monad parsing article....

[S. Alexander Jacobson]

On Wed, 23 Jan 2002, Keith Wansbrough wrote:
> No, it was because they led to extremely confusing error messages.
> This was a particular concern because list comprehensions tend to be
> used a lot by beginners, in assignments designed to demonstrate the
> power and compactness of the language.  If simple typos lead to error
> messages about functors and monads and other arcane and unknown
> concepts, these beginners are liable to be put off; if instead the
> error messages talk about lists then they will be much more useful.

Was it not possible to specialize the error
message rather than the comprehensions?

Alternatively, if the underlying type
information really isn't available, why not give
errors in terms of lists and have language
sophisticates deal with the error message
wierdness (they have to know that "list" in error
messages really means monad).

Or the implementation could simply have a
beginner/advanced error message setting.

I realize this is all water under the bridge, but
personally, I would trade off more simple code for
less readable error messages.

-Alex-

___________________________________________________________________
S. Alexander Jacobson                   i2x Media
1-212-787-1914 voice                    1-603-288-1280 fax