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GHC(1)                     Glasgow Haskell Compiler                     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 DVI, PostScript and HTML; see below. 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 .x_o way x object files; common ways are: p, u, s .x_hi way x interface files

OPTIONS

Verbosity options -v -vn -fprint-explicit-foralls -fprint-explicit-kinds -ferror-spans -Hsize -Rghc-timing Alternative modes of operation --help,-? --interactive --make -e expr --show-iface -M --supported-extensions, --supported-languages --show-options --info --version, -V --numeric-version --print-libdir Which phases to run -E -C -S -c -x suffix Redirecting output -hcsuf suffix -hidir dir -hisuf suffix -o filename -odir dir -ohi filename -osuf suffix -stubdir dir -dumpdir dir -outputdir dir Keeping intermediate files -keep-hc-file or -keep-hc-files -keep-llvm-file or -keep-llvm-files -keep-s-file or -keep-s-files -keep-tmp-files Temporary files -tmpdir Finding imports -idir1:dir2:... -i Interface file options -ddump-hi -ddump-hi-diffs -ddump-minimal-imports --show-iface file Recompilation checking -fforce-recomp -fno-force-recomp Interactive-mode options -ignore-dot-ghci -ghci-script -fbreak-on-error -fno-break-on-error -fbreak-on-exception -fno-break-on-exception -fghci-hist-size=n (default is 50) -fprint-evld-with-show -fno-print-evld-with-show -fprint-bind-result -fno-print-bind-result -fno-print-bind-contents -fno-implicit-import-qualified -interactive-print Packages -this-package-key P -package P -hide-all-packages -hide-package name -ignore-package name -package-db file -clear-package-db -no-global-package-db -global-package-db -no-user-package-db -user-package-db -no-auto-link-packages -trust P -distrust P -distrust-all Language options -fcontext-stack=n -fglasgow-exts -fno-glasgow-exts -firrefutable-tuples -fno-irrefutable-tuples -fpackage-trust -ftype-function-depth=n -XAllowAmbiguousTypes -XNoAllowAmbiguousTypes -XArrows -XNoArrows -XAutoDeriveTypeable -XNoAutoDeriveTypeable -XBangPatterns -XNoBangPatterns -XBinaryLiterals -XNoBinaryLiterals -XCApiFFI -XNoCAPIFFI -XConstrainedClassMethods -XNoConstrainedClassMethods -XConstraintKinds -XNoConstraintKinds -XCPP -XNoCPP -XDataKinds -XNoDataKinds -XDefaultSignatures -XNoDefaultSignatures -XDeriveAnyClass -XNoDeriveAnyClass -XDeriveDataTypeable -XNoDeriveDataTypeable -XDeriveFunctor -XNoDeriveFunctor -XDeriveFoldable -XNoDeriveFoldable -XDeriveGeneric -XNoDeriveGeneric -XDeriveTraversable -XNoDeriveTraversable -XDisambiguateRecordFields -XNoDisambiguateRecordFields -XEmptyCase -XNoEmptyCase -XEmptyDataDecls -XNoEmptyDataDecls -XExistentialQuantification -XNoExistentialQuantification -XExplicitForAll -XNoExplicitForAll -XExplicitNamespaces -XNoExplicitNamespaces -XExtendedDefaultRules -XNoExtendedDefaultRules -XFlexibleContexts -XNoFlexibleContexts -XFlexibleInstances -XNoFlexibleInstances -XForeignFunctionInterface -XNoForeignFunctionInterface -XFunctionalDependencies -XNoFunctionalDependencies -XGADTs -XNoGADTs -XGADTSyntax -XNoGADTSyntax -XGeneralizedNewtypeDeriving -XNoGeneralizedNewtypeDeriving -XGenerics -XNoGenerics -XImplicitParams -XNoImplicitParams -XNoImplicitPrelude -XImplicitPrelude -XImpredicativeTypes -XNoImpredicativeTypes -XIncoherentInstances -XNoIncoherentInstances -XInstanceSigs -XNoInstanceSigs -XInterruptibleFFI -XNoInterruptibleFFI -XKindSignatures -XNoKindSignatures -XLambdaCase -XNoLambdaCase -XLiberalTypeSynonyms -XNoLiberalTypeSynonyms -XMagicHash -XNoMagicHash -XMonadComprehensions -XNoMonadComprehensions -XMonoLocalBinds -XNoMonoLocalBinds -XNoMonomorphismRestriction -XMonomorphismRestriction -XMultiParamTypeClasses -XNoMultiParamTypeClasses -XMultiWayIf -XNoMultiWayIf -XNamedFieldPuns -XNoNamedFieldPuns -XNamedWildCards -XNoNamedWildCards -XNegativeLiterals -XNoNegativeLiterals -XNoNPlusKPatterns -XNPlusKPatterns -XNullaryTypeClasses -XNoNullaryTypeClasses -XNumDecimals -XNoNumDecimals -XOverlappingInstances -XNoOverlappingInstances -XOverloadedLists -XNoOverloadedLists -XOverloadedStrings -XNoOverloadedStrings -XPackageImports -XNoPackageImports -XParallelArrays -XNoParallelArrays -XParallelListComp -XNoParallelListComp -XPartialTypeSignatures -XNoPartialTypeSignatures -XPatternGuards -XNoPatternGuards -XPatternSynonyms -XNoPatternSynonyms -XPolyKinds -XNoPolyKinds -XPolymorphicComponents -XNoPolymorphicComponents -XPostfixOperators -XNoPostfixOperators -XQuasiQuotes -XNoQuasiQuotes -XRank2Types -XNoRank2Types -XRankNTypes -XNoRankNTypes -XRebindableSyntax -XNoRebindableSyntax -XRecordWildCards -XNoRecordWildCards -XRecursiveDo -XNoRecursiveDo -XRelaxedPolyRec -XNoRelaxedPolyRec -XRoleAnnotations -XNoRoleAnnotations -XSafe -XScopedTypeVariables -XNoScopedTypeVariables -XStandaloneDeriving -XNoStandaloneDeriving -XTemplateHaskell -XNoTemplateHaskell -XNoTraditionalRecordSyntax -XTraditionalRecordSyntax -XTransformListComp -XNoTransformListComp -XTrustworthy -XTupleSections -XNoTupleSections -XTypeFamilies -XNoTypeFamilies -XTypeOperators -XNoTypeOperators -XTypeSynonymInstances -XNoTypeSynonymInstances -XUnboxedTuples -XNoUnboxedTuples -XUndecidableInstances -XNoUndecidableInstances -XUnicodeSyntax -XNoUnicodeSyntax -XUnliftedFFITypes -XNoUnliftedFFITypes -XUnsafe -XViewPatterns -XNoViewPatterns Warnings -W -w -w -Wall -w -Werror -Wwarn -fdefer-type-errors -fno-defer-type-errors -fdefer-typed-holes -fno-defer-typed-holes -fhelpful-errors -fno-helpful-errors -fwarn-deprecated-flags -fno-warn-deprecated-flags -fwarn-duplicate-constraints -fno-warn-duplicate-constraints -fwarn-duplicate-exports -fno-warn-duplicate-exports -fwarn-hi-shadowing -fno-warn-hi-shadowing -fwarn-identities -fno-warn-identities -fwarn-implicit-prelude -fno-warn-implicit-prelude -fwarn-incomplete-patterns -fno-warn-incomplete-patterns -fwarn-incomplete-uni-patterns -fno-warn-incomplete-uni-patterns -fwarn-incomplete-record-updates -fno-warn-incomplete-record-updates -fwarn-lazy-unlifted-bindings -fno-warn-lazy-unlifted-bindings -fwarn-missing-fields -fno-warn-missing-fields -fwarn-missing-import-lists -fnowarn-missing-import-lists -fwarn-missing-methods -fno-warn-missing-methods -fwarn-missing-signatures -fno-warn-missing-signatures -fwarn-missing-exported-sigs -fno-warn-missing-exported-sigs -fwarn-missing-local-sigs -fno-warn-missing-local-sigs -fwarn-monomorphism-restriction -fno-warn-monomorphism-restriction -fwarn-name-shadowing -fno-warn-name-shadowing -fwarn-orphans, -fwarn-auto-orphans -fno-warn-orphans, -fno-warn-auto-orphans -fwarn-overlapping-patterns -fno-warn-overlapping-patterns -fwarn-tabs -fno-warn-tabs -fwarn-type-defaults -fno-warn-type-defaults -fwarn-unrecognised-pragmas -fno-warn-unrecognised-pragmas -fwarn-unticked-promoted-constructors -fno-warn-unticked-promoted-constructors -fwarn-unused-binds -fno-warn-unused-binds -fwarn-unused-imports -fno-warn-unused-imports -fwarn-unused-matches -fno-warn-unused-matches -fwarn-unused-do-bind -fno-warn-unused-do-bind -fwarn-wrong-do-bind -fno-warn-wrong-do-bind -fwarn-unsafe -fno-warn-unsafe -fwarn-safe -fno-warn-safe -fwarn-trustworthy-safe -fno-warn-safe -fwarn-warnings-deprecations -fno-warn-warnings-deprecations -fwarn-amp -fno-warn-amp -fwarn-typed-holes -fno-warn-typed-holes -fwarn-partial-type-signatures -fno-warn-partial-type-signatures -fwarn-deriving-typeable -fno-warn-deriving-typeable Optimisation levels -O0 -O -O or -O1 -O0 -O2 -O0 -Odph Individual optimisations -fcall-arity -fno-call-arity -fcase-merge -fno-case-merge -fcmm-elim-common-blocks -fno-cmm-elim-common-blocks -fcmm-sink -fno-cmm-sink -fcpr-off -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 -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 -fliberate-case -fliberate-case-threshold=n -fno-liberate-case-threshold -floopification -fno-loopification -fmax-inline-alloc-size=n -fmax-inline-memcpy-insns=n -fmax-inline-memset-insns=n -fmax-relevant-binds=n -fno-max-relevant-bindings -fmax-simplifier-iterations=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 -fpedantic-bottoms -fno-pedantic-bottoms -fregs-graph -fno-regs-graph -fregs-iterative -fno-regs-iterative -fsimplifier-phases=n -fsimpl-tick-factor=n -fspec-constr -fno-spec-constr -fspec-constr-count=n -fno-spec-constr-count -fspec-constr-threshold=n -fno-spec-constr-threshold -fspecialise -fno-specialise -fstatic-argument-transformation -fno-static-argument-transformation -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 -fvectorisation-avoidance -fno-vectorisation-avoidance -fvectorise -fno-vectorise Profiling options -prof -fprof-auto -fno-prof-auto -fprof-auto-top -fno-prof-auto -fprof-auto-exported -fno-prof-auto -fprof-cafs -fno-prof-cafs -fno-prof-count-entries -fprof-count-entries -ticky Program coverage options -fhpc -hpcdir dir Haskell pre-processor options -F C pre-processor options -cpp -Dsymbol=value -U -Usymbol -Idir Code generation options -fasm -fllvm -fno-code -fwrite-interface -fbyte-code -fobject-code Linking options -shared -staticlib -fPIC -dynamic -dynamic-too -dyno -dynosuf -dynload -framework name -framework-path name -llib -Ldir -main-is --mk-dll -no-hs-main -rtsopts, -rtsopts={none,some,all} -with-rtsopts=opts -no-link -split-objs -static -threaded -debug -ticky -eventlog -fno-gen-manifest -fno-embed-manifest -fno-shared-implib -dylib-install-name path -rdynamic Plugin options -fplugin=module -fplugin-opt=module:args Replacing phases -pgmL cmd -pgmP cmd -pgmc cmd -pgmlo cmd -pgmlc cmd -pgms cmd -pgma cmd -pgml cmd -pgmdll cmd -pgmF cmd -pgmwindres cmd -pgmlibtool cmd Forcing options to particular phases -optL option -optP option -optF option -optc option -optlo option -optlc option -opta option -optl option -optdll option -optwindres option Platform-specific options -msse2 Compiler debugging options -dcore-lint -ddump-to-file -ddump-asm -ddump-bcos -ddump-cmm -ddump-core-stats -ddump-cse -ddump-deriv -ddump-ds -ddump-foreign -ddump-hpc -ddump-inlinings -ddump-llvm -ddump-occur-anal -ddump-opt-cmm -ddump-parsed -ddump-prep -ddump-rn -ddump-rule-firings -ddump-rule-rewrites -ddump-rules -ddump-vect -ddump-simpl -ddump-simpl-iterations -ddump-spec -ddump-splices -ddump-stg -ddump-stranal -ddump-strsigs -ddump-tc -dth-dec-file -ddump-types -ddump-worker-wrapper -ddump-if-trace -ddump-tc-trace -ddump-vt-trace -ddump-rn-trace -ddump-rn-stats -ddump-simpl-stats -dno-debug-output -dppr-debug -dppr-user-length -dppr-colsNNN -dppr-case-as-let -dsuppress-all -dsuppress-uniques -dsuppress-idinfo -dsuppress-module-prefixes -dsuppress-type-signatures -dsuppress-type-applications -dsuppress-coercions -dsource-stats -dcmm-lint -dstg-lint -dstg-stats -dverbose-core2core -dverbose-stg2stg -dshow-passes -dfaststring-stats -frule-check Misc compiler options -jN -fno-hi-version-check -fhistory-size -fno-ghci-history -fno-ghci-sandbox

