GHC(1)

NAME
ghc - the Glasgow Haskell Compiler

SYNOPSIS

ghc [option|filename]
ghci [option|filename]

DESCRIPTION

This manual page documents briefly the ghc and ghci commands. Note that ghci is not yet available on all architectures. Extensive documentation is available in various other formats including PDF and HTML.

Each of GHC's command line options is classified as either static or dynamic. A static flag may only be specified on the command line, whereas a dynamic flag may also be given in an OPTIONS pragma in a source file or set from the GHCi command-line with :set .

As a rule of thumb, all the language options are dynamic, as are the warning options and the debugging options.

The rest are static, with the notable exceptions of -v, -cpp, -fasm, -fvia-C, -fllvm, and -#include. The OPTIONS sections lists the status of each flag.

Common suffixes of file names for Haskell are:

.hs Haskell source code; preprocess, compile

.lhs
    literate Haskell source; unlit, preprocess, compile

.hi Interface file; contains information about exported symbols

.hc intermediate C files

.⟨way⟩_o
    object files for "way" ⟨way⟩; common ways are:

dyn dynamically-linked

p   built with profiling

.⟨way⟩_hi
    interface files for "way" ⟨way⟩; common ways are:

OPTIONS

Code generation
    -dynamic-too -fasm -fllvm -fbyte-code -fexternal-dynamic-refs -fllvm -fasm -fno-code -fobject-code -fPIC -fPIE -fwrite-interface

Debugging the compiler
    -dcmm-lint -dcore-lint -ddump-asm -ddump-asm-expanded -ddump-asm-liveness -ddump-asm-native -ddump-asm-regalloc -ddump-asm-regalloc-stages -ddump-asm-stats -ddump-bcos -ddump-cfg-weights -ddump-cmm -ddump-cmm-caf -ddump-cmm-cbe -ddump-cmm-cfg -ddump-cmm-cps -ddump-cmm-from-stg -ddump-cmm-info -ddump-cmm-proc -ddump-cmm-procmap -ddump-cmm-raw -ddump-cmm-sink -ddump-cmm-sp -ddump-cmm-split -ddump-cmm-switch -ddump-cmm-verbose -ddump-cmm-verbose-by-proc -ddump-core-stats -ddump-cse -ddump-deriv -ddump-ds -ddump-ds-preopt -ddump-ec-trace -ddump-file-prefix=⟨str⟩ -ddump-foreign -ddump-hpc -ddump-if-trace -ddump-inlinings -ddump-json -ddump-llvm -ddump-mod-map -ddump-occur-anal -ddump-opt-cmm -ddump-parsed -ddump-parsed-ast -ddump-prep -ddump-rn -ddump-rn-ast -ddump-rn-stats -ddump-rn-trace -ddump-rtti -ddump-rule-firings -ddump-rule-rewrites -ddump-rules -ddump-simpl -ddump-simpl-iterations -ddump-simpl-stats -ddump-spec -ddump-splices -ddump-stg -ddump-stg-final -ddump-stg-unarised -ddump-str-signatures -ddump-stranal -ddump-tc -ddump-tc-ast -ddump-tc-trace -ddump-ticked -ddump-timings -ddump-to-file -ddump-types -ddump-worker-wrapper -dfaststring-stats -dhex-word-literals -dinitial-unique=⟨s⟩ -dinline-check=⟨str⟩ -dno-debug-output -ddebug-output -dno-typeable-binds -dppr-case-as-let -dppr-cols=⟨n⟩ -dppr-debug -dppr-user-length -drule-check=⟨str⟩ -dshow-passes -dstg-lint -dsuppress-all -dsuppress-coercions -dsuppress-idinfo -dsuppress-module-prefixes -dsuppress-stg-free-vars -dsuppress-ticks -dsuppress-timestamps -dsuppress-type-applications -dsuppress-type-signatures -dsuppress-unfoldings -dsuppress-uniques -dsuppress-var-kinds -dth-dec-file -dunique-increment=⟨i⟩ -dverbose-core2core -dverbose-stg2stg -falignment-sanitisation -fcatch-bottoms -fllvm-fill-undef-with-garbage -fproc-alignment -g -g⟨n⟩

C pre-processor
    -cpp -D⟨symbol⟩[=⟨value⟩] -U⟨symbol⟩ -I⟨dir⟩ -U⟨symbol⟩

Finding imports
    -i -i⟨dir⟩[:⟨dir⟩]*

Interactive mode
    -fbreak-on-error -fno-break-on-error -fbreak-on-exception -fno-break-on-exception -fghci-hist-size=⟨n⟩ -fghci-leak-check -fno-ghci-leak-check -flocal-ghci-history -fno-local-ghci-history -fno-it -fno-no-it -fprint-bind-result -fno-print-bind-result -fprint-evld-with-show -fshow-loaded-modules -ghci-script -ignore-dot-ghci -interactive-print ⟨name⟩

Interface files
    --show-iface ⟨file⟩ -ddump-hi -ddump-hi-diffs -ddump-minimal-imports

Keeping intermediate files
    -keep-hc-file -keep-hc-files -keep-hi-files -no-keep-hi-files -keep-hscpp-file -keep-hscpp-files -keep-llvm-file -keep-llvm-files -keep-o-files -no-keep-o-files -keep-s-file -keep-s-files -keep-tmp-files

Language options
    -fno-safe-haskell -fsort-by-size-hole-fits -fno-sort-by-size-hole-fits -fsort-by-subsumption-hole-fits -fno-sort-by-subsumption-hole-fits -Winferred-safe-imports -Wno-inferred-safe-imports -Wmissing-safe-haskell-mode -Wno-missing-safe-haskell-mode -XAllowAmbiguousTypes -XApplicativeDo -XArrows -XBangPatterns -XBinaryLiterals -XBlockArguments -XCApiFFI -XConstrainedClassMethods -XConstraintKinds -XCPP -XCUSKs -XDataKinds -XDatatypeContexts -XDefaultSignatures -XDeriveAnyClass -XDeriveDataTypeable -XDeriveFoldable -XDeriveFunctor -XDeriveGeneric -XDeriveLift -XDeriveTraversable -XDerivingStrategies -XDerivingVia -XDisambiguateRecordFields -XDuplicateRecordFields -XEmptyCase -XEmptyDataDecls -XEmptyDataDeriving -XExistentialQuantification -XExplicitForAll -XExplicitNamespaces -XExtendedDefaultRules -XFlexibleContexts -XFlexibleInstances -XForeignFunctionInterface -XFunctionalDependencies -XGADTs -XGADTSyntax -XGeneralisedNewtypeDeriving -XGeneralizedNewtypeDeriving -XHaskell2010 -XHaskell98 -XHexFloatLiterals -XImplicitParams -XImportQualifiedPost -XImpredicativeTypes -XIncoherentInstances -XInstanceSigs -XInterruptibleFFI -XKindSignatures -XLambdaCase -XLiberalTypeSynonyms -XMagicHash -XMonadComprehensions -XMonadFailDesugaring -XMonoLocalBinds -XMultiParamTypeClasses -XMultiWayIf -XNamedFieldPuns -XNamedWildCards -XNegativeLiterals -XNoImplicitPrelude -XNoMonomorphismRestriction -XNondecreasingIndentation -XNoPatternGuards -XNoTraditionalRecordSyntax -XNPlusKPatterns -XNullaryTypeClasses -XNumDecimals -XNumericUnderscores -XOverlappingInstances -XOverloadedLabels -XOverloadedLists -XOverloadedStrings -XPackageImports -XParallelListComp -XPartialTypeSignatures -XPatternSynonyms -XPolyKinds -XPostfixOperators -XQuantifiedConstraints -XQuasiQuotes -XRank2Types -XRankNTypes -XRebindableSyntax -XRecordWildCards -XRecursiveDo -XRoleAnnotations -XSafe -XScopedTypeVariables -XStandaloneDeriving -XStandaloneKindSignatures -XStarIsType -XStaticPointers -XStrict -XStrictData -XTemplateHaskell -XTemplateHaskellQuotes -XTransformListComp -XTrustworthy -XTupleSections -XTypeApplications -XTypeFamilies -XTypeFamilyDependencies -XTypeInType -XTypeOperators -XTypeSynonymInstances -XUnboxedSums -XUnboxedTuples -XUndecidableInstances -XUndecidableSuperClasses -XUnicodeSyntax -XUnliftedFFITypes -XUnliftedNewtypes -XUnsafe -XViewPatterns

Linking options
    -c -debug -dylib-install-name ⟨path⟩ -dynamic -dynload -eventlog -fno-embed-manifest -fno-gen-manifest -fno-shared-implib -framework ⟨name⟩ -framework-path ⟨dir⟩ -fwhole-archive-hs-libs -keep-cafs -L ⟨dir⟩ -l ⟨lib⟩ -main-is ⟨thing⟩ -no-hs-main -no-rtsopts-suggestions -package ⟨name⟩ -pie -rdynamic -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩] -shared -split-sections -static -staticlib -threaded -with-rtsopts=⟨opts⟩

Miscellaneous options
    -fexternal-interpreter -fglasgow-exts -fno-glasgow-exts -ghcversion-file ⟨path to ghcversion.h⟩ -H ⟨size⟩ -j[⟨n⟩]

