Related: https://github.com/inducer/pymbolic/blob/master/pymbolic/compiler.py

>>> from pymbolic import compile, var
>>> compile(var("<dt>"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 117, in __init__
    self._compile()
  File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 141, in _compile
    self.__call__ = eval(func_s, ctx)
  File "<string>", line 1
    lambda <dt>: <dt>
           ^
SyntaxError: invalid syntax

>>> compile(var("lambda"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 117, in __init__
    self._compile()
  File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 141, in _compile
    self.__call__ = eval(func_s, ctx)
  File "<string>", line 1
    lambda lambda: lambda
                ^
SyntaxError: invalid syntax

Neat. I was not aware of this. I don't think that's the first time I've re-invented something that you first wrote. It would be nice to be able to use `pymbolic.compiler` instead of my giant hack, but currently there are two issues: * `compile()` doesn't like variables like `<dt>` ```python >>> from pymbolic import compile, var >>> compile(var("<dt>")) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 117, in __init__ self._compile() File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 141, in _compile self.__call__ = eval(func_s, ctx) File "<string>", line 1 lambda <dt>: <dt> ^ SyntaxError: invalid syntax ``` * `compile()` doesn't like variables that are also keywords ```python >>> compile(var("lambda")) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 117, in __init__ self._compile() File "/usr/local/lib/python2.7/site-packages/pymbolic/compiler.py", line 141, in _compile self.__call__ = eval(func_s, ctx) File "<string>", line 1 lambda lambda: lambda ^ SyntaxError: invalid syntax ```

I'm also not sure how well it deals with numpy arrays. Given that the purpose is to speed things up, we probably don't want to run a subst to get rid of those var names. Maybe an optional variable-renaming dict is what the doctor ordered?