VERBOSITY OPTIONS

-v verbose mode (equivalent to -v3) [dynamic] -vn set verbosity level [dynamic] -fprint-explicit-foralls print explicit forall quantification in types [dynamic] -fprint-explicit-kinds print explicit kind foralls and kind arguments in types [dynamic] -ferror-spans output full span in error messages [dynamic] -Hsize Set the minimum heap size to size [dynamic] -Rghc-timing Summarise timing stats for GHC (same as +RTS -tstderr) [dynamic]

ALTERNATIVE MODES OF OPERATION

--help,-? Disply help [mode] --interactive Interactive mode - normally used by just running ghci; see for details. [mode] --make Build a multi-module Haskell program, automatically figuring out dependencies. Likely to be much easier, and faster, than using make; see for details.. [mode] -e expr Evaluate expr; see for details. [mode] --show-iface Display the contents of an interface file. [mode] -M Generate dependency information suitable for use in a Makefile; see for details. [mode] --supported-extensions, --supported-languages display the supported language extensions [mode] --show-options display the supported command line options [mode] --info display information about the compiler [mode] --version, -V display GHC version [mode] --numeric-version display GHC version (numeric only) [mode] --print-libdir display GHC library directory [mode]

WHICH PHASES TO RUN

-E Stop after preprocessing (.hspp file) [mode] -C Stop after generating C (.hc file) [mode] -S Stop after generating assembly (.s file) [mode] -c Stop after generating object (.o) file [mode] -x suffix Override default behaviour for source files [dynamic]

REDIRECTING OUTPUT

-hcsuf suffix set the suffix to use for intermediate C files [dynamic] -hidir dir set directory for interface files [dynamic] -hisuf suffix set the suffix to use for interface files [dynamic] -o filename set output filename [dynamic] -odir dir set directory for object files [dynamic] -ohi filename set the filename in which to put the interface [dynamic] -osuf suffix set the output file suffix [dynamic] -stubdir dir redirect FFI stub files [dynamic] -dumpdir dir redirect dump files [dynamic] -outputdir dir set output directory [dynamic]

KEEPING INTERMEDIATE FILES

-keep-hc-file or -keep-hc-files retain intermediate .hc files [dynamic] -keep-llvm-file or -keep-llvm-files retain intermediate LLVM .ll files [dynamic] -keep-s-file or -keep-s-files retain intermediate .s files [dynamic] -keep-tmp-files retain all intermediate temporary files [dynamic]

TEMPORARY FILES

-tmpdir set the directory for temporary files [dynamic]

FINDING IMPORTS

-idir1:dir2:... add dir, dir2, etc. to import path [dynamic/:set] -i Empty the import directory list [dynamic/:set]

INTERFACE FILE OPTIONS

-ddump-hi Dump the new interface to stdout [dynamic] -ddump-hi-diffs Show the differences vs. the old interface [dynamic] -ddump-minimal-imports Dump a minimal set of imports [dynamic] --show-iface file See . []

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). [dynamic] INTERACTIVE-MODE OPTIONS -ignore-dot-ghci Disable reading of .ghci files [dynamic] -ghci-script Read additional .ghci files [dynamic] -fbreak-on-error Break on uncaught exceptions and errors [dynamic] -fbreak-on-exception Break on any exception thrown [dynamic] -fghci-hist-size=n Set the number of entries GHCi keeps for :history [dynamic] -fprint-evld-with-show Enable usage of Show instances in :print [dynamic] -fprint-bind-result Turn on printing of binding results in GHCi [dynamic] -fno-print-bind-contents Turn off printing of binding contents in GHCi [dynamic] -fno-implicit-import-qualified Turn off implicit qualified import of everything in GHCi [dynamic] -interactive-print Select the function to use for printing evaluated expressions in GHCi [dynamic]

