Re: [Haskell-cafe] [Haskell] ANNOUNCE: Diagrams 1.0

18 Jan 2014


      Am 18.01.2014 13:25, schrieb Henning Thielemann:
...
When compiling I get:
src/Diagrams/TwoD/Layout/Tree.hs:448:26:
     No instance for (Default (ForceLayoutOpts R2))
       arising from a use of `def'
     Possible fix:
       add an instance declaration for (Default (ForceLayoutOpts R2))
     In the `_forceLayoutOpts' field of a record
     In the expression:
       FLTOpts
         {_forceLayoutOpts = def, _edgeLen = sqrt 2, _springK = 0.05,
          _staticK = 0.1}
     In an equation for `def':
         def
           = FLTOpts
               {_forceLayoutOpts = def, _edgeLen = sqrt 2, _springK = 0.05,
                _staticK = 0.1}
I guess this problem is best fixed by staying away from data-default, at 
all. I can't believe it is sensible to assign default values to 
arbitrary types.