1GHC(1) Glasgow Haskell Compiler GHC(1)
2
6 ghc - the Glasgow Haskell Compiler
7
9 ghc [option|filename]
10 ghci [option|filename]
11
13 This manual page documents briefly the ghc and ghci commands. Note that
14 ghci is not yet available on all architectures. Extensive documentation
15 is available in various other formats including PDF and HTML.
16 Each of GHC's command line options is classified as either static or
18 dynamic. A static flag may only be specified on the command line,
19 whereas a dynamic flag may also be given in an OPTIONS pragma in a
20 source file or set from the GHCi command-line with :set .
21 As a rule of thumb, all the language options are dynamic, as are the
23 warning options and the debugging options.
24 The rest are static, with the notable exceptions of -v, -cpp, -fasm,
26 -fvia-C, -fllvm, and -#include. The OPTIONS sections lists the status
27 of each flag.
28 Common suffixes of file names for Haskell are:
30 .hs Haskell source code; preprocess, compile
32 .lhs literate Haskell source; unlit, preprocess, compile
34 .hi Interface file; contains information about exported symbols
36 .hc intermediate C files
38 .⟨way⟩_o
40 object files for "way" ⟨way⟩; common ways are:
41 dyn dynamically-linked
43 p built with profiling
45 .⟨way⟩_hi
47 interface files for "way" ⟨way⟩; common ways are:
48
50 Code generation
51 -dynamic-too -fasm -fllvm -fbyte-code -fexternal-dynamic-refs
52 -fllvm -fasm -fno-code -fobject-code -fPIC -fPIE -fwrite-inter‐
53 face
54 Debugging the compiler
56 -dcmm-lint -dcore-lint -ddump-asm -ddump-asm-expanded
57 -ddump-asm-liveness -ddump-asm-native -ddump-asm-regalloc
58 -ddump-asm-regalloc-stages -ddump-asm-stats -ddump-bcos
59 -ddump-cfg-weights -ddump-cmm -ddump-cmm-caf -ddump-cmm-cbe
60 -ddump-cmm-cfg -ddump-cmm-cps -ddump-cmm-from-stg
61 -ddump-cmm-info -ddump-cmm-proc -ddump-cmm-procmap
62 -ddump-cmm-raw -ddump-cmm-sink -ddump-cmm-sp -ddump-cmm-split
63 -ddump-cmm-switch -ddump-cmm-verbose -ddump-cmm-verbose-by-proc
64 -ddump-core-stats -ddump-cse -ddump-deriv -ddump-ds
65 -ddump-ds-preopt -ddump-ec-trace -ddump-file-prefix=⟨str⟩
66 -ddump-foreign -ddump-hpc -ddump-if-trace -ddump-inlinings
67 -ddump-json -ddump-llvm -ddump-mod-map -ddump-occur-anal
68 -ddump-opt-cmm -ddump-parsed -ddump-parsed-ast -ddump-prep
69 -ddump-rn -ddump-rn-ast -ddump-rn-stats -ddump-rn-trace
70 -ddump-rtti -ddump-rule-firings -ddump-rule-rewrites
71 -ddump-rules -ddump-simpl -ddump-simpl-iterations
72 -ddump-simpl-stats -ddump-spec -ddump-splices -ddump-stg
73 -ddump-stg-final -ddump-stg-unarised -ddump-str-signatures
74 -ddump-stranal -ddump-tc -ddump-tc-ast -ddump-tc-trace
75 -ddump-ticked -ddump-timings -ddump-to-file -ddump-types
76 -ddump-worker-wrapper -dfaststring-stats -dhex-word-literals
77 -dinitial-unique=⟨s⟩ -dinline-check=⟨str⟩ -dno-debug-output
78 -ddebug-output -dno-typeable-binds -dppr-case-as-let
79 -dppr-cols=⟨n⟩ -dppr-debug -dppr-user-length -drule-check=⟨str⟩
80 -dshow-passes -dstg-lint -dsuppress-all -dsuppress-coercions
81 -dsuppress-idinfo -dsuppress-module-prefixes -dsup‐
82 press-stg-free-vars -dsuppress-ticks -dsuppress-timestamps
83 -dsuppress-type-applications -dsuppress-type-signatures -dsup‐
84 press-unfoldings -dsuppress-uniques -dsuppress-var-kinds
85 -dth-dec-file -dunique-increment=⟨i⟩ -dverbose-core2core -dver‐
86 bose-stg2stg -falignment-sanitisation -fcatch-bottoms
87 -fllvm-fill-undef-with-garbage -fproc-alignment -g -g⟨n⟩
88 C pre-processor
90 -cpp -D⟨symbol⟩[=⟨value⟩] -U⟨symbol⟩ -I⟨dir⟩ -U⟨symbol⟩