PACKAGES

-this-package-key P Compile to be part of package P [dynamic] -package P Expose package P [dynamic/:set] -hide-all-packages Hide all packages by default [dynamic] -hide-package name Hide package P [dynamic/:set] -ignore-package name Ignore package P [dynamic/:set] -package-db file Add file to the package db stack. [dynamic] -clear-package-db Clear the package db stack. [dynamic] -no-global-package-db Remove the global package db from the stack. [dynamic] -global-package-db Add the global package db to the stack. [dynamic] -no-user-package-db Remove the user's package db from the stack. [dynamic] -user-package-db Add the user's package db to the stack. [dynamic] -no-auto-link-packages Don't automatically link in the base and rts packages. [dynamic] -trust P Expose package P and set it to be trusted [dynamic/:set] -distrust P Expose package P and set it to be distrusted [dynamic/:set] -distrust-all Distrust all packages by default [dynamic/:set]

LANGUAGE OPTIONS

-fcontext-stack=n set the limit for type-class context reduction. Default is 100. [dynamic] -fglasgow-exts Deprecated. Enable most language extensions; see for exactly which ones. [dynamic] -firrefutable-tuples Make tuple pattern matching irrefutable [dynamic] -fpackage-trust Enable Safe Haskell trusted package requirement for trustworthy modules. [dynamic] -ftype-function-depth=n set the limit for type function reductions. Default is 200. [dynamic] -XAllowAmbiguousTypes Allow the user to write ambiguous types, and the type inference engine to infer them. [dynamic] -XArrows Enable arrow notation extension [dynamic] -XAutoDeriveTypeable As of GHC 7.10, this option is not needed, and should not be used. Automatically derive Typeable instances for every datatype and type class declaration. Implies -XDeriveDataTypeable. [dynamic] -XBangPatterns Enable bang patterns. [dynamic] -XBinaryLiterals Enable support for binary literals. [dynamic] -XCApiFFI Enable the CAPI calling convention. [dynamic] -XConstrainedClassMethods Enable constrained class methods. [dynamic] -XConstraintKinds Enable a kind of constraints. [dynamic] -XCPP Enable the C preprocessor. [dynamic] -XDataKinds Enable datatype promotion. [dynamic] -XDefaultSignatures Enable default signatures. [dynamic] -XDeriveAnyClass Enable deriving for any class. [dynamic] -XDeriveDataTypeable Enable deriving for the Data class. Implied by -XAutoDeriveTypeable. [dynamic] -XDeriveFunctor Enable deriving for the Functor class. Implied by -XDeriveTraversable. [dynamic] -XDeriveFoldable Enable deriving for the Foldable class. Implied by -XDeriveTraversable. [dynamic] -XDeriveGeneric Enable deriving for the Generic class. [dynamic] -XDeriveTraversable Enable deriving for the Traversable class. Implies -XDeriveFunctor and -XDeriveFoldable. [dynamic] -XDisambiguateRecordFields Enable record field disambiguation. Implied by -XRecordWildCards. [dynamic] -XEmptyCase Allow empty case alternatives. [dynamic] -XEmptyDataDecls Enable empty data declarations. [dynamic] -XExistentialQuantification Enable existential quantification. [dynamic] -XExplicitForAll Enable explicit universal quantification. Implied by -XScopedTypeVariables, -XLiberalTypeSynonyms, -XRankNTypes and -XExistentialQuantification. [dynamic] -XExplicitNamespaces Enable using the keyword type to specify the namespace of entries in imports and exports (). Implied by -XTypeOperators and -XTypeFamilies. [dynamic] -XExtendedDefaultRules Use GHCi's extended default rules in a normal module. [dynamic] -XFlexibleContexts Enable flexible contexts. Implied by -XImplicitParams. [dynamic] -XFlexibleInstances Enable flexible instances. Implies -XTypeSynonymInstances. Implied by -XImplicitParams. [dynamic] -XForeignFunctionInterface Enable foreign function interface. [dynamic] -XFunctionalDependencies Enable functional dependencies. Implies -XMultiParamTypeClasses. [dynamic] -XGADTs Enable generalised algebraic data types. Implies -XGADTSyntax and -XMonoLocalBinds. [dynamic] -XGADTSyntax Enable generalised algebraic data type syntax. [dynamic] -XGeneralizedNewtypeDeriving Enable newtype deriving. [dynamic] -XGenerics Deprecated, does nothing. No longer enables generic classes. See also GHC's support for generic programming. [dynamic] -XImplicitParams Enable Implicit Parameters. Implies -XFlexibleContexts and -XFlexibleInstances. [dynamic] -XNoImplicitPrelude Don't implicitly import Prelude. Implied by -XRebindableSyntax. [dynamic] -XImpredicativeTypes Enable impredicative types. Implies -XRankNTypes. [dynamic] -XIncoherentInstances Enable incoherent instances. Implies -XOverlappingInstances. [dynamic] -XInstanceSigs Enable instance signatures. [dynamic] -XInterruptibleFFI Enable interruptible FFI. [dynamic] -XKindSignatures Enable kind signatures. Implied by -XTypeFamilies and -XPolyKinds. [dynamic] -XLambdaCase Enable lambda-case expressions. [dynamic] -XLiberalTypeSynonyms Enable liberalised type synonyms. [dynamic] -XMagicHash Allow "#" as a postfix modifier on identifiers. [dynamic] -XMonadComprehensions Enable monad comprehensions. [dynamic] -XMonoLocalBinds Enable do not generalise local bindings. Implied by -XTypeFamilies and -XGADTs. [dynamic] -XNoMonomorphismRestriction Disable the monomorphism restriction. [dynamic] -XMultiParamTypeClasses Enable multi parameter type classes. Implied by -XFunctionalDependencies. [dynamic] -XMultiWayIf Enable multi-way if-expressions. [dynamic] -XNamedFieldPuns Enable record puns. [dynamic] -XNamedWildCards Enable named wildcards. [dynamic] -XNegativeLiterals Enable support for negative literals. [dynamic] -XNoNPlusKPatterns Disable support for n+k patterns. [dynamic] -XNullaryTypeClasses Deprecated, does nothing. nullary (no parameter) type classes are now enabled using -XMultiParamTypeClasses. [dynamic] -XNumDecimals Enable support for 'fractional' integer literals. [dynamic] -XOverlappingInstances Enable overlapping instances. [dynamic] -XOverloadedLists Enable overloaded lists. [dynamic] -XOverloadedStrings Enable overloaded string literals. [dynamic] -XPackageImports Enable package-qualified imports. [dynamic] -XParallelArrays Enable parallel arrays. Implies -XParallelListComp. [dynamic] -XParallelListComp Enable parallel list comprehensions. Implied by -XParallelArrays. [dynamic] -XPartialTypeSignatures Enable partial type signatures. [dynamic] -XPatternGuards Enable pattern guards. [dynamic] -XPatternSynonyms Enable pattern synonyms. [dynamic] -XPolyKinds Enable kind polymorphism. Implies -XKindSignatures. [dynamic] -XPolymorphicComponents Enable polymorphic components for data constructors. [dynamic, synonym for -XRankNTypes] -XPostfixOperators Enable postfix operators. [dynamic] -XQuasiQuotes Enable quasiquotation. [dynamic] -XRank2Types Enable rank-2 types. [dynamic, synonym for -XRankNTypes] -XRankNTypes Enable rank-N types. Implied by -XImpredicativeTypes. [dynamic] -XRebindableSyntax Employ rebindable syntax. Implies -XNoImplicitPrelude. [dynamic] -XRecordWildCards Enable record wildcards. Implies -XDisambiguateRecordFields. [dynamic] -XRecursiveDo Enable recursive do (mdo) notation. [dynamic] -XRelaxedPolyRec (deprecated) Relaxed checking for mutually-recursive polymorphic functions. [dynamic] -XRoleAnnotations Enable role annotations. [dynamic] -XSafe Enable the Safe Haskell Safe mode. [dynamic] -XScopedTypeVariables Enable lexically-scoped type variables. [dynamic] -XStandaloneDeriving Enable standalone deriving. [dynamic] -XTemplateHaskell Enable Template Haskell. [dynamic] -XNoTraditionalRecordSyntax Disable support for traditional record syntax (as supported by Haskell 98) C {f = x} [dynamic] -XTransformListComp Enable generalised list comprehensions. [dynamic] -XTrustworthy Enable the Safe Haskell Trustworthy mode. [dynamic] -XTupleSections Enable tuple sections. [dynamic] -XTypeFamilies Enable type families. Implies -XExplicitNamespaces, -XKindSignatures and -XMonoLocalBinds. [dynamic] -XTypeOperators Enable type operators. Implies -XExplicitNamespaces. [dynamic] -XTypeSynonymInstances Enable type synonyms in instance heads. Implied by -XFlexibleInstances. [dynamic] -XUnboxedTuples Enable unboxed tuples. [dynamic] -XUndecidableInstances Enable undecidable instances. [dynamic] -XUnicodeSyntax Enable unicode syntax. [dynamic] -XUnliftedFFITypes Enable unlifted FFI types. [dynamic] -XUnsafe Enable Safe Haskell Unsafe mode. [dynamic] -XViewPatterns Enable view patterns. [dynamic]

