Fix colors on Windows (#749)

Calling the `hSupportsANSIWithoutEmulation` function on Windows 10+
enables terminal colors where supported.
https://hackage.haskell.org/package/ansi-terminal-0.11/docs/System-Console-ANSI.html#v:hSupportsANSIWithoutEmulation

Also has the added benefit that (on Windows), the ANSI codes aren't
present when output is redirected to a text file.

CHANGELOG.md

@@ -14,6 +14,7 @@ Breaking changes (😱!!!):
 
 Bugfixes:
 - Properly call `psa` to avoid warnings (#730)
+- Color output now works on Windows (#749)
 
 Other improvements:
 - `spago build` now detects and warns about unused dependencies (#730, #598)

spago.cabal

@@ -139,7 +139,8 @@ executable spago
  default-extensions: ApplicativeDo BangPatterns BinaryLiterals ConstraintKinds DataKinds DefaultSignatures DeriveDataTypeable DeriveFoldable DeriveFunctor DeriveGeneric DeriveTraversable DerivingStrategies DoAndIfThenElse DuplicateRecordFields EmptyDataDecls ExistentialQuantification FlexibleContexts FlexibleInstances FunctionalDependencies GADTs GeneralizedNewtypeDeriving InstanceSigs KindSignatures LambdaCase LiberalTypeSynonyms MonadFailDesugaring MultiParamTypeClasses MultiWayIf NamedFieldPuns NoImplicitPrelude NoMonomorphismRestriction OverloadedStrings PartialTypeSignatures PatternGuards PolyKinds QuantifiedConstraints RankNTypes RecordWildCards ScopedTypeVariables StandaloneDeriving TupleSections TypeApplications TypeFamilies TypeSynonymInstances UndecidableInstances ViewPatterns
  ghc-options: -Wall -Wcompat -Wincomplete-record-updates -Wredundant-constraints -fprint-potential-instances -optP-Wno-nonportable-include-path
  build-depends:
- base >=4.7 && <5
+ ansi-terminal
+ , base >=4.7 && <5
  , spago
  , text <1.3
  , turtle

src/Spago/RunEnv.hs

@@ -3,6 +3,7 @@ module Spago.RunEnv where
 import Spago.Prelude
 import Spago.Env
 
+import System.Console.ANSI (hSupportsANSIWithoutEmulation)
 import qualified System.Environment as Env
 import qualified Distribution.System as OS
 import qualified RIO
@@ -20,14 +21,17 @@ import qualified Spago.Purs as Purs
 -- and runs the app
 withEnv :: GlobalOptions -> RIO Env a -> IO a
 withEnv GlobalOptions{..} app = do
+ let logHandle = stderr
  let verbose = not globalQuiet && (globalVerbose || globalVeryVerbose)
 
  -- https://github.com/purescript/spago/issues/579
  maybeTerm <- Env.lookupEnv "TERM"
  let termDumb = maybeTerm == Just "dumb" || maybeTerm == Just "win"
- let useColor = globalUseColor && not termDumb
+ supportsAnsi <- hSupportsANSIWithoutEmulation logHandle
+ let useColor = case supportsAnsi of
+ Just True -> globalUseColor && not termDumb
+ _ -> False
 
- let logHandle = stderr
  logOptions' <- logOptionsHandle logHandle verbose
  let logOptions
  = setLogUseTime globalVeryVerbose