On 3 aug 2007, at 21.34, Simon Peyton-Jones wrote:
I have not been following the recent work on Cabal, but I tried to build in the gap before this patch was committed. I
Fri Aug 3 18:57:01 GMT Daylight Time 2007 Thomas Schilling
* Fix tab in Cabal.cabal.
I was surprised to find that tabs are disallowed in cabal files. Is that really the intention? It seems like a pitfall for the unwary! At the very least, if they must be disallowed, could the error message be more informative? At the moment we get
Setup.exe: Cabal.cabal:70: Unrecognized field format: 'Distribution.Simple.SetupWrapper,'
It’d be better to get
Setup.exe: Cabal.cabal:70: illegal tab character: replace with spaces The problem is, that with conditional statements in .cabal files we really want to allow indenting the field values, e.g.,
if os(linux) { field: value } else { other-field: value . continuation of field value. } Therefore, we had to change the rule for multiline field values to: "To continue a field value, indent the next line _relative to the field name_." (emphasis added) This, unfortunately, made .cabal files susceptible to tab-length. My initial fix (defining tabs to be 8 spaces wide) was rejected[1], and I implemented this (backwards compatible) fix instead. Most (decent) editors can be configured to always use spaces instead of tabs. /Thomas [1] .. excerpt from IRC logs for #ghc, search for "No tabs in .cabal files" http://hackage.haskell.org/trac/hackage/wiki/CabalConfigurations