WARNINGS

-W enable normal warnings [dynamic] -w disable all warnings [dynamic] -Wall enable almost all warnings (details in ) [dynamic] -Werror make warnings fatal [dynamic] -Wwarn make warnings non-fatal [dynamic] -fdefer-type-errors Turn type errors into warnings, deferring the error until runtime. Implies -fdefer-typed-holes. [dynamic] -fdefer-typed-holes Convert typed hole errors into warnings, deferring the error until runtime. Implied by -fdefer-type-errors. See also -fwarn-typed-holes. [dynamic] -fhelpful-errors Make suggestions for mis-spelled names. [dynamic] -fwarn-deprecated-flags warn about uses of commandline flags that are deprecated [dynamic] -fwarn-duplicate-constraints warn when a constraint appears duplicated in a type signature [dynamic] -fwarn-duplicate-exports warn when an entity is exported multiple times [dynamic] -fwarn-hi-shadowing warn when a .hi file in the current directory shadows a library [dynamic] -fwarn-identities warn about uses of Prelude numeric conversions that are probably the identity (and hence could be omitted) [dynamic] -fwarn-implicit-prelude warn when the Prelude is implicitly imported [dynamic] -fwarn-incomplete-patterns warn when a pattern match could fail [dynamic] -fwarn-incomplete-uni-patterns warn when a pattern match in a lambda expression or pattern binding could fail [dynamic] -fwarn-incomplete-record-updates warn when a record update could fail [dynamic] -fwarn-lazy-unlifted-bindings (deprecated) warn when a pattern binding looks lazy but must be strict [dynamic] -fwarn-missing-fields warn when fields of a record are uninitialised [dynamic] -fwarn-missing-import-lists warn when an import declaration does not explicitly list all the names brought into scope [dynamic] -fwarn-missing-methods warn when class methods are undefined [dynamic] -fwarn-missing-signatures warn about top-level functions without signatures [dynamic] -fwarn-missing-exported-sigs warn about top-level functions without signatures, only if they are exported. takes precedence over -fwarn-missing-signatures [dynamic] -fwarn-missing-local-sigs warn about polymorphic local bindings without signatures [dynamic] -fwarn-monomorphism-restriction warn when the Monomorphism Restriction is applied [dynamic] -fwarn-name-shadowing warn when names are shadowed [dynamic] -fwarn-orphans, -fwarn-auto-orphans warn when the module contains orphan instance declarations or rewrite rules [dynamic] -fwarn-overlapping-patterns warn about overlapping patterns [dynamic] -fwarn-tabs warn if there are tabs in the source file [dynamic] -fwarn-type-defaults warn when defaulting happens [dynamic] -fwarn-unrecognised-pragmas warn about uses of pragmas that GHC doesn't recognise [dynamic] -fwarn-unticked-promoted-constructors warn if promoted constructors are not ticked [dynamic] -fwarn-unused-binds warn about bindings that are unused [dynamic] -fwarn-unused-imports warn about unnecessary imports [dynamic] -fwarn-unused-matches warn about variables in patterns that aren't used [dynamic] -fwarn-unused-do-bind warn about do bindings that appear to throw away values of types other than () [dynamic] -fwarn-wrong-do-bind warn about do bindings that appear to throw away monadic values that you should have bound instead [dynamic] -fwarn-unsafe warn if the module being compiled is regarded to be unsafe. Should be used to check the safety status of modules when using safe inference. Works on all module types, even those using explicit Safe Haskell modes (such as -XTrustworthy) and so can be used to have the compiler check any assumptions made. [dynamic] -fwarn-safe warn if the module being compiled is regarded to be safe. Should be used to check the safety status of modules when using safe inference. Works on all module types, even those using explicit Safe Haskell modes (such as -XTrustworthy) and so can be used to have the compiler check any assumptions made. [dynamic] -fwarn-trustworthy-safe warn if the module being compiled is marked as -XTrustworthy but it could instead be marked as -XSafe, a more informative bound. Can be used to detect once a Safe Haskell bound can be improved as dependencies are updated. [dynamic] -fwarn-warnings-deprecations warn about uses of functions & types that have warnings or deprecated pragmas [dynamic] -fwarn-amp (deprecated) warn on definitions conflicting with the Applicative-Monad Proposal (AMP) [dynamic] -fwarn-typed-holes Report warnings when typed hole errors are deferred until runtime. See -fdefer-typed-holes. [dynamic] -fwarn-partial-type-signatures warn about holes in partial type signatures when -XPartialTypesignatures is enabled. Not applicable when -XPartialTypesignatures is not enabled, in which case errors are generated for such holes. See . [dynamic] -fwarn-deriving-typeable warn when encountering a request to derive an instance of class Typeable. As of GHC 7.10, such declarations are unnecessary and are ignored by the compiler because GHC has a custom solver for discharging this type of constraint. [dynamic]