Modes of operation
    --frontend ⟨module⟩ --help -? --info --interactive --make --mk-dll --numeric-version --print-libdir --show-iface ⟨file⟩ --show-options --supported-extensions --supported-languages --version -V -e ⟨expr⟩ -M

Individual optimizations
    -fasm-shortcutting -fno-asm-shortcutting -fbinary-blob-threshold=⟨n⟩ -fblock-layout-cfg -fno-block-layout-cfg -fblock-layout-weightless -fno-block-layout-weightless -fblock-layout-weights -fcall-arity -fno-call-arity -fcase-folding -fno-case-folding -fcase-merge -fno-case-merge -fcmm-elim-common-blocks -fno-cmm-elim-common-blocks -fcmm-sink -fno-cmm-sink -fcpr-anal -fno-cpr-anal -fcross-module-specialise -fno-cross-module-specialise -fcse -fno-cse -fdicts-cheap -fno-dicts-cheap -fdicts-strict -fno-dicts-strict -fdmd-tx-dict-sel -fno-dmd-tx-dict-sel -fdo-eta-reduction -fno-do-eta-reduction -fdo-lambda-eta-expansion -fno-do-lambda-eta-expansion -feager-blackholing -fenable-rewrite-rules -fno-enable-rewrite-rules -fexcess-precision -fno-excess-precision -fexitification -fno-exitification -fexpose-all-unfoldings -fno-expose-all-unfoldings -ffloat-in -fno-float-in -ffull-laziness -fno-full-laziness -ffun-to-thunk -fno-fun-to-thunk -fignore-asserts -fno-ignore-asserts -fignore-interface-pragmas -fno-ignore-interface-pragmas -flate-dmd-anal -fno-late-dmd-anal -flate-specialise -fno-late-specialise -fliberate-case -fno-liberate-case -fliberate-case-threshold=⟨n⟩ -fno-liberate-case-threshold -fllvm-pass-vectors-in-regs -fno-llvm-pass-vectors-in-regs -floopification -fno-loopification -fmax-inline-alloc-size=⟨n⟩ -fmax-inline-memcpy-insns=⟨n⟩ -fmax-inline-memset-insns=⟨n⟩ -fmax-simplifier-iterations=⟨n⟩ -fmax-uncovered-patterns=⟨n⟩ -fmax-worker-args=⟨n⟩ -fno-opt-coercion -fno-pre-inlining -fno-state-hack -fomit-interface-pragmas -fno-omit-interface-pragmas -fomit-yields -fno-omit-yields -foptimal-applicative-do -fno-optimal-applicative-do -fpedantic-bottoms -fno-pedantic-bottoms -fregs-graph -fno-regs-graph -fregs-iterative -fno-regs-iterative -fsimpl-tick-factor=⟨n⟩ -fsimplifier-phases=⟨n⟩ -fsolve-constant-dicts -fno-solve-constant-dicts -fspec-constr -fno-spec-constr -fspec-constr-count=⟨n⟩ -fno-spec-constr-count -fspec-constr-keen -fno-spec-constr-keen -fspec-constr-threshold=⟨n⟩ -fno-spec-constr-threshold -fspecialise -fno-specialise -fspecialise-aggressively -fno-specialise-aggressively -fstatic-argument-transformation -fno-static-argument-transformation -fstg-cse -fno-stg-cse -fstg-lift-lams -fno-stg-lift-lams -fstg-lift-lams-known -fno-stg-lift-lams-known -fstg-lift-lams-non-rec-args -fno-stg-lift-lams-non-rec-args-any -fstg-lift-lams-rec-args -fno-stg-lift-lams-rec-args-any -fstrictness -fno-strictness -fstrictness-before=⟨n⟩ -funbox-small-strict-fields -fno-unbox-small-strict-fields -funbox-strict-fields -fno-unbox-strict-fields -funfolding-creation-threshold=⟨n⟩ -funfolding-dict-discount=⟨n⟩ -funfolding-fun-discount=⟨n⟩ -funfolding-keeness-factor=⟨n⟩ -funfolding-use-threshold=⟨n⟩ -fworker-wrapper

Optimization levels
    -O -O1 -O0 -O0 -O2 -O0 -O⟨n⟩ -O0

Package options
    -clear-package-db -distrust ⟨pkg⟩ -distrust-all-packages -fpackage-trust -global-package-db -hide-all-packages -hide-package ⟨pkg⟩ -ignore-package ⟨pkg⟩ -no-auto-link-packages -no-global-package-db -no-user-package-db -package ⟨pkg⟩ -package-db ⟨file⟩ -package-env ⟨file⟩|⟨name⟩ -package-id ⟨unit-id⟩ -this-unit-id ⟨unit-id⟩ -trust ⟨pkg⟩ -user-package-db

Phases of compilation
    -C -c -E -F -S -x ⟨suffix⟩

Overriding external programs
    -pgma ⟨cmd⟩ -pgmc ⟨cmd⟩ -pgmdll ⟨cmd⟩ -pgmF ⟨cmd⟩ -pgmi ⟨cmd⟩ -pgmL ⟨cmd⟩ -pgml ⟨cmd⟩ -pgmlc ⟨cmd⟩ -pgmlibtool ⟨cmd⟩ -pgmlo ⟨cmd⟩ -pgmP ⟨cmd⟩ -pgms ⟨cmd⟩ -pgmwindres ⟨cmd⟩

Phase-specific options
    -opta ⟨option⟩ -optc ⟨option⟩ -optcxx ⟨option⟩ -optdll ⟨option⟩ -optF ⟨option⟩ -opti ⟨option⟩ -optL ⟨option⟩ -optl ⟨option⟩ -optlc ⟨option⟩ -optlo ⟨option⟩ -optP ⟨option⟩ -optwindres ⟨option⟩

Platform-specific options
    -mbmi2 -msse2 -msse4.2

Compiler plugins
    -fclear-plugins -fplugin-opt=⟨module⟩:⟨args⟩ -fplugin-trustworthy -fplugin=⟨module⟩ -hide-all-plugin-packages -plugin-package ⟨pkg⟩ -plugin-package-id ⟨pkg-id⟩

Profiling
    -fno-prof-auto -fprof-auto -fno-prof-cafs -fprof-cafs -fno-prof-count-entries -fprof-count-entries -fprof-auto -fno-prof-auto -fprof-auto-calls -fno-prof-auto-calls -fprof-auto-exported -fno-prof-auto -fprof-auto-top -fno-prof-auto -fprof-cafs -fno-prof-cafs -prof -ticky

Program coverage
    -fhpc

Recompilation checking
    -fforce-recomp -fno-force-recomp -fignore-hpc-changes -fno-ignore-hpc-changes -fignore-optim-changes -fno-ignore-optim-changes

Redirecting output
    --exclude-module=⟨file⟩ -ddump-mod-cycles -dep-makefile ⟨file⟩ -dep-suffix ⟨suffix⟩ -dumpdir ⟨dir⟩ -hcsuf ⟨suffix⟩ -hidir ⟨dir⟩ -hiedir ⟨dir⟩ -hiesuf ⟨suffix⟩ -hisuf ⟨suffix⟩ -include-cpp-deps -include-pkg-deps -o ⟨file⟩ -odir ⟨dir⟩ -ohi ⟨file⟩ -osuf ⟨suffix⟩ -outputdir ⟨dir⟩ -stubdir ⟨dir⟩

Temporary files
    -tmpdir ⟨dir⟩

Verbosity options
    -fabstract-refinement-hole-fits -fno-abstract-refinement-hole-fits -fdefer-diagnostics -fdiagnostics-color=⟨always|auto|never⟩ -fdiagnostics-show-caret -fno-diagnostics-show-caret -ferror-spans -fhide-source-paths -fkeep-going -fmax-refinement-hole-fits=⟨n⟩ -fno-max-refinement-hole-fits -fmax-relevant-binds=⟨n⟩ -fno-max-relevant-binds -fmax-valid-hole-fits=⟨n⟩ -fno-max-valid-hole-fits -fno-show-valid-hole-fits -fno-sort-valid-hole-fits -fsort-valid-hole-fits -fprint-axiom-incomps -fno-print-axiom-incomps -fprint-equality-relations -fno-print-equality-relations -fprint-expanded-synonyms -fno-print-expanded-synonyms -fprint-explicit-coercions -fno-print-explicit-coercions -fprint-explicit-foralls -fno-print-explicit-foralls -fprint-explicit-kinds -fno-print-explicit-kinds -fprint-explicit-runtime-reps -fno-print-explicit-runtime-reps -fprint-potential-instances -fno-print-potential-instances -fprint-typechecker-elaboration -fno-print-typechecker-elaboration -fprint-unicode-syntax -fno-print-unicode-syntax -frefinement-level-hole-fits=⟨n⟩ -fno-refinement-level-hole-fits -freverse-errors -fno-reverse-errors -fshow-docs-of-hole-fits -fno-show-docs-of-hole-fits -fshow-hole-constraints -fshow-hole-matches-of-hole-fits -fno-show-hole-matches-of-hole-fits -fshow-provenance-of-hole-fits -fno-show-provenance-of-hole-fits -fshow-type-app-of-hole-fits -fno-show-type-app-of-hole-fits -fshow-type-app-vars-of-hole-fits -fno-show-type-app-vars-of-hole-fits -fshow-type-of-hole-fits -fno-type-of-hole-fits -funclutter-valid-hole-fits -Rghc-timing -v -v⟨n⟩

