Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: scyther-proof (user goal)
rejecting: scyther-proof-0.10.0.1, scyther-proof-0.10.0.0,
scyther-proof-0.8.0.0, scyther-proof-0.6.0.0, scyther-proof-0.5.0.0,
scyther-proof-0.4.1.0 (constraint from user target requires ==0.4.0)
trying: scyther-proof-0.4.0
trying: base-4.9.0.0/installed-4.9... (dependency of scyther-proof-0.4.0)
next goal: json (dependency of scyther-proof-0.4.0)
rejecting: json-0.9.1, json-0.9, json-0.8, json-0.7, json-0.6 (conflict:
scyther-proof => json==0.5.*)
rejecting: json-0.5 (conflict: base==4.9.0.0/installed-4.9..., json => base>=4
&& <4.8 || >=3 && <4.8 || <3)
rejecting: json-0.4.4, json-0.4.3, json-0.4.2, json-0.4.1, json-0.3.6,
json-0.3.3 (conflict: scyther-proof => json==0.5.*)
Dependency tree exhaustively searched.