[Python-Dev] Re: Automatic flex interface for Python?
Wed, 21 Aug 2002 21:13:02 -0400
[Eric S. Raymond]
> Lexers are painful in Python.
This is so.
> They hit the language in a weak spot created by the immutability of
But you lost me here -- I don't see a connection between immutability and
either ease of writing lexers or speed of lexers. Indeed, lexers are (IME)
more-or-less exactly as painful and slow written in Perl, where strings are
Seems more to me that lexing is convenient and fast only when expressed in a
language specifically designed for writing lexers, and backed by a
specialized execution engine that knows a great deal about fast
state-machine implementation. Like, say, Flex. Lexing is also clumsy and
slow in SNOBOL4 and Icon, despite that they excel at higher-level
pattern-matching tasks. IOW, lexing is in a world by itself, almost nothing
is good at it, and the few things that shine at it don't do anything else.
y'rs - tim