Cannot cmpile: Dependencies and syntax error

[s5k6]

I've tried to install this package as follows:

/tmp/graph-matching$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.0.1
/tmp/graph-matching$ cabal --version
cabal-install version 1.24.0.0
compiled using version 1.24.0.0 of the Cabal library 

/tmp$ git clone https://github.com/ivant/graph-matching.git
/tmp$ cd graph-matching/
/tmp/graph-matching$ git rev-parse HEAD
939bb68d972bea678d561f1d8e26c07f534f2567

/tmp/graph-matching$ cabal sandbox init
/tmp/graph-matching$ cabal install --only-dependencies
cabal: Could not resolve dependencies:
trying: graph-matching-0.2 (user goal)
trying: base-4.9.0.0/installed-4.9... (dependency of graph-matching-0.2)
next goal: transformers (dependency of graph-matching-0.2)
rejecting: transformers-0.5.2.0/installed-0.5..., transformers-0.5.2.0,
transformers-0.5.1.0, transformers-0.5.0.1, transformers-0.5.0.0,
transformers-0.4.3.0, transformers-0.4.2.0, transformers-0.4.1.0,
transformers-0.3.0.0 (conflict: graph-matching => transformers>=0.2.2 && <0.3)
rejecting: transformers-0.2.2.1 (conflict: base==4.9.0.0/installed-4.9...,
transformers => base>=2 && <4.8 || >=1.0 && <2)
rejecting: transformers-0.2.1.0, transformers-0.2.0.0, transformers-0.1.4.0,
transformers-0.1.3.0, transformers-0.1.1.0, transformers-0.1.0.1,
transformers-0.0.1.0, transformers-0.0.0.0, transformers-0.5.0.2,
transformers-0.4.0.0 (conflict: graph-matching => transformers>=0.2.2 && <0.3)
rejecting: transformers-0.2.2.0 (conflict: base==4.9.0.0/installed-4.9...,
transformers => base>=2 && <4.6 || >=1.0 && <2)
rejecting: transformers-0.1.0.0 (conflict: graph-matching =>
transformers>=0.2.2 && <0.3)
Dependency tree exhaustively searched.

I've Tried to remove the upper bounds on all dependencies in
graph-matching.cabal, so that the respective line reads:

Build-depends: base >= 4, containers >= 0.4, array >= 0.3
             , transformers >= 0.2.2

This fails with a syntax error:

/tmp/graph-matching$ cabal build
Package has never been configured. Configuring with default flags. If this
fails, please run configure manually.
Resolving dependencies...
Configuring graph-matching-0.2...
Building graph-matching-0.2...
Preprocessing library graph-matching-0.2...
[1 of 1] Compiling Data.Graph.HopcroftKarp ( Data/Graph/HopcroftKarp.hs, dist/build/Data/Graph/HopcroftKarp.o )

Data/Graph/HopcroftKarp.hs:176:39: error: parse error on input ‘]’

I'm bailing out, sorry