Warnings
    -fdefer-out-of-scope-variables -fno-defer-out-of-scope-variables -fdefer-type-errors -fno-defer-type-errors -fdefer-typed-holes -fno-defer-typed-holes -fenable-th-splice-warnings -fno-enable-th-splices -fhelpful-errors -fno-helpful-errors -fmax-pmcheck-models=⟨n⟩ -fshow-warning-groups -fno-show-warning-groups -fvia-C -W -w -w -Wall -w -Wall-missed-specialisations -Wno-all-missed-specialisations -Wcompat -Wno-compat -Wcompat-unqualified-imports -Wno-compat-unqualified-imports -Wcpp-undef -Wdeferred-out-of-scope-variables -Wno-deferred-out-of-scope-variables -Wdeferred-type-errors -Wno-deferred-type-errors -Wdeprecated-flags -Wno-deprecated-flags -Wdeprecations -Wno-deprecations -Wderiving-defaults -Wno-deriving-defaults -Wdodgy-exports -Wno-dodgy-exports -Wdodgy-foreign-imports -Wno-dodgy-foreign-import -Wdodgy-imports -Wno-dodgy-imports -Wduplicate-constraints -Wno-duplicate-constraints -Wduplicate-exports -Wno-duplicate-exports -Wempty-enumerations -Wno-empty-enumerations -Werror -Wwarn -Weverything -Whi-shadowing -Wno-hi-shadowing -Widentities -Wno-identities -Wimplicit-kind-vars -Wno-implicit-kind-vars -Wimplicit-prelude -Wno-implicit-prelude -Winaccessible-code -Wno-inaccessible-code -Wincomplete-patterns -Wno-incomplete-patterns -Wincomplete-record-updates -Wno-incomplete-record-updates -Wincomplete-uni-patterns -Wno-incomplete-uni-patterns -Winline-rule-shadowing -Wno-inline-rule-shadowing -Wmissed-extra-shared-lib -Wno-missed-extra-shared-lib -Wmissed-specialisations -Wno-missed-specialisations -Wmissing-deriving-strategies -Wno-missing-deriving-strategies -Wmissing-export-lists -fnowarn-missing-export-lists -Wmissing-exported-signatures -Wno-missing-exported-signatures -Wmissing-exported-sigs -Wno-missing-exported-sigs -Wmissing-fields -Wno-missing-fields -Wmissing-home-modules -Wno-missing-home-modules -Wmissing-import-lists -fnowarn-missing-import-lists -Wmissing-local-signatures -Wno-missing-local-signatures -Wmissing-local-sigs -Wno-missing-local-sigs -Wmissing-methods -Wno-missing-methods -Wmissing-monadfail-instances -Wno-missing-monadfail-instances -Wmissing-pattern-synonym-signatures -Wno-missing-pattern-synonym-signatures -Wmissing-signatures -Wno-missing-signatures -Wmonomorphism-restriction -Wno-monomorphism-restriction -Wname-shadowing -Wno-name-shadowing -Wno-compat -Wcompat -Wnoncanonical-monad-instances -Wno-noncanonical-monad-instances -Wnoncanonical-monadfail-instances -Wno-noncanonical-monadfail-instances -Wnoncanonical-monoid-instances -Wno-noncanonical-monoid-instances -Worphans -Wno-orphans -Woverflowed-literals -Wno-overflowed-literals -Woverlapping-patterns -Wno-overlapping-patterns -Wpartial-fields -Wno-partial-fields -Wpartial-type-signatures -Wno-partial-type-signatures -Wredundant-constraints -Wno-redundant-constraints -Wredundant-record-wildcards -Wno-redundant-record-wildcards -Wsafe -Wno-safe -Wsemigroup -Wno-semigroup -Wsimplifiable-class-constraints -Wno-simplifiable-class-constraints -Wspace-after-bang -Wno-missing-space-after-bang -Wstar-binder -Wno-star-binder -Wstar-is-type -Wno-star-is-type -Wtabs -Wno-tabs -Wtrustworthy-safe -Wno-safe -Wtype-defaults -Wno-type-defaults -Wtyped-holes -Wno-typed-holes -Wunbanged-strict-patterns -Wno-unbanged-strict-patterns -Wunrecognised-pragmas -Wno-unrecognised-pragmas -Wunrecognised-warning-flags -Wno-unrecognised-warning-flags -Wunsafe -Wno-unsafe -Wunsupported-calling-conventions -Wno-unsupported-calling-conventions -Wunsupported-llvm-version -Wno-monomorphism-restriction -Wunticked-promoted-constructors -Wno-unticked-promoted-constructors -Wunused-binds -Wno-unused-binds -Wunused-do-bind -Wno-unused-do-bind -Wunused-foralls -Wno-unused-foralls -Wunused-imports -Wno-unused-imports -Wunused-local-binds -Wno-unused-local-binds -Wunused-matches -Wno-unused-matches -Wunused-packages -Wno-unused-packages -Wunused-pattern-binds -Wno-unused-pattern-binds -Wunused-record-wildcards -Wno-unused-record-wildcards -Wunused-top-binds -Wno-unused-top-binds -Wunused-type-patterns -Wno-unused-type-patterns -Wwarn -Werror -Wwarnings-deprecations -Wno-warnings-deprecations -Wwrong-do-bind -Wno-wrong-do-bind

  Code generation

-dynamic-too
    Build dynamic object files as well as static object files during compilation

-fasm
    Use the native code generator

-fbyte-code
    Generate byte-code

-fexternal-dynamic-refs
    Generate code for linking against dynamic libraries

-fllvm
    Compile using the LLVM code generator

-fno-code
    Omit code generation

-fobject-code
    Generate object code

-fPIC
    Generate position-independent code (where available)

-fPIE
    Generate code for a position-independent executable (where available)

-fwrite-interface
    Always write interface files

  Debugging the compiler

-dcmm-lint
    C-\- pass sanity checking

-dcore-lint
    Turn on internal sanity checking

-ddump-asm
    Dump final assembly

-ddump-asm-expanded
    Dump the result of the synthetic instruction expansion pass.

-ddump-asm-liveness
    Dump assembly augmented with register liveness

-ddump-asm-native
    Dump initial assembly

-ddump-asm-regalloc
    Dump the result of register allocation

-ddump-asm-regalloc-stages
    Dump the build/spill stages of the -fregs-graph register allocator.

-ddump-asm-stats
    Dump statistics from the register allocator.

-ddump-bcos
    Dump interpreter byte code

-ddump-cfg-weights
    Dump the assumed weights of the CFG.

-ddump-cmm
    Dump the final C-\- output

-ddump-cmm-caf
    Dump the results of the C-\- CAF analysis pass.

-ddump-cmm-cbe
    Dump the results of common block elimination

-ddump-cmm-cfg
    Dump the results of the C-\- control flow optimisation pass.

-ddump-cmm-cps
    Dump the results of the CPS pass

-ddump-cmm-from-stg
    Dump STG-to-C-\- output

-ddump-cmm-info
    Dump the results of the C-\- info table augmentation pass.

-ddump-cmm-proc
    Dump the results of proc-point analysis

-ddump-cmm-procmap
    Dump the results of the C-\- proc-point map pass.

-ddump-cmm-raw
    Dump raw C-\-

-ddump-cmm-sink
    Dump the results of the C-\- sinking pass.

-ddump-cmm-sp
    Dump the results of the C-\- stack layout pass.

-ddump-cmm-split
    Dump the results of the C-\- proc-point splitting pass.

-ddump-cmm-switch
    Dump the results of switch lowering passes

-ddump-cmm-verbose
    Write output from main C-\- pipeline passes to files

-ddump-cmm-verbose-by-proc
    Show output from main C-\- pipeline passes (grouped by proc)

-ddump-core-stats
    Print a one-line summary of the size of the Core program at the end of the optimisation pipeline

-ddump-cse
    Dump CSE output

-ddump-deriv
    Dump deriving output

-ddump-ds
    Dump desugarer output.

-ddump-ec-trace
    Trace exhaustiveness checker

-ddump-file-prefix=⟨str⟩
    Set the prefix of the filenames used for debugging output.

-ddump-foreign
    Dump foreign export stubs

-ddump-hpc
    An alias for -ddump-ticked.

-ddump-if-trace
    Trace interface files

-ddump-inlinings
    Dump inlining info

-ddump-json
    Dump error messages as JSON documents

-ddump-llvm
    Dump LLVM intermediate code.

-ddump-mod-map
    Dump the state of the module mapping database.

-ddump-occur-anal
    Dump occurrence analysis output

-ddump-opt-cmm
    Dump the results of C-\- to C-\- optimising passes

-ddump-parsed
    Dump parse tree

-ddump-parsed-ast
    Dump parser output as a syntax tree

-ddump-prep
    Dump prepared core

-ddump-rn
    Dump renamer output

-ddump-rn-ast
    Dump renamer output as a syntax tree

-ddump-rn-stats
    Renamer stats

-ddump-rn-trace
    Trace renamer

-ddump-rtti
    Trace runtime type inference

-ddump-rule-firings
    Dump rule firing info

-ddump-rule-rewrites
    Dump detailed rule firing info

-ddump-rules
    Dump rewrite rules

-ddump-simpl
    Dump final simplifier output

-ddump-simpl-iterations
    Dump output from each simplifier iteration

-ddump-simpl-stats
    Dump simplifier stats

-ddump-spec
    Dump specialiser output

-ddump-splices
    Dump TH spliced expressions, and what they evaluate to

-ddump-stg
    Show CoreToStg output

-ddump-stg-final
    Show output of last STG pass.

