset=12, n=1), ), )
Case Study: Lazy Import
# moshmosh? # +lazy-import import numpy as np # -lazy-import # in fact numpy is not imported here, # and once you use it, it gets imported. def arr10(): # The first time call # arr10 will enforce the import of numpy. return np.zeros(10)
After the lazy modules are actually imported, there's no overhead to access their members.
However, please only import modules when using
The use case is about the necessary cross-import when you want to organise your codebase in a more fine-grained way.
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