Re: [boost] PP: Beta-reducer for closed lambda-terms (save content as lambda.cpp)

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2003-04-12 04:51:27

Vesa Karvonen wrote:
> # This is an applicative order beta-reducer for closed lambda-terms
> # implemented using the C preprocessor.
> #
> # Usage:
> #
> #   cpp lambda.cpp '-DTERM=<term>' |tail -n1|sed 's# ##g'
> #
> # The syntax of lambda-terms:
> #
> #   <term> : LAMBDA(<symbol-or-_>,<term>)
> #          | (<term>,<term>)
> #          | <symbol>
> #
> #   <symbol> : A | B | C | ... | Z
> #   <symbol-or-_> : <symbol> | _

[snip]

> # For example:
> #
> #   cpp lambda.cpp '-DTERM=(LAMBDA(X,X),LAMBDA(Y,Y))' |tail -n1|sed 's#
##g'
> #
> # Prints:
> #
> #   LAMBDA(Y,Y)

Vesa, this is _something_!

I only wish I knew more about lambda-calculus to understand the details, and
the semantics of the term notation itself. Perhaps if you could elaborate a
little bit more on it, and may be provide a few other usage examples an
average PP-library user can associate herself with more easily, some of us
would be able to provide you with a more than just "WOW" feedback - which
this work more than certainly deserves anyway :).

Aleksey