[Haskell-cafe] hledget: mtv vs transformers

Dmitry Astapov dastapov at gmail.com
Fri Jan 21 11:44:57 CET 2011

On Fri, Jan 21, 2011 at 3:37 AM, Simon Michael <simon at joyful.com> wrote:

> You mean mtl 2.*, right ?
> Yes that is a problem. I'm nervous about requiring mtl 2 because when I
> bumped hledger 0.13's process dependency to 0.14 for similar reasons it made
> all kinds of trouble for folks who just want to install the hledger core in
> standard/older haskell environments.

Well, chalk me up as the person with standard/old haskell environment :)
I have many versions of GHC installed, plus I have a Haskell Platform from
.debs as provided by Debian/unstable. That version of HP still carries GHC
6.12.1 and mtl 1.*

Using that, it is impossible to "make install" hledger for the reasons
outlined below - you either have to exclude hledger-chart, or build fails.

> On Jan 20, 2011, at 5:11 PM, Dmitry Astapov wrote:
>> Since hledger-chart depends on Chart, which in turn depends on
>> transformers 0.2.*, it will make a sense to bump all mtl dependencies in
>> hledger to 2.2
>> When one does "make install" with older GHC (like 6.12.1, for example),
>> and mtl 1.x is available, it would be happily used for hledger-lib and
>> hledger, but compilation of hledger-chart will pull in transformers 0.2 (but
>> not the newer mtl) and will fail due to conflicting instances.

Dmitry Astapov
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