Resolving dependencies... Configuring data-default-class-0.1.2.0... Configuring dlist-0.8.0.4... Building data-default-class-0.1.2.0... Building dlist-0.8.0.4... Installed data-default-class-0.1.2.0 Configuring nats-1.1.1... Building nats-1.1.1... Installed dlist-0.8.0.4 Configuring numericpeano-0.2.0.0... Installed nats-1.1.1 Configuring old-locale-1.0.0.7... Building numericpeano-0.2.0.0... Building old-locale-1.0.0.7... Installed old-locale-1.0.0.7 Configuring safe-0.3.16... Installed numericpeano-0.2.0.0 Configuring vector-algorithms-0.7.0.1... Building safe-0.3.16... Building vector-algorithms-0.7.0.1... Installed safe-0.3.16 Configuring data-default-instances-containers-0.0.1... Building data-default-instances-containers-0.0.1... Installed data-default-instances-containers-0.0.1 Configuring data-default-instances-dlist-0.0.1... Building data-default-instances-dlist-0.0.1... Installed data-default-instances-dlist-0.0.1 Configuring data-default-instances-old-locale-0.0.1... Building data-default-instances-old-locale-0.0.1... Installed data-default-instances-old-locale-0.0.1 Configuring data-default-0.7.1.1... Installed vector-algorithms-0.7.0.1 Configuring mono-traversable-1.0.8.1... Building data-default-0.7.1.1... Building mono-traversable-1.0.8.1... Installed data-default-0.7.1.1 Configuring type-iso-0.1.0.0... Building type-iso-0.1.0.0... Installed type-iso-0.1.0.0 Installed mono-traversable-1.0.8.1 Configuring string-isos-0.1.0.0... Building string-isos-0.1.0.0... Failed to install string-isos-0.1.0.0 Build log ( /home/builder/.cabal/logs/ghc-8.2.2/string-isos-0.1.0.0-J1MNvxvKq4S6OOFXjQm9Xk.log ): cabal: Entering directory '/tmp/cabal-tmp-10762/string-isos-0.1.0.0' Configuring string-isos-0.1.0.0... Preprocessing library for string-isos-0.1.0.0.. Building library for string-isos-0.1.0.0.. [1 of 2] Compiling Text.Isomorphic ( src/Text/Isomorphic.hs, dist/build/Text/Isomorphic.o ) [2 of 2] Compiling Text.Foldable ( src/Text/Foldable.hs, dist/build/Text/Foldable.o ) src/Text/Foldable.hs:72:11: error: • The default type signature for Text.Foldable.foldMap: forall m. (MonoFoldable s, Element s ~ Char, Monoid m) => (Char -> m) -> s -> m does not match its corresponding non-default type signature • When checking the class method: Text.Foldable.foldMap :: forall s. FoldableString s => (Char -> s) -> s -> s In the class declaration for ‘FoldableString’ | 72 | default foldMap :: (MonoFoldable s, Element s ~ Char, Monoid m) => (Char -> m) -> s -> m | ^^^^^^^ cabal: Leaving directory '/tmp/cabal-tmp-10762/string-isos-0.1.0.0' cabal: Error: some packages failed to install: string-isos-0.1.0.0-J1MNvxvKq4S6OOFXjQm9Xk failed during the building phase. The exception was: ExitFailure 1