Clean up after bumping lower bound to GHC 9.6

.github/workflows/ci.yml

@@ -17,10 +17,6 @@ jobs:
         cabal:
           - "latest"
         ghc:
-          - "8.10.7"
-          - "9.0.2"
-          - "9.2.8"
-          - "9.4.8"
           - "9.6.6"
           - "9.8.2"
           - "9.10.3"
@@ -64,13 +60,10 @@ jobs:
         # ghc must match each snapshot's compiler exactly, since we build
         # with --system-ghc against the GHC provisioned by the setup action.
         plan:
-          - { resolver: "--stack-yaml ./stack-8.10.yaml", ghc: "8.10.7" }
-          - { resolver: "--stack-yaml ./stack-9.0.yaml",  ghc: "9.0.2" }
-          - { resolver: "--stack-yaml ./stack-9.2.yaml",  ghc: "9.2.8" }
-          - { resolver: "--stack-yaml ./stack-9.4.yaml",  ghc: "9.4.8" }
           - { resolver: "--stack-yaml ./stack-9.6.yaml",  ghc: "9.6.6" }
           - { resolver: "--stack-yaml ./stack-9.8.yaml",  ghc: "9.8.4" }
           - { resolver: "--stack-yaml ./stack-9.10.yaml", ghc: "9.10.3" }
+          - { resolver: "--stack-yaml ./stack-9.12.yaml", ghc: "9.12.4" }
 
     steps:
     - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0

CHANGELOG.md

@@ -1,4 +1,9 @@
 
+## Unreleased
+
+*   Raise the minimum supported GHC to 9.6 (`base >= 4.18`). Older compilers
+    are no longer tested in CI.
+
 ## 2.4.0
 
 *   Add a `reset` function to the

prometheus.cabal

@@ -10,6 +10,7 @@ maintainer:          luke@bitnomial.com, opensource@bitnomial.com
 copyright:           Bitnomial, Inc. (c) 2016-2023
 category:            Metrics, Monitoring, Web, System
 build-type:          Simple
+tested-with:         GHC == 9.6.6, GHC == 9.8.2, GHC == 9.8.4, GHC == 9.10.3, GHC == 9.12.4
 cabal-version:       >=1.10
 
 description:
@@ -88,7 +89,7 @@ library
                  , System.Metrics.Prometheus.Registry
                  , System.Metrics.Prometheus.RegistryT
 
-  build-depends: base            >= 4.9  && < 5
+  build-depends: base            >= 4.18 && < 5
                , atomic-primops  >= 0.8  && < 0.9
                , bytestring      >= 0.10 && < 0.13
                , containers      >= 0.5  && < 0.8

src/System/Metrics/Prometheus/Concurrent/Registry.hs

@@ -9,7 +9,6 @@ module System.Metrics.Prometheus.Concurrent.Registry (
     sample,
 ) where
 
-import Control.Applicative ((<$>))
 import Control.Concurrent.MVar (
     MVar,
     modifyMVarMasked,

src/System/Metrics/Prometheus/Concurrent/RegistryT.hs

@@ -2,7 +2,6 @@
 
 module System.Metrics.Prometheus.Concurrent.RegistryT where
 
-import Control.Applicative ((<$>))
 import Control.Monad.IO.Class (MonadIO, liftIO)
 import Control.Monad.Trans.Class (MonadTrans)
 import Control.Monad.Trans.Reader (
@@ -23,7 +22,7 @@
  )
 import System.Metrics.Prometheus.Registry (
     RegistrySample,
     listMetricIds,
  )
 