-ddump-stg-unarised
    Show unarised STG

-ddump-str-signatures
    Dump strictness signatures

-ddump-stranal
    Dump strictness analyser output

-ddump-tc
    Dump typechecker output

-ddump-tc-ast
    Dump typechecker output as a syntax tree

-ddump-tc-trace
    Trace typechecker

-ddump-ticked
    Dump the code instrumented by HPC (hpc).

-ddump-timings
    Dump per-pass timing and allocation statistics

-ddump-to-file
    Dump to files instead of stdout

-ddump-types
    Dump type signatures

-ddump-worker-wrapper
    Dump worker-wrapper output

-dfaststring-stats
    Show statistics for fast string usage when finished

-dhex-word-literals
    Print values of type Word# in hexadecimal.

-dinitial-unique=⟨s⟩
    Start UniqSupply allocation from ⟨s⟩.

-dinline-check=⟨str⟩
    Dump information about inlining decisions

-dno-debug-output
    Suppress unsolicited debugging output

-dno-typeable-binds
    Don't generate bindings for Typeable methods

-dppr-case-as-let
    Print single alternative case expressions as strict lets.

-dppr-cols=⟨n⟩
    Set the width of debugging output. For example -dppr-cols200

-dppr-debug
    Turn on debug printing (more verbose)

-dppr-user-length
    Set the depth for printing expressions in error msgs

-drule-check=⟨str⟩
    Dump information about potential rule application

-dshow-passes
    Print out each pass name as it happens

-dstg-lint
    STG pass sanity checking

-dsuppress-all
    In dumps, suppress everything (except for uniques) that is suppressible.

-dsuppress-coercions
    Suppress the printing of coercions in Core dumps to make them shorter

-dsuppress-idinfo
    Suppress extended information about identifiers where they are bound

-dsuppress-module-prefixes
    Suppress the printing of module qualification prefixes

-dsuppress-stg-free-vars
    Suppress the printing of closure free variable lists in STG output

-dsuppress-ticks
    Suppress "ticks" in the pretty-printer output.

-dsuppress-timestamps
    Suppress timestamps in dumps

-dsuppress-type-applications
    Suppress type applications

-dsuppress-type-signatures
    Suppress type signatures

-dsuppress-unfoldings
    Suppress the printing of the stable unfolding of a variable at its binding site

-dsuppress-uniques
    Suppress the printing of uniques in debug output (easier to use diff)

-dsuppress-var-kinds
    Suppress the printing of variable kinds

-dth-dec-file
    Dump evaluated TH declarations into *.th.hs files

-dunique-increment=⟨i⟩
    Set the increment for the generated Unique's to ⟨i⟩.

-dverbose-core2core
    Show output from each core-to-core pass

-dverbose-stg2stg
    Show output from each STG-to-STG pass

-falignment-sanitisation
    Compile with alignment checks for all info table dereferences.

-fcatch-bottoms
    Insert error expressions after bottoming expressions; useful when debugging the compiler.

-fllvm-fill-undef-with-garbage
    Intruct LLVM to fill dead STG registers with garbage

-fproc-alignment
    Align functions at given boundary.

-g  Produce DWARF debug information in compiled object files. ⟨n⟩ can be 0, 1, or 2, with higher numbers producing richer output. If ⟨n⟩ is omitted, level 2 is assumed.

  C pre-processor

-cpp
    Run the C pre-processor on Haskell source files

-D⟨symbol⟩[=⟨value⟩]
    Define a symbol in the C pre-processor

-I⟨dir⟩
    Add ⟨dir⟩ to the directory search list for #include files

-U⟨symbol⟩
    Undefine a symbol in the C pre-processor

  Finding imports

-i  Empty the import directory list

-i⟨dir⟩[:⟨dir⟩]*
    add ⟨dir⟩, ⟨dir2⟩, etc. to import path

  Interactive mode

-fbreak-on-error
    Break on uncaught exceptions and errors

-fbreak-on-exception
    Break on any exception thrown

-fghci-hist-size=⟨n⟩
    Set the number of entries GHCi keeps for :history. See ghci-debugger.

-fghci-leak-check
    (Debugging only) check for space leaks when loading new modules in GHCi.

-flocal-ghci-history
    Use current directory for the GHCi command history file .ghci-history.

-fno-it
    No longer set the special variable it.

-fprint-bind-result
    Turn on printing of binding results in GHCi

-fprint-evld-with-show
    Instruct :print to use Show instances where possible.

-fshow-loaded-modules
    Show the names of modules that GHCi loaded after a :load command.

-ghci-script
    Read additional .ghci files

-ignore-dot-ghci
    Disable reading of .ghci files

-interactive-print ⟨name⟩
    Select the function to use for printing evaluated expressions in GHCi

  Interface files

--show-iface ⟨file⟩
    See modes.

-ddump-hi
    Dump the new interface to stdout

-ddump-hi-diffs
    Show the differences vs. the old interface

-ddump-minimal-imports
    Dump a minimal set of imports

  Keeping intermediate files

-keep-hc-file
    Retain intermediate .hc files.

-keep-hi-files
    Retain intermediate .hi files (the default).

-keep-hscpp-file
    Retain intermediate .hscpp files.

-keep-llvm-file
    Retain intermediate LLVM .ll files. Implies -fllvm.

-keep-o-files
    Retain intermediate .o files (the default).

-keep-s-file
    Retain intermediate .s files.

-keep-tmp-files
    Retain all intermediate temporary files.

  Language options

-fno-safe-haskell
    Disable Safe Haskell

-fsort-by-size-hole-fits
    Sort valid hole fits by size.

-fsort-by-subsumption-hole-fits
    Sort valid hole fits by subsumption.

-Winferred-safe-imports
    warn when an explicitly Safe Haskell module imports a Safe-Inferred one

-Wmissing-safe-haskell-mode
    warn when the Safe Haskell mode is not explicitly specified.

-XAllowAmbiguousTypes
    Allow the user to write ambiguous types, and the type inference engine to infer them.

-XApplicativeDo
    Enable Applicative do-notation desugaring

-XArrows
    Enable arrow notation extension

-XBangPatterns
    Enable bang patterns.

-XBinaryLiterals
    Enable support for binary literals.

-XBlockArguments
    Allow do blocks and other constructs as function arguments.

-XCApiFFI
    Enable the CAPI calling convention.

-XConstrainedClassMethods
    Enable constrained class methods.

-XConstraintKinds
    Enable a kind of constraints.

-XCPP
    Enable the C preprocessor.

-XCUSKs
    Enable detection of complete user-supplied kind signatures.

-XDataKinds
    Enable datatype promotion.

-XDatatypeContexts
    Allow contexts on data types.

-XDefaultSignatures
    Enable default signatures.

-XDeriveAnyClass
    Enable deriving for any class.

-XDeriveDataTypeable
    Enable deriving for the Data class. Implied by (deprecated) AutoDeriveTypeable.

-XDeriveFoldable
    Enable deriving for the Foldable class. Implied by DeriveTraversable.

-XDeriveFunctor
    Enable deriving for the Functor class. Implied by DeriveTraversable.

-XDeriveGeneric
    Enable deriving for the Generic class.

-XDeriveLift
    Enable deriving for the Lift class

-XDeriveTraversable
    Enable deriving for the Traversable class. Implies DeriveFunctor and DeriveFoldable.

-XDerivingStrategies
    Enables deriving strategies.

-XDerivingVia
    Enable deriving instances via types of the same runtime representation. Implies DerivingStrategies.

-XDisambiguateRecordFields
    Enable record field disambiguation. Implied by RecordWildCards.

-XDuplicateRecordFields
    Allow definition of record types with identically-named fields.

-XEmptyCase
    Allow empty case alternatives.

-XEmptyDataDecls
    Allow definition of empty data types.

-XEmptyDataDeriving
    Allow deriving instances of standard type classes for empty data types.

-XExistentialQuantification
    Enable liberalised type synonyms.

-XExplicitForAll
    Enable explicit universal quantification. Implied by ScopedTypeVariables, LiberalTypeSynonyms, RankNTypes and ExistentialQuantification.

-XExplicitNamespaces
    Enable using the keyword type to specify the namespace of entries in imports and exports (explicit-namespaces). Implied by TypeOperators and TypeFamilies.

-XExtendedDefaultRules
    Use GHCi's extended default rules in a normal module.

-XFlexibleContexts
    Enable flexible contexts.

-XFlexibleInstances
    Enable flexible instances. Implies TypeSynonymInstances.

-XForeignFunctionInterface
    Enable foreign function interface.

-XFunctionalDependencies
    Enable functional dependencies. Implies MultiParamTypeClasses.

-XGADTs
    Enable generalised algebraic data types. Implies GADTSyntax and MonoLocalBinds.