OPTIMISATION LEVELS

-O0 Disable optimisations (default) [dynamic] -O or -O1 Enable level 1 optimisations [dynamic] -O2 Enable level 2 optimisations [dynamic] -Odph Enable level 2 optimisations, set -fmax-simplifier-iterations=20 and -fsimplifier-phases=3. [dynamic]

INDIVIDUAL OPTIMISATIONS

-fcall-arity Enable call-arity optimisation. Implied by -O. [dynamic] -fcase-merge Enable case-merging. Implied by -O. [dynamic] -fcmm-elim-common-blocks Enable Cmm common block elimination. Implied by -O. [dynamic] -fcmm-sink Enable Cmm sinking. Implied by -O. [dynamic] -fcpr-off Switch off CPR analysis in the demand analyser. [static] -fcse Enable common sub-expression elimination. Implied by -O. [dynamic] -fdicts-cheap Make dictionary-valued expressions seem cheap to the optimiser. [dynamic] -fdicts-strict Make dictionaries strict [dynamic] -fdmd-tx-dict-sel Use a special demand transformer for dictionary selectors. Always enabled by default. [dynamic] -fdo-eta-reduction Enable eta-reduction. Implied by -O. [dynamic] -fdo-lambda-eta-expansion Enable lambda eta-expansion. Always enabled by default. [dynamic] -feager-blackholing Turn on eager blackholing [dynamic] -fenable-rewrite-rules Switch on all rewrite rules (including rules generated by automatic specialisation of overloaded functions). Implied by -O. [dynamic] -fexcess-precision Enable excess intermediate precision [dynamic] -fexpose-all-unfoldings Expose all unfoldings, even for very large or recursive functions. [dynamic] -ffloat-in Turn on the float-in transformation. Implied by -O. [dynamic] -ffull-laziness Turn on full laziness (floating bindings outwards). Implied by -O. [dynamic] -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. [dynamic] -fignore-asserts Ignore assertions in the source. Implied by -O. [dynamic] -fignore-interface-pragmas Ignore pragmas in interface files. Implied by -O0 only. [dynamic] -flate-dmd-anal Run demand analysis again, at the end of the simplification pipeline [dynamic] -fliberate-case Turn on the liberate-case transformation. Implied by -O2. [dynamic] -fliberate-case-threshold=n Set the size threshold for the liberate-case transformation to n (default: 2000) [dynamis] -floopification Turn saturated self-recursive tail-calls into local jumps in the generated assembly. Implied by -O. [dynamic] -fmax-inline-alloc-size=n Set the maximum size of inline array allocations to n bytes (default: 128). GHC will allocate non-pinned arrays of statically known size in the current nursery block if they're no bigger than n bytes, ignoring GC overheap. This value should be quite a bit smaller than the block size (typically: 4096). [dynamic] -fmax-inline-memcpy-insns=n Inline memcpy calls if they would generate no more than n pseudo instructions (default: 32). [dynamic] -fmax-inline-memset-insns=n Inline memset calls if they would generate no more than n pseudo instructions (default: 32). [dynamic] -fmax-relevant-binds=n Set the maximum number of bindings to display in type error messages (default 6). [dynamic] -fmax-simplifier-iterations=n Set the max iterations for the simplifier (default 4). [dynamic] -fmax-worker-args=n If a worker has that many arguments, none will be unpacked anymore (default: 10) [dynamic] -fno-opt-coercion Turn off the coercion optimiser [static] -fno-pre-inlining Turn off pre-inlining [dynamic] -fno-state-hack Turn off the "state hack" whereby any lambda with a real-world state token as argument is considered to be single-entry. Hence OK to inline things inside it. [static] -fomit-interface-pragmas Don't generate interface pragmas. Implied by -O0 only. [dynamic] -fomit-yields Omit heap checks when no allocation is being performed. [dynamic] -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. [dynamic] -fregs-graph Use the graph colouring register allocator for register allocation in the native code generator. Implied by -O2. [dynamic] -fregs-iterative Use the iterative coalescing graph colouring register allocator in the native code generator. [dynamic] -fsimplifier-phases=n Set the number of phases for the simplifier (default 2). Ignored with -O0. [dynamic] -fsimpl-tick-factor=n Set the percentage factor for simplifier ticks (default 100) [dynamic] -fspec-constr Turn on the SpecConstr transformation. Implied by -O2. [dynamic] -fspec-constr-count=n Set to n (default: 3) the maximum number of specialisations that will be created for any one function by the SpecConstr transformation [dynamic] -fspec-constr-threshold=n Set the size threshold for the SpecConstr transformation to n (default: 2000) [dynamic] -fspecialise Turn on specialisation of overloaded functions. Implied by -O. [dynamic] -fstatic-argument-transformation Turn on the static argument transformation. [dynamic] -fstrictness Turn on strictness analysis. Implied by -O. [dynamic] -fstrictness-before=n Run an additional strictness analysis before simplifier phase n [dynamic] -funbox-small-strict-fields Flatten strict constructor fields with a pointer-sized representation. Implied by -O. [dynamic] -funbox-strict-fields Flatten strict constructor fields [dynamic] -funfolding-creation-threshold=n Tweak unfolding settings. Default: 750 [dynamic] -funfolding-dict-discount=n Tweak unfolding settings. Default: 30 [dynamic] -funfolding-fun-discount=n Tweak unfolding settings. Default: 60 [dynamic] -funfolding-keeness-factor=n Tweak unfolding settings. Default: 1.5 [dynamic] -funfolding-use-threshold=n Tweak unfolding settings. Default: 60 [dynamic] -fvectorisation-avoidance Enable vectorisation avoidance. Always enabled by default. [dynamic] -fvectorise Enable vectorisation of nested data parallelism [dynamic]

