"ghc --make hakyll.hs" error

[luckypoem]

hi.

root@AR:/usr/local/brianshourd.com# ghc --make hakyll.hs
[1 of 1] Compiling Main ( hakyll.hs, hakyll.o )

hakyll.hs:173:42: error:
• Couldn't match type ‘unordered-containers-0.2.7.1:Data.HashMap.Base.HashMap
Data.Text.Internal.Text
aeson-0.11.2.1:Data.Aeson.Types.Internal.Value’
with ‘containers-0.5.7.1:Data.Map.Base.Map [Char] [Char]’
Expected type: containers-0.5.7.1:Data.Map.Base.Map [Char] [Char]
Actual type: Metadata
• In the second argument of ‘Data.Map.lookup’, namely ‘metadata’
In the expression: Data.Map.lookup "math" metadata
In the second argument of ‘($)’, namely
‘case Data.Map.lookup "math" metadata of {
Just "true"
-> "<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML\" />"
otherwise -> "" }’
root@AR:/usr/local/brianshourd.com#

how to fix it?