-XGADTSyntax
    Enable generalised algebraic data type syntax.

-XGeneralisedNewtypeDeriving
    Enable newtype deriving.

-XGeneralizedNewtypeDeriving
    Enable newtype deriving.

-XHaskell2010
    Use the Haskell 2010 language variant.

-XHaskell98
    Use the Haskell 2010 language variant.

-XHexFloatLiterals
    Enable support for hexadecimal floating point literals.

-XImplicitParams
    Enable Implicit Parameters.

-XImportQualifiedPost
    ImportQualifiedPost allows the syntax import M qualified

-XImpredicativeTypes
    Enable impredicative types. Implies RankNTypes.

-XIncoherentInstances
    Enable incoherent instances. Implies OverlappingInstances.

-XInstanceSigs
    Enable instance signatures.

-XInterruptibleFFI
    Enable interruptible FFI.

-XKindSignatures
    Enable kind signatures. Implied by TypeFamilies and PolyKinds.

-XLambdaCase
    Enable lambda-case expressions.

-XLiberalTypeSynonyms
    Enable liberalised type synonyms.

-XMagicHash
    Allow # as a postfix modifier on identifiers.

-XMonadComprehensions
    Enable monad comprehensions.

-XMonadFailDesugaring
    Enable monadfail desugaring.

-XMonoLocalBinds
    Enable do not generalise local bindings. Implied by TypeFamilies and GADTs.

-XMultiParamTypeClasses
    Enable multi parameter type classes. Implied by FunctionalDependencies.

-XMultiWayIf
    Enable multi-way if-expressions.

-XNamedFieldPuns
    Enable record puns.

-XNamedWildCards
    Enable named wildcards.

-XNegativeLiterals
    Enable support for negative literals.

-XNoImplicitPrelude
    Don't implicitly import Prelude. Implied by RebindableSyntax.

-XNoMonomorphismRestriction
    Disable the monomorphism restriction.

-XNondecreasingIndentation
    Allow nested contexts to be at the same indentation level as its enclosing context.

-XNoPatternGuards
    Disable pattern guards. Implied by Haskell98.

-XNoTraditionalRecordSyntax
    Disable support for traditional record syntax (as supported by Haskell 98) C {f = x}

-XNPlusKPatterns
    Enable support for n+k patterns. Implied by Haskell98.

-XNullaryTypeClasses
    Deprecated, does nothing. nullary (no parameter) type classes are now enabled using MultiParamTypeClasses.

-XNumDecimals
    Enable support for 'fractional' integer literals.

-XNumericUnderscores
    Enable support for numeric underscores.

-XOverlappingInstances
    Enable overlapping instances.

-XOverloadedLabels
    Enable overloaded labels.

-XOverloadedLists
    Enable overloaded lists.

-XOverloadedStrings
    Enable overloaded string literals.

-XPackageImports
    Enable package-qualified imports.

-XParallelListComp
    Enable parallel list comprehensions.

-XPartialTypeSignatures
    Enable partial type signatures.

-XPatternSynonyms
    Enable pattern synonyms.

-XPolyKinds
    Enable kind polymorphism. Implies KindSignatures.

-XPostfixOperators
    Enable postfix operators.

-XQuantifiedConstraints
    Allow forall quantifiers in constraints.

-XQuasiQuotes
    Enable quasiquotation.

-XRank2Types
    Enable rank-2 types. Synonym for RankNTypes.

-XRankNTypes
    Enable rank-N types. Implied by ImpredicativeTypes.

-XRebindableSyntax
    Employ rebindable syntax. Implies NoImplicitPrelude.

-XRecordWildCards
    Enable record wildcards. Implies DisambiguateRecordFields.

-XRecursiveDo
    Enable recursive do (mdo) notation.

-XRoleAnnotations
    Enable role annotations.

-XSafe
    Enable the Safe Haskell Safe mode.

-XScopedTypeVariables
    Enable lexically-scoped type variables.

-XStandaloneDeriving
    Enable standalone deriving.

-XStandaloneKindSignatures
    Allow the use of standalone kind signatures.

-XStarIsType
    Treat * as Data.Kind.Type.

-XStaticPointers
    Enable static pointers.

-XStrict
    Make bindings in the current module strict by default.

-XStrictData
    Enable default strict datatype fields.

-XTemplateHaskell
    Enable Template Haskell.

-XTemplateHaskellQuotes
    Enable quotation subset of Template Haskell.

-XTransformListComp
    Enable generalised list comprehensions.

-XTrustworthy
    Enable the Safe Haskell Trustworthy mode.

-XTupleSections
    Enable tuple sections.

-XTypeApplications
    Enable type application syntax in terms and types.

-XTypeFamilies
    Enable type families. Implies ExplicitNamespaces, KindSignatures, and MonoLocalBinds.

-XTypeFamilyDependencies
    Enable injective type families. Implies TypeFamilies.

-XTypeInType
    Deprecated. Enable kind polymorphism and datatype promotion.

-XTypeOperators
    Enable type operators. Implies ExplicitNamespaces.

-XTypeSynonymInstances
    Enable type synonyms in instance heads. Implied by FlexibleInstances.

-XUnboxedSums
    Enable unboxed sums.

-XUnboxedTuples
    Enable the use of unboxed tuple syntax.

-XUndecidableInstances
    Enable undecidable instances.

-XUndecidableSuperClasses
    Allow all superclass constraints, including those that may result in non-termination of the typechecker.

-XUnicodeSyntax
    Enable unicode syntax.

-XUnliftedFFITypes
    Enable unlifted FFI types

-XUnliftedNewtypes
    Enable unlifted newtypes.

-XUnsafe
    Enable Safe Haskell Unsafe mode.

-XViewPatterns
    Enable view patterns.

  Linking options

-c  Stop after generating object (.o) file

-debug
    Use the debugging runtime

-dylib-install-name ⟨path⟩
    Set the install name (via -install_name passed to Apple's linker), specifying the full install path of the library file. Any libraries or executables that link with it later will pick up that path as their runtime search location for it. (Darwin/OS X only)

-dynamic
    Build dynamically-linked object files and executables

-dynload
    Selects one of a number of modes for finding shared libraries at runtime.

-eventlog
    Enable runtime event tracing

-fno-embed-manifest
    Do not embed the manifest in the executable (Windows only)

-fno-gen-manifest
    Do not generate a manifest file (Windows only)

-fno-shared-implib
    Don't generate an import library for a DLL (Windows only)

-framework ⟨name⟩
    On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This option corresponds to the -framework option for Apple's Linker.

-framework-path ⟨dir⟩
    On Darwin/OS X/iOS only, add ⟨dir⟩ to the list of directories searched for frameworks. This option corresponds to the -F option for Apple's Linker.

-fwhole-archive-hs-libs
    When linking a binary executable, this inserts the flag -Wl,--whole-archive before any -l flags for Haskell libraries, and -Wl,--no-whole-archive afterwards

-keep-cafs
    Do not garbage-collect CAFs (top-level expressions) at runtime

-L ⟨dir⟩
    Add ⟨dir⟩ to the list of directories searched for libraries

-l ⟨lib⟩
    Link in library ⟨lib⟩

-main-is ⟨thing⟩
    Set main module and function

-no-hs-main
    Don't assume this program contains main

-no-rtsopts-suggestions
    Don't print RTS suggestions about linking with -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩].

-package ⟨name⟩
    Expose package ⟨pkg⟩

-pie
    Instruct the linker to produce a position-independent executable.

-rdynamic
    This instructs the linker to add all symbols, not only used ones, to the dynamic symbol table. Currently Linux and Windows/MinGW32 only. This is equivalent to using -optl -rdynamic on Linux, and -optl -export-all-symbols on Windows.

-rtsopts[=⟨none|some|all|ignore|ignoreAll⟩]
    Control whether the RTS behaviour can be tweaked via command-line flags and the GHCRTS environment variable. Using none means no RTS flags can be given; some means only a minimum of safe options can be given (the default); all (or no argument at all) means that all RTS flags are permitted; ignore means RTS flags can be given, but are treated as regular arguments and passed to the Haskell program as arguments; ignoreAll is the same as ignore, but GHCRTS is also ignored. -rtsopts does not affect -with-rtsopts behavior; flags passed via -with-rtsopts are used regardless of -rtsopts.

-shared
    Generate a shared library (as opposed to an executable)

-split-sections
    Split sections for link-time dead-code stripping

-static
    Use static Haskell libraries

-staticlib
    Generate a standalone static library (as opposed to an executable). This is useful when cross compiling. The library together with all its dependencies ends up in in a single static library that can be linked against.

-threaded
    Use the threaded runtime

-with-rtsopts=⟨opts⟩
    Set the default RTS options to ⟨opts⟩.

  Miscellaneous options

-fexternal-interpreter
    Run interpreted code in a separate process

-fglasgow-exts
    Deprecated. Enable most language extensions; see options-language for exactly which ones.

-ghcversion-file ⟨path to ghcversion.h⟩
    (GHC as a C compiler only) Use this ghcversion.h file

-H ⟨size⟩
    Set the minimum size of the heap to ⟨size⟩

-j[⟨n⟩]
    When compiling with --make, compile ⟨n⟩ modules in parallel.