PROFILING OPTIONS

-prof Turn on profiling [dynamic] -fprof-auto Auto-add SCCs to all bindings not marked INLINE [dynamic] -fprof-auto-top Auto-add SCCs to all top-level bindings not marked INLINE [dynamic] -fprof-auto-exported Auto-add SCCs to all exported bindings not marked INLINE [dynamic] -fprof-cafs Auto-add SCCs to all CAFs [dynamic] -fno-prof-count-entries Do not collect entry counts [dynamic] -ticky Turn on ticky-ticky profiling [dynamic]

PROGRAM COVERAGE OPTIONS

-fhpc Turn on Haskell program coverage instrumentation [dynamic] -hpcdir dir Directory to deposit .mix files during compilation (default is .hpc) [dynamic] HASKELL PRE-PROCESSOR OPTIONS -F Enable the use of a pre-processor (set with -pgmF) [dynamic] C PRE-PROCESSOR OPTIONS -cpp Run the C pre-processor on Haskell source files [dynamic] -Dsymbol=value Define a symbol in the C pre-processor [dynamic] -Usymbol Undefine a symbol in the C pre-processor [dynamic] -Idir Add dir to the directory search list for #include files [dynamic]

CODE GENERATION OPTIONS

-fasm Use the native code generator [dynamic] -fllvm Compile using the LLVM code generator [dynamic] -fno-code Omit code generation [dynamic] -fwrite-interface Always write interface files [dynamic] -fbyte-code Generate byte-code [dynamic] -fobject-code Generate object code [dynamic]

LINKING OPTIONS

-shared Generate a shared library (as opposed to an executable) [dynamic] -staticlib On Darwin/OS X/iOS only, generate a standalone static library (as opposed to an executable). This is the usual way to compile for iOS. [dynamic] -fPIC Generate position-independent code (where available) [dynamic] -dynamic Use dynamic Haskell libraries (if available) [dynamic] -dynamic-too Build dynamic object files as well as static object files during compilation [dynamic] -dyno Set the output path for the dynamically linked objects [dynamic] -dynosuf Set the output suffix for dynamic object files [dynamic] -dynload Selects one of a number of modes for finding shared libraries at runtime. [dynamic] -framework name On Darwin/OS X/iOS only, link in the framework name. This option corresponds to the -framework option for Apple's Linker. [dynamic] -framework-path name 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. [dynamic] -llib Link in library lib [dynamic] -Ldir Add dir to the list of directories searched for libraries [dynamic] -main-is Set main module and function [dynamic] --mk-dll DLL-creation mode (Windows only) [dynamic] -no-hs-main Don't assume this program contains main [dynamic] -rtsopts, -rtsopts={none,some,all} 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), and all (or no argument at all) means that all RTS flags are permitted. [dynamic] -with-rtsopts=opts Set the default RTS options to opts. [dynamic] -no-link Omit linking [dynamic] -split-objs Split objects (for libraries) [dynamic] -static Use static Haskell libraries [dynamic] -threaded Use the threaded runtime [dynamic] -debug Use the debugging runtime [dynamic] -ticky For linking, this simply implies -debug; see . [dynamic] -eventlog Enable runtime event tracing [dynamic] -fno-gen-manifest Do not generate a manifest file (Windows only) [dynamic] -fno-embed-manifest Do not embed the manifest in the executable (Windows only) [dynamic] -fno-shared-implib Don't generate an import library for a DLL (Windows only) [dynamic] -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] -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. [dynamic]

PLUGIN OPTIONS

-fplugin=module Load a plugin exported by a given module [dynamic] -fplugin-opt=module:args Give arguments to a plugin module; module must be specified with -fplugin [dynamic]

REPLACING PHASES

-pgmL cmd Use cmd as the literate pre-processor [dynamic] -pgmP cmd Use cmd as the C pre-processor (with -cpp only) [dynamic] -pgmc cmd Use cmd as the C compiler [dynamic] -pgmlo cmd Use cmd as the LLVM optimiser [dynamic] -pgmlc cmd Use cmd as the LLVM compiler [dynamic] -pgms cmd Use cmd as the splitter [dynamic] -pgma cmd Use cmd as the assembler [dynamic] -pgml cmd Use cmd as the linker [dynamic] -pgmdll cmd Use cmd as the DLL generator [dynamic] -pgmF cmd Use cmd as the pre-processor (with -F only) [dynamic] -pgmwindres cmd Use cmd as the program for embedding manifests on Windows. [dynamic] -pgmlibtool cmd Use cmd as the command for libtool (with -staticlib only). [dynamic]

