Compile Time Fun Time

[Paul Backus]

On Monday, 25 February 2019 at 06:51:20 UTC, Yevano wrote:
> I am writing a domain specific language of sorts in D for the 
> lambda calculus. One of my requirements is that I should be 
> able to generate expressions like this:
>
> new Abstraction(v1, M)
>
> like this:
>
> L!(x => M)

A word of caution: this kind of thing looks cute, but 
fundamentally, you are using D's lambda syntax in a way it was 
never intended to be used. The more you try to build on top of 
this, the more you will find yourself fighting the language, and 
the more you will be forced to resort to ugly, brittle 
workarounds to make your DSL function.

A much better approach is to write your DSL inside string 
literals, and parse it into proper data structures using CTFE. 
For example:

     L!"x.M"

...would be equivalent to something like:

     Abstraction(Variable("x"), M)