  Modes of operation

--frontend ⟨module⟩
    run GHC with the given frontend plugin; see frontend_plugins for details.

--help
    Display help

--info
    display information about the compiler

--interactive
    Interactive mode - normally used by just running ghci; see ghci for details.

--make
    Build a multi-module Haskell program, automatically figuring out dependencies. Likely to be much easier, and faster, than using make; see make-mode for details.

--mk-dll
    DLL-creation mode (Windows only)

--numeric-version
    display GHC version (numeric only)

--print-libdir
    display GHC library directory

--show-iface ⟨file⟩
    display the contents of an interface file.

--show-options
    display the supported command line options

--supported-extensions
    display the supported language extensions

--version
    display GHC version

-e ⟨expr⟩
    Evaluate expr; see eval-mode for details.

-M  generate dependency information suitable for use in a Makefile; see makefile-dependencies for details.

  Individual optimizations

-fasm-shortcutting
    Enable shortcutting on assembly. Implied by -O2.

-fbinary-blob-threshold=⟨n⟩
    default: 500K. Tweak assembly generator for binary blobs.

-fblock-layout-cfg
    Use the new cfg based block layout algorithm.

-fblock-layout-weightless
    Ignore cfg weights for code layout.

-fblock-layout-weights
    Sets edge weights used by the new code layout algorithm.

-fcall-arity
    Enable call-arity optimisation. Implied by -O.

-fcase-folding
    Enable constant folding in case expressions. Implied by -O.

-fcase-merge
    Enable case-merging. Implied by -O.

-fcmm-elim-common-blocks
    Enable Cmm common block elimination. Implied by -O.

-fcmm-sink
    Enable Cmm sinking. Implied by -O.

-fcpr-anal
    Turn on CPR analysis in the demand analyser. Implied by -O.

-fcross-module-specialise
    Turn on specialisation of overloaded functions imported from other modules.

-fcse
    Enable common sub-expression elimination. Implied by -O.

-fdicts-cheap
    Make dictionary-valued expressions seem cheap to the optimiser.

-fdicts-strict
    Make dictionaries strict

-fdmd-tx-dict-sel
    Use a special demand transformer for dictionary selectors. Always enabled by default.

-fdo-eta-reduction
    Enable eta-reduction. Implied by -O.

-fdo-lambda-eta-expansion
    Enable lambda eta-expansion. Always enabled by default.

-feager-blackholing
    Turn on eager blackholing

-fenable-rewrite-rules
    Switch on all rewrite rules (including rules generated by automatic specialisation of overloaded functions). Implied by -O.

-fexcess-precision
    Enable excess intermediate precision

-fexitification
    Enables exitification optimisation. Implied by -O.

-fexpose-all-unfoldings
    Expose all unfoldings, even for very large or recursive functions.

-ffloat-in
    Turn on the float-in transformation. Implied by -O.

-ffull-laziness
    Turn on full laziness (floating bindings outwards). Implied by -O.

-ffun-to-thunk
    Allow worker-wrapper to convert a function closure into a thunk if the function does not use any of its arguments. Off by default.

-fignore-asserts
    Ignore assertions in the source. Implied by -O.

-fignore-interface-pragmas
    Ignore pragmas in interface files. Implied by -O0 only.

-flate-dmd-anal
    Run demand analysis again, at the end of the simplification pipeline

-flate-specialise
    Run a late specialisation pass

-fliberate-case
    Turn on the liberate-case transformation. Implied by -O2.

-fliberate-case-threshold=⟨n⟩
    default: 2000. Set the size threshold for the liberate-case transformation to ⟨n⟩

-fllvm-pass-vectors-in-regs
    Pass vector value in vector registers for function calls

-floopification
    Turn saturated self-recursive tail-calls into local jumps in the generated assembly. Implied by -O.

-fmax-inline-alloc-size=⟨n⟩
    default: 128. Set the maximum size of inline array allocations to ⟨n⟩ bytes (default: 128).

-fmax-inline-memcpy-insns=⟨n⟩
    default: 32. Inline memcpy calls if they would generate no more than ⟨n⟩ pseudo instructions.

-fmax-inline-memset-insns=⟨n⟩
    default: 32. Inline memset calls if they would generate no more than ⟨n⟩ pseudo instructions

-fmax-simplifier-iterations=⟨n⟩
    default: 4. Set the max iterations for the simplifier.

-fmax-uncovered-patterns=⟨n⟩
    default: 4. Set the maximum number of patterns to display in warnings about non-exhaustive ones.

-fmax-worker-args=⟨n⟩
    default: 10. If a worker has that many arguments, none will be unpacked anymore.

-fno-opt-coercion
    Turn off the coercion optimiser

-fno-pre-inlining
    Turn off pre-inlining

-fno-state-hack
    Turn off the state hackwhereby any lambda with a real-world state token as argument is considered to be single-entry. Hence OK to inline things inside it.

-fomit-interface-pragmas
    Don't generate interface pragmas. Implied by -O0 only.

-fomit-yields
    Omit heap checks when no allocation is being performed.

-foptimal-applicative-do
    Use a slower but better algorithm for ApplicativeDo

-fpedantic-bottoms
    Make GHC be more precise about its treatment of bottom (but see also -fno-state-hack). In particular, GHC will not eta-expand through a case expression.

-fregs-graph
    Use the graph colouring register allocator for register allocation in the native code generator. Implied by -O2.

-fregs-iterative
    Use the iterative coalescing graph colouring register allocator in the native code generator.

-fsimpl-tick-factor=⟨n⟩
    default: 100. Set the percentage factor for simplifier ticks.

-fsimplifier-phases=⟨n⟩
    default: 2. Set the number of phases for the simplifier. Ignored with -O0.

-fsolve-constant-dicts
    When solving constraints, try to eagerly solve super classes using available dictionaries.

-fspec-constr
    Turn on the SpecConstr transformation. Implied by -O2.

-fspec-constr-count=⟨n⟩
    default: 3.* Set to ⟨n⟩ the maximum number of specialisations that will be created for any one function by the SpecConstr transformation.

-fspec-constr-keen
    Specialize a call with an explicit constructor argument, even if the argument is not scrutinised in the body of the function

-fspec-constr-threshold=⟨n⟩
    default: 2000. Set the size threshold for the SpecConstr transformation to ⟨n⟩.

-fspecialise
    Turn on specialisation of overloaded functions. Implied by -O.

-fspecialise-aggressively
    Turn on specialisation of overloaded functions regardless of size, if unfolding is available

-fstatic-argument-transformation
    Turn on the static argument transformation.

-fstg-cse
    Enable common sub-expression elimination on the STG intermediate language

-fstg-lift-lams
    Enable late lambda lifting on the STG intermediate language. Implied by -O2.

-fstg-lift-lams-known
    Allow turning known into unknown calls while performing late lambda lifting.

-fstg-lift-lams-non-rec-args
    Create top-level non-recursive functions with at most <n> parameters while performing late lambda lifting.

-fstg-lift-lams-rec-args
    Create top-level recursive functions with at most <n> parameters while performing late lambda lifting.

-fstrictness
    Turn on strictness analysis. Implied by -O. Implies -fworker-wrapper

-fstrictness-before=⟨n⟩
    Run an additional strictness analysis before simplifier phase ⟨n⟩

-funbox-small-strict-fields
    Flatten strict constructor fields with a pointer-sized representation. Implied by -O.

-funbox-strict-fields
    Flatten strict constructor fields

-funfolding-creation-threshold=⟨n⟩
    default: 750. Tweak unfolding settings.

-funfolding-dict-discount=⟨n⟩
    default: 30. Tweak unfolding settings.

-funfolding-fun-discount=⟨n⟩
    default: 60. Tweak unfolding settings.

-funfolding-keeness-factor=⟨n⟩
    default: 1.5. Tweak unfolding settings.

-funfolding-use-threshold=⟨n⟩
    default: 60. Tweak unfolding settings.

-fworker-wrapper
    Enable the worker-wrapper transformation.

  Optimization levels

-O  Enable level 1 optimisations

-O0 Disable optimisations (default)

-O2 Enable level 2 optimisations

-O⟨n⟩
    Any -On where n > 2 is the same as -O2.

  Package options

-clear-package-db
    Clear the package db stack.

-distrust ⟨pkg⟩
    Expose package ⟨pkg⟩ and set it to be distrusted. See safe-haskell.

-distrust-all-packages
    Distrust all packages by default. See safe-haskell.

-fpackage-trust
    Enable Safe Haskell trusted package requirement for trustworthy modules.

-global-package-db
    Add the global package db to the stack.

-hide-all-packages
    Hide all packages by default

-hide-package ⟨pkg⟩
    Hide package ⟨pkg⟩

-ignore-package ⟨pkg⟩
    Ignore package ⟨pkg⟩

-no-auto-link-packages
    Don't automatically link in the base and rts packages.

-no-global-package-db
    Remove the global package db from the stack.

-no-user-package-db
    Remove the user's package db from the stack.

-package ⟨pkg⟩
    Expose package ⟨pkg⟩

-package-db ⟨file⟩
    Add ⟨file⟩ to the package db stack.

-package-env ⟨file⟩|⟨name⟩
    Use the specified package environment.

