Bug#1015776: haskell-lambdabot-core FTBFS: error: Could not deduce

[Adrian Bunk]

Source: haskell-lambdabot-core
Version: 5.3.0.1-1
Severity: serious
Tags: ftbfs bookworm sid

https://buildd.debian.org/status/package.php?p=haskell-lambdabot-core&suite=sid

...
src/Lambdabot/Util.hs:66:15: error:
    • Could not deduce (StatefulGen g0 IO)
        arising from a use of ‘sample’
      from the context: MonadIO m
        bound by the type signature for:
                   random :: forall (m :: * -> *) a. MonadIO m => [a] -> m a
        at src/Lambdabot/Util.hs:65:1-33
      The type variable ‘g0’ is ambiguous
      These potential instances exist:
        three instances involving out-of-scope types
        (use -fprint-potential-instances to see them all)
    • In the first argument of ‘(.)’, namely ‘sample’
      In the second argument of ‘(.)’, namely ‘sample . randomElement’
      In the expression: io . sample . randomElement
   |
66 | random = io . sample . randomElement
   |               ^^^^^^
 at /usr/share/perl5/Debian/Debhelper/Buildsystem/Haskell/Recipes.pm line 107.
	Debian::Debhelper::Buildsystem::Haskell::Recipes::run_quiet("debian/hlibrary.setup", "build", "--builddir=dist-ghc") called at /usr/share/perl5/Debian/Debhelper/Buildsystem/Haskell/Recipes.pm line 131
	Debian::Debhelper::Buildsystem::Haskell::Recipes::run("debian/hlibrary.setup", "build", "--builddir=dist-ghc") called at /usr/share/perl5/Debian/Debhelper/Buildsystem/Haskell/Recipes.pm line 642
	Debian::Debhelper::Buildsystem::Haskell::Recipes::build_recipe() called at -e line 1
make: *** [/usr/share/cdbs/1/class/hlibrary.mk:160: build-ghc-stamp] Error 25