FORCING OPTIONS TO PARTICULAR PHASES

-optL option pass option to the literate pre-processor [dynamic] -optP option pass option to cpp (with -cpp only) [dynamic] -optF option pass option to the custom pre-processor [dynamic] -optc option pass option to the C compiler [dynamic] -optlo option pass option to the LLVM optimiser [dynamic] -optlc option pass option to the LLVM compiler [dynamic] -opta option pass option to the assembler [dynamic] -optl option pass option to the linker [dynamic] -optdll option pass option to the DLL generator [dynamic] -optwindres option pass option to windres. [dynamic] PLATFORM-SPECIFIC OPTIONS -msse2 (x86 only) Use SSE2 for floating point [dynamic]

COMPILER DEBUGGING OPTIONS

-dcore-lint Turn on internal sanity checking [dynamic] -ddump-to-file Dump to files instead of stdout [dynamic] -ddump-asm Dump assembly [dynamic] -ddump-bcos Dump interpreter byte code [dynamic] -ddump-cmm Dump C-- output [dynamic] -ddump-core-stats Print a one-line summary of the size of the Core program at the end of the optimisation pipeline [dynamic] -ddump-cse Dump CSE output [dynamic] -ddump-deriv Dump deriving output [dynamic] -ddump-ds Dump desugarer output [dynamic] -ddump-foreign Dump foreign export stubs [dynamic] -ddump-hpc Dump after instrumentation for program coverage [dynamic] -ddump-inlinings Dump inlining info [dynamic] -ddump-llvm Dump LLVM intermediate code [dynamic] -ddump-occur-anal Dump occurrence analysis output [dynamic] -ddump-opt-cmm Dump the results of C-- to C-- optimising passes [dynamic] -ddump-parsed Dump parse tree [dynamic] -ddump-prep Dump prepared core [dynamic] -ddump-rn Dump renamer output [dynamic] -ddump-rule-firings Dump rule firing info [dynamic] -ddump-rule-rewrites Dump detailed rule firing info [dynamic] -ddump-rules Dump rules [dynamic] -ddump-vect Dump vectoriser input and output [dynamic] -ddump-simpl Dump final simplifier output [dynamic] -ddump-simpl-iterations Dump output from each simplifier iteration [dynamic] -ddump-spec Dump specialiser output [dynamic] -ddump-splices Dump TH spliced expressions, and what they evaluate to [dynamic] -ddump-stg Dump final STG [dynamic] -ddump-stranal Dump strictness analyser output [dynamic] -ddump-strsigs Dump strictness signatures [dynamic] -ddump-tc Dump typechecker output [dynamic] -dth-dec-file Show evaluated TH declarations in a .th.hs file [dynamic] -ddump-types Dump type signatures [dynamic] -ddump-worker-wrapper Dump worker-wrapper output [dynamic] -ddump-if-trace Trace interface files [dynamic] -ddump-tc-trace Trace typechecker [dynamic] -ddump-vt-trace Trace vectoriser [dynamic] -ddump-rn-trace Trace renamer [dynamic] -ddump-rn-stats Renamer stats [dynamic] -ddump-simpl-stats Dump simplifier stats [dynamic] -dno-debug-output Suppress unsolicited debugging output [static] -dppr-debug Turn on debug printing (more verbose) [static] -dppr-user-length Set the depth for printing expressions in error msgs [dynamic] -dppr-colsNNN Set the width of debugging output. For example -dppr-cols200 [dynamic] -dppr-case-as-let Print single alternative case expressions as strict lets. [dynamic] -dsuppress-all In core dumps, suppress everything (except for uniques) that is suppressible. [dynamic] -dsuppress-uniques Suppress the printing of uniques in debug output (easier to use diff) [dynamic] -dsuppress-idinfo Suppress extended information about identifiers where they are bound [dynamic] -dsuppress-module-prefixes Suppress the printing of module qualification prefixes [dynamic] -dsuppress-type-signatures Suppress type signatures [dynamic] -dsuppress-type-applications Suppress type applications [dynamic] -dsuppress-coercions Suppress the printing of coercions in Core dumps to make them shorter [dynamic] -dsource-stats Dump haskell source stats [dynamic] -dcmm-lint C-- pass sanity checking [dynamic] -dstg-lint STG pass sanity checking [dynamic] -dstg-stats Dump STG stats [dynamic] -dverbose-core2core Show output from each core-to-core pass [dynamic] -dverbose-stg2stg Show output from each STG-to-STG pass [dynamic] -dshow-passes Print out each pass name as it happens [dynamic] -dfaststring-stats Show statistics for fast string usage when finished [dynamic] -frule-check Report sites with rules that could have fired but didn't. Takes a string argument. [dynamic]

MISC COMPILER OPTIONS

-jN When compiling with --make, compile N modules in parallel. [dynamic] -fno-hi-version-check Don't complain about .hi file mismatches [dynamic] -fhistory-size Set simplification history size [dynamic] -fno-ghci-history Do not use the load/store the GHCi command history from/to ghci_history. [dynamic] -fno-ghci-sandbox Turn off the GHCi sandbox. Means computations are run in the main thread, rather than a forked thread. [dynamic]

FILES

/usr/local/lib

COPYRIGHT

Copyright 2002, The University Court of the University of Glasgow. All rights reserved.

AUTHOR

This manual page was generated from the XML documentation of GHC with blood, sweat, tears and a breaks-if-you-look-at-it-the-wrong-way XSL stylesheet originally written by Michael Weber <michaelw@debian.org> for the Debian GNU/Linux system (but may be used by others). Glasgow FP Suite 2002-10-25 GHC(1)

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