-package-id ⟨unit-id⟩
    Expose package by id ⟨unit-id⟩

-this-unit-id ⟨unit-id⟩
    Compile to be part of unit (i.e. package) ⟨unit-id⟩

-trust ⟨pkg⟩
    Expose package ⟨pkg⟩ and set it to be trusted. See safe-haskell.

-user-package-db
    Add the user's package db to the stack.

  Phases of compilation

-C  Stop after generating C (.hc file)

-c  Stop after generating object (.o) file

-E  Stop after preprocessing (.hspp file)

-F  Enable the use of a pre-processor (set with -pgmF ⟨cmd⟩)

-S  Stop after generating assembly (.s file)

-x ⟨suffix⟩
    Override default behaviour for source files

  Overriding external programs

-pgma ⟨cmd⟩
    Use ⟨cmd⟩ as the assembler

-pgmc ⟨cmd⟩
    Use ⟨cmd⟩ as the C compiler

-pgmdll ⟨cmd⟩
    Use ⟨cmd⟩ as the DLL generator

-pgmF ⟨cmd⟩
    Use ⟨cmd⟩ as the pre-processor (with -F only)

-pgmi ⟨cmd⟩
    Use ⟨cmd⟩ as the external interpreter command.

-pgmL ⟨cmd⟩
    Use ⟨cmd⟩ as the literate pre-processor

-pgml ⟨cmd⟩
    Use ⟨cmd⟩ as the linker

-pgmlc ⟨cmd⟩
    Use ⟨cmd⟩ as the LLVM compiler

-pgmlibtool ⟨cmd⟩
    Use ⟨cmd⟩ as the command for libtool (with -staticlib only).

-pgmlo ⟨cmd⟩
    Use ⟨cmd⟩ as the LLVM optimiser

-pgmP ⟨cmd⟩
    Use ⟨cmd⟩ as the C pre-processor (with -cpp only)

-pgms ⟨cmd⟩
    Use ⟨cmd⟩ as the splitter

-pgmwindres ⟨cmd⟩
    Use ⟨cmd⟩ as the program for embedding manifests on Windows.

  Phase-specific options

-opta ⟨option⟩
    pass ⟨option⟩ to the assembler

-optc ⟨option⟩
    pass ⟨option⟩ to the C compiler

-optcxx ⟨option⟩
    pass ⟨option⟩ to the C++ compiler

-optdll ⟨option⟩
    pass ⟨option⟩ to the DLL generator

-optF ⟨option⟩
    pass ⟨option⟩ to the custom pre-processor

-opti ⟨option⟩
    pass ⟨option⟩ to the interpreter sub-process.

-optL ⟨option⟩
    pass ⟨option⟩ to the literate pre-processor

-optl ⟨option⟩
    pass ⟨option⟩ to the linker

-optlc ⟨option⟩
    pass ⟨option⟩ to the LLVM compiler

-optlo ⟨option⟩
    pass ⟨option⟩ to the LLVM optimiser

-optP ⟨option⟩
    pass ⟨option⟩ to cpp (with -cpp only)

-optwindres ⟨option⟩
    pass ⟨option⟩ to windres.

  Platform-specific options

-mbmi2
    (x86 only) Use BMI2 for bit manipulation operations

-msse2
    (x86 only) Use SSE2 for floating-point operations

-msse4.2
    (x86 only) Use SSE4.2 for floating-point operations

  Compiler plugins

-fclear-plugins
    Clear the list of active plugins

-fplugin-opt=⟨module⟩:⟨args⟩
    Give arguments to a plugin module; module must be specified with -fplugin=⟨module⟩

-fplugin-trustworthy
    Trust the used plugins and no longer mark the compiled module as unsafe

-fplugin=⟨module⟩
    Load a plugin exported by a given module

-hide-all-plugin-packages
    Hide all packages for plugins by default

-plugin-package ⟨pkg⟩
    Expose ⟨pkg⟩ for plugins

-plugin-package-id ⟨pkg-id⟩
    Expose ⟨pkg-id⟩ for plugins

  Profiling

-fno-prof-auto
    Disables any previous -fprof-auto, -fprof-auto-top, or -fprof-auto-exported options.

-fno-prof-cafs
    Disables any previous -fprof-cafs option.

-fno-prof-count-entries
    Do not collect entry counts

-fprof-auto
    Auto-add SCC\ s to all bindings not marked INLINE

-fprof-auto-calls
    Auto-add SCC\ s to all call sites

-fprof-auto-exported
    Auto-add SCC\ s to all exported bindings not marked INLINE

-fprof-auto-top
    Auto-add SCC\ s to all top-level bindings not marked INLINE

-fprof-cafs
    Auto-add SCC\ s to all CAFs

-prof
    Turn on profiling

-ticky
    Turn on ticky-ticky profiling

  Program coverage

-fhpc
    Turn on Haskell program coverage instrumentation

  Recompilation checking

-fforce-recomp
    Turn off recompilation checking. This is implied by any -ddump-X option when compiling a single file (i.e. when using -c).

-fignore-hpc-changes
    Do not recompile modules just to match changes to HPC flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi.

-fignore-optim-changes
    Do not recompile modules just to match changes to optimisation flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi.

  Redirecting output

--exclude-module=⟨file⟩
    Regard ⟨file⟩ as "stable"; i.e., exclude it from having dependencies on it.

-ddump-mod-cycles
    Dump module cycles

-dep-makefile ⟨file⟩
    Use ⟨file⟩ as the makefile

-dep-suffix ⟨suffix⟩
    Make dependencies that declare that files with suffix .⟨suf⟩⟨osuf⟩ depend on interface files with suffix .⟨suf⟩hi

-dumpdir ⟨dir⟩
    redirect dump files

-hcsuf ⟨suffix⟩
    set the suffix to use for intermediate C files

-hidir ⟨dir⟩
    set directory for interface files

-hiedir ⟨dir⟩
    set directory for extended interface files

-hiesuf ⟨suffix⟩
    set the suffix to use for extended interface files

-hisuf ⟨suffix⟩
    set the suffix to use for interface files

-include-cpp-deps
    Include preprocessor dependencies

-include-pkg-deps
    Regard modules imported from packages as unstable

-o ⟨file⟩
    set output filename

-odir ⟨dir⟩
    set directory for object files

-ohi ⟨file⟩
    set the filename in which to put the interface

-osuf ⟨suffix⟩
    set the output file suffix

-outputdir ⟨dir⟩
    set output directory

-stubdir ⟨dir⟩
    redirect FFI stub files

  Temporary files

-tmpdir ⟨dir⟩
    set the directory for temporary files

  Verbosity options

-fabstract-refinement-hole-fits
    default: off. Toggles whether refinements where one or more of the holes are abstract are reported.

-fdefer-diagnostics
    Defer and group diagnostic messages by severity

-fdiagnostics-color=⟨always|auto|never⟩
    Use colors in error messages

-fdiagnostics-show-caret
    Whether to show snippets of original source code

-ferror-spans
    Output full span in error messages

-fhide-source-paths
    hide module source and object paths

-fkeep-going
    Continue compilation as far as possible on errors

-fmax-refinement-hole-fits=⟨n⟩
    default: 6. Set the maximum number of refinement hole fits for typed holes to display in type error messages.

-fmax-relevant-binds=⟨n⟩
    default: 6. Set the maximum number of bindings to display in type error messages.

-fmax-valid-hole-fits=⟨n⟩
    default: 6. Set the maximum number of valid hole fits for typed holes to display in type error messages.

-fno-show-valid-hole-fits
    Disables showing a list of valid hole fits for typed holes in type error messages.

-fno-sort-valid-hole-fits
    Disables the sorting of the list of valid hole fits for typed holes in type error messages.

-fprint-axiom-incomps
    Display equation incompatibilities in closed type families

-fprint-equality-relations
    Distinguish between equality relations when printing

-fprint-expanded-synonyms
    In type errors, also print type-synonym-expanded types.

-fprint-explicit-coercions
    Print coercions in types

-fprint-explicit-foralls
    Print explicit forall quantification in types. See also ExplicitForAll

-fprint-explicit-kinds
    Print explicit kind foralls and kind arguments in types. See also KindSignatures

-fprint-explicit-runtime-reps
    Print RuntimeRep variables in types which are runtime-representation polymorphic.

-fprint-potential-instances
    display all available instances in type error messages

-fprint-typechecker-elaboration
    Print extra information from typechecker.

-fprint-unicode-syntax
    Use unicode syntax when printing expressions, types and kinds. See also UnicodeSyntax

-frefinement-level-hole-fits=⟨n⟩
    default: off. Sets the level of refinement of the refinement hole fits, where level n means that hole fits of up to n holes will be considered.

-freverse-errors
    Output errors in reverse order

-fshow-docs-of-hole-fits
    Toggles whether to show the documentation of the valid hole fits in the output.

-fshow-hole-constraints
    Show constraints when reporting typed holes.

-fshow-hole-matches-of-hole-fits
    Toggles whether to show the type of the additional holes in refinement hole fits.

-fshow-provenance-of-hole-fits
    Toggles whether to show the provenance of the valid hole fits in the output.

-fshow-type-app-of-hole-fits
    Toggles whether to show the type application of the valid hole fits in the output.

-fshow-type-app-vars-of-hole-fits
    Toggles whether to show what type each quantified variable takes in a valid hole fit.