 

src/System/Metrics/Prometheus/Encode/Text.hs

@@ -9,7 +9,6 @@
     intersperse,
  )
 import qualified Data.Map as Map
-import Data.Monoid ((<>))
 
 import System.Metrics.Prometheus.Encode.Text.Histogram (encodeHistogram)
 import System.Metrics.Prometheus.Encode.Text.MetricId (
@@ -45,7 +44,7 @@
     encodeHeader mid sample <> newline
         <> mconcat (intersperse newline $ map encodeMetric group)
   where
     (mid, sample) = head group
 
 
 encodeMetric :: (MetricId, MetricSample) -> Builder

src/System/Metrics/Prometheus/Encode/Text/Histogram.hs

@@ -7,7 +7,6 @@ module System.Metrics.Prometheus.Encode.Text.Histogram (
 import Data.ByteString.Builder (Builder)
 import Data.List (intersperse)
 import qualified Data.Map as Map
-import Data.Monoid ((<>))
 
 import System.Metrics.Prometheus.Encode.Text.MetricId (
     encodeDouble,

src/System/Metrics/Prometheus/Encode/Text/MetricId.hs

@@ -20,7 +20,6 @@ import Data.ByteString.Builder (
     intDec,
  )
 import Data.List (intersperse)
-import Data.Monoid ((<>))
 import Data.Text (Text, replace)
 import Data.Text.Encoding (encodeUtf8)
 import Data.Text.Lazy (toStrict)

src/System/Metrics/Prometheus/Http/Scrape.hs

@@ -7,7 +7,6 @@ module System.Metrics.Prometheus.Http.Scrape (
     prometheusApp,
 ) where
 
-import Control.Applicative ((<$>))
 import Control.Monad.IO.Class (
     MonadIO,
     liftIO,

src/System/Metrics/Prometheus/Metric/Counter.hs

@@ -9,8 +9,7 @@
     set,
 ) where
 
-import Control.Applicative ((<$>))
 import Control.Monad (when)
 import Data.Atomics.Counter (AtomicCounter, incrCounter, newCounter, writeCounter)
 
 

src/System/Metrics/Prometheus/Metric/Gauge.hs

@@ -11,7 +11,6 @@ module System.Metrics.Prometheus.Metric.Gauge (
     modifyAndSample,
 ) where
 
-import Control.Applicative ((<$>))
 import Data.IORef (IORef, atomicModifyIORef', newIORef)
 
 

src/System/Metrics/Prometheus/Metric/Histogram.hs

@@ -12,7 +12,6 @@ module System.Metrics.Prometheus.Metric.Histogram (
     reset,
 ) where
 
-import Control.Applicative ((<$>))
 import Control.Monad (void)
 import Data.Bool (bool)
 import Data.IORef (

src/System/Metrics/Prometheus/MetricId.hs

@@ -7,8 +7,6 @@ import Data.Bifunctor (first)
 import Data.Char (isDigit)
 import Data.Map (Map)
 import qualified Data.Map as Map
-import Data.Monoid (Monoid)
-import Data.Semigroup (Semigroup)
 import Data.String (IsString (..))
 import Data.Text (Text)
 import qualified Data.Text as Text

src/System/Metrics/Prometheus/Registry.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE DeriveDataTypeable #-}
-
 module System.Metrics.Prometheus.Registry (
     Registry,
     RegistrySample (..),
@@ -12,11 +10,9 @@ module System.Metrics.Prometheus.Registry (
     sample,
 ) where
 
-import Control.Applicative ((<$>))
 import Control.Exception (Exception, throw)
 import Data.Map (Map)
 import qualified Data.Map as Map
-import Data.Typeable (Typeable)
 
 import System.Metrics.Prometheus.Metric (
     Metric (..),
@@ -42,7 +38,7 @@ newtype Registry = Registry {unRegistry :: Map MetricId Metric}
 newtype RegistrySample = RegistrySample {unRegistrySample :: Map MetricId MetricSample}
 
 
-newtype KeyError = KeyError MetricId deriving (Show, Typeable)
+newtype KeyError = KeyError MetricId deriving (Show)
 instance Exception KeyError
 
 

src/System/Metrics/Prometheus/RegistryT.hs

@@ -2,7 +2,6 @@
 
 module System.Metrics.Prometheus.RegistryT where
 
-import Control.Applicative ((<$>))
 import Control.Monad.IO.Class (MonadIO, liftIO)
 import Control.Monad.Trans.Class (MonadTrans)
 import Control.Monad.Trans.State.Strict (

stack-9.2.yaml → stack-9.12.yaml

@@ -1,5 +1,5 @@
 ---
-resolver: lts-20.26
+resolver: nightly-2026-10-09
 flags: {}
 packages:
   - "."