-fshow-type-of-hole-fits
    Toggles whether to show the type of the valid hole fits in the output.

-funclutter-valid-hole-fits
    Unclutter the list of valid hole fits by not showing provenance nor type applications of suggestions.

-Rghc-timing
    Summarise timing stats for GHC (same as +RTS -tstderr).

-v  verbose mode (equivalent to -v3)

-v⟨n⟩
    set verbosity level

  Warnings

-fdefer-out-of-scope-variables
    Convert variable out of scope variables errors into warnings. Implied by -fdefer-type-errors. See also -Wdeferred-out-of-scope-variables.

-fdefer-type-errors
    Turn type errors into warnings, deferring the error until runtime. Implies -fdefer-typed-holes and -fdefer-out-of-scope-variables. See also -Wdeferred-type-errors

-fdefer-typed-holes
    Convert typed hole errors into warnings, deferring the error until runtime. Implied by -fdefer-type-errors. See also -Wtyped-holes.

-fenable-th-splice-warnings
    Generate warnings for Template Haskell splices

-fhelpful-errors
    Make suggestions for mis-spelled names.

-fmax-pmcheck-models=⟨n⟩
    soft limit on the number of parallel models the pattern match checker should check a pattern match clause against

-fshow-warning-groups
    show which group an emitted warning belongs to.

-fvia-C
    use the C code generator

-W  enable normal warnings

-w  disable all warnings

-Wall
    enable almost all warnings (details in options-sanity)

-Wall-missed-specialisations
    warn when specialisation of any overloaded function fails.

-Wcompat
    enable future compatibility warnings (details in options-sanity)

-Wcompat-unqualified-imports
    Report unqualified imports of core libraries which are expected to cause compatibility problems in future releases.

-Wcpp-undef
    warn on uses of the #if directive on undefined identifiers

-Wdeferred-out-of-scope-variables
    Report warnings when variable out-of-scope errors are deferred until runtime. See -fdefer-out-of-scope-variables.

-Wdeferred-type-errors
    Report warnings when deferred type errors are enabled. This option is enabled by default. See -fdefer-type-errors.

-Wdeprecated-flags
    warn about uses of commandline flags that are deprecated

-Wdeprecations
    warn about uses of functions & types that have warnings or deprecated pragmas. Alias for -Wwarnings-deprecations

-Wderiving-defaults
    warn about default deriving when using both DeriveAnyClass and GeneralizedNewtypeDeriving

-Wdodgy-exports
    warn about dodgy exports

-Wdodgy-foreign-imports
    warn about dodgy foreign imports

-Wdodgy-imports
    warn about dodgy imports

-Wduplicate-constraints
    warn when a constraint appears duplicated in a type signature

-Wduplicate-exports
    warn when an entity is exported multiple times

-Wempty-enumerations
    warn about enumerations that are empty

-Werror
    make warnings fatal

-Weverything
    enable all warnings supported by GHC

-Whi-shadowing
    (deprecated) warn when a .hi file in the current directory shadows a library

-Widentities
    warn about uses of Prelude numeric conversions that are probably the identity (and hence could be omitted)

-Wimplicit-kind-vars
    warn when kind variables are implicitly quantified over.

-Wimplicit-prelude
    warn when the Prelude is implicitly imported

-Winaccessible-code
    warn about inaccessible code

-Wincomplete-patterns
    warn when a pattern match could fail

-Wincomplete-record-updates
    warn when a record update could fail

-Wincomplete-uni-patterns
    warn when a pattern match in a lambda expression or pattern binding could fail

-Winline-rule-shadowing
    Warn if a rewrite RULE might fail to fire because the function might be inlined before the rule has a chance to fire. See rules-inline.

-Wmissed-extra-shared-lib
    Warn when GHCi can't load a shared lib.

-Wmissed-specialisations
    warn when specialisation of an imported, overloaded function fails.

-Wmissing-deriving-strategies
    warn when a deriving clause is missing a deriving strategy

-Wmissing-export-lists
    warn when a module declaration does not explicitly list all exports

-Wmissing-exported-signatures
    warn about top-level functions without signatures, only if they are exported. takes precedence over -Wmissing-signatures

-Wmissing-exported-sigs
    (deprecated) warn about top-level functions without signatures, only if they are exported. takes precedence over -Wmissing-signatures

-Wmissing-fields
    warn when fields of a record are uninitialised

-Wmissing-home-modules
    warn when encountering a home module imported, but not listed on the command line. Useful for cabal to ensure GHC won't pick up modules, not listed neither in exposed-modules, nor in other-modules.

-Wmissing-import-lists
    warn when an import declaration does not explicitly list all the names brought into scope

-Wmissing-local-signatures
    warn about polymorphic local bindings without signatures

-Wmissing-local-sigs
    (deprecated) warn about polymorphic local bindings without signatures

-Wmissing-methods
    warn when class methods are undefined

-Wmissing-monadfail-instances
    Warn when a failable pattern is used in a do-block that does not have a MonadFail instance.

-Wmissing-pattern-synonym-signatures
    warn when pattern synonyms do not have type signatures

-Wmissing-signatures
    warn about top-level functions without signatures

-Wmonomorphism-restriction
    warn when the Monomorphism Restriction is applied

-Wname-shadowing
    warn when names are shadowed

-Wno-compat
    Disables all warnings enabled by -Wcompat.

-Wnoncanonical-monad-instances
    warn when Applicative or Monad instances have noncanonical definitions of return, pure, (>>), or (*>). See flag description in options-sanity for more details.

-Wnoncanonical-monadfail-instances
    warn when Monad or MonadFail instances have noncanonical definitions of fail. See flag description in options-sanity for more details.

-Wnoncanonical-monoid-instances
    warn when Semigroup or Monoid instances have noncanonical definitions of (<>) or mappend. See flag description in options-sanity for more details.

-Worphans
    warn when the module contains orphan instance declarations or rewrite rules

-Woverflowed-literals
    warn about literals that will overflow their type

-Woverlapping-patterns
    warn about overlapping patterns

-Wpartial-fields
    warn when defining a partial record field.

-Wpartial-type-signatures
    warn about holes in partial type signatures when PartialTypeSignatures is enabled. Not applicable when PartialTypeSignatures is not enabled, in which case errors are generated for such holes.

-Wredundant-constraints
    Have the compiler warn about redundant constraints in type signatures.

-Wredundant-record-wildcards
    Warn about record wildcard matches when the wildcard binds no patterns.

-Wsafe
    warn if the module being compiled is regarded to be safe.

-Wsemigroup
    warn when a Monoid is not Semigroup, and on non- Semigroup definitions of (<>)?

-Wsimplifiable-class-constraints
    Warn about class constraints in a type signature that can be simplified using a top-level instance declaration.

-Wspace-after-bang
    warn for missing space before the second argument of an infix definition of (!) when BangPatterns are not enabled

-Wstar-binder
    warn about binding the (*) type operator despite StarIsType

-Wstar-is-type
    warn when * is used to mean Data.Kind.Type

-Wtabs
    warn if there are tabs in the source file

-Wtrustworthy-safe
    warn if the module being compiled is marked as Trustworthy but it could instead be marked as Safe, a more informative bound.

-Wtype-defaults
    warn when defaulting happens

-Wtyped-holes
    Report warnings when typed hole errors are deferred until runtime. See -fdefer-typed-holes.

-Wunbanged-strict-patterns
    warn on pattern bind of unlifted variable that is neither bare nor banged

-Wunrecognised-pragmas
    warn about uses of pragmas that GHC doesn't recognise

-Wunrecognised-warning-flags
    throw a warning when an unrecognised -W... flag is encountered on the command line.

-Wunsafe
    warn if the module being compiled is regarded to be unsafe. See safe-haskell

-Wunsupported-calling-conventions
    warn about use of an unsupported calling convention

-Wunsupported-llvm-version
    Warn when using -fllvm with an unsupported version of LLVM.

-Wunticked-promoted-constructors
    warn if promoted constructors are not ticked

-Wunused-binds
    warn about bindings that are unused. Alias for -Wunused-top-binds, -Wunused-local-binds and -Wunused-pattern-binds

-Wunused-do-bind
    warn about do bindings that appear to throw away values of types other than ()

-Wunused-foralls
    warn about type variables in user-written forall\s that are unused

-Wunused-imports
    warn about unnecessary imports

-Wunused-local-binds
    warn about local bindings that are unused

-Wunused-matches
    warn about variables in patterns that aren't used

-Wunused-packages
    warn when package is requested on command line, but was never loaded.

-Wunused-pattern-binds
    warn about pattern match bindings that are unused

-Wunused-record-wildcards
    Warn about record wildcard matches when none of the bound variables are used.

-Wunused-top-binds
    warn about top-level bindings that are unused

-Wunused-type-patterns
    warn about unused type variables which arise from patterns in in type family and data family instances

-Wwarn
    make warnings non-fatal

-Wwarnings-deprecations
    warn about uses of functions & types that have warnings or deprecated pragmas

-Wwrong-do-bind
    warn about do bindings that appear to throw away monadic values that you should have bound instead

COPYRIGHT

Copyright 2015. The University Court of the University of Glasgow. All rights reserved.

AUTHOR
The GHC Team

COPYRIGHT
2015, GHC Team