91 Finding imports
93 -i -i⟨dir⟩[:⟨dir⟩]*
94 Interactive mode
96 -fbreak-on-error -fno-break-on-error -fbreak-on-exception
97 -fno-break-on-exception -fghci-hist-size=⟨n⟩ -fghci-leak-check
98 -fno-ghci-leak-check -flocal-ghci-history -fno-local-ghci-his‐
99 tory -fno-it -fno-no-it -fprint-bind-result -fno-print-bind-re‐
100 sult -fprint-evld-with-show -fshow-loaded-modules -ghci-script
101 -ignore-dot-ghci -interactive-print ⟨name⟩
102 Interface files
104 --show-iface ⟨file⟩ -ddump-hi -ddump-hi-diffs -ddump-minimal-im‐
105 ports
106 Keeping intermediate files
108 -keep-hc-file -keep-hc-files -keep-hi-files -no-keep-hi-files
109 -keep-hscpp-file -keep-hscpp-files -keep-llvm-file
110 -keep-llvm-files -keep-o-files -no-keep-o-files -keep-s-file
111 -keep-s-files -keep-tmp-files
112 Language options
114 -fno-safe-haskell -fsort-by-size-hole-fits
115 -fno-sort-by-size-hole-fits -fsort-by-subsumption-hole-fits
116 -fno-sort-by-subsumption-hole-fits -XAllowAmbiguousTypes -XAp‐
117 plicativeDo -XArrows -XBangPatterns -XBinaryLiterals -XBlockAr‐
118 guments -XCApiFFI -XConstrainedClassMethods -XConstraintKinds
119 -XCPP -XCUSKs -XDataKinds -XDatatypeContexts -XDefaultSignatures
120 -XDeriveAnyClass -XDeriveDataTypeable -XDeriveFoldable -XDerive‐
121 Functor -XDeriveGeneric -XDeriveLift -XDeriveTraversable
122 -XDerivingStrategies -XDerivingVia -XDisambiguateRecordFields
123 -XDuplicateRecordFields -XEmptyCase -XEmptyDataDecls -XEmpty‐
124 DataDeriving -XExistentialQuantification -XExplicitForAll -XEx‐
125 plicitNamespaces -XExtendedDefaultRules -XFlexibleContexts
126 -XFlexibleInstances -XForeignFunctionInterface -XFunctionalDe‐
127 pendencies -XGADTs -XGADTSyntax -XGeneralisedNewtypeDeriving
128 -XGeneralizedNewtypeDeriving -XGHCForeignImportPrim
129 -XHaskell2010 -XHaskell98 -XHexFloatLiterals -XImplicitParams
130 -XImportQualifiedPost -XImpredicativeTypes -XIncoherentInstances
131 -XInstanceSigs -XInterruptibleFFI -XKindSignatures -XLambdaCase
132 -XLiberalTypeSynonyms -XMagicHash -XMonadComprehensions -XMonad‐
133 FailDesugaring -XMonoLocalBinds -XMultiParamTypeClasses -XMulti‐
134 WayIf -XNamedFieldPuns -XNamedWildCards -XNegativeLiterals
135 -XNoImplicitPrelude -XNoMonomorphismRestriction -XNonde‐
136 creasingIndentation -XNoPatternGuards -XNoTraditionalRecordSyn‐
137 tax -XNPlusKPatterns -XNullaryTypeClasses -XNumDecimals -XNumer‐
138 icUnderscores -XOverlappingInstances -XOverloadedLabels -XOver‐
139 loadedLists -XOverloadedStrings -XPackageImports -XParallelList‐
140 Comp -XPartialTypeSignatures -XPatternSynonyms -XPolyKinds
141 -XPostfixOperators -XQuantifiedConstraints -XQuasiQuotes
142 -XRank2Types -XRankNTypes -XRebindableSyntax -XRecordWildCards
143 -XRecursiveDo -XRoleAnnotations -XSafe -XScopedTypeVariables
144 -XStandaloneDeriving -XStandaloneKindSignatures -XStarIsType
145 -XStaticPointers -XStrict -XStrictData -XTemplateHaskell -XTem‐
146 plateHaskellQuotes -XTransformListComp -XTrustworthy -XTupleSec‐
147 tions -XTypeApplications -XTypeFamilies -XTypeFamilyDependencies
148 -XTypeInType -XTypeOperators -XTypeSynonymInstances -XUnboxed‐
149 Sums -XUnboxedTuples -XUndecidableInstances -XUndecidableSuper‐
150 Classes -XUnicodeSyntax -XUnliftedFFITypes -XUnliftedNewtypes
151 -XUnsafe -XViewPatterns
152 Linking options
154 -c -debug -dylib-install-name ⟨path⟩ -dynamic -dynload -eventlog
155 -flink-rts -fno-embed-manifest -fno-gen-manifest -fno-shared-im‐
156 plib -framework ⟨name⟩ -framework-path ⟨dir⟩ -fuse-rpaths
157 -fno-use-rpaths -fwhole-archive-hs-libs -keep-cafs -L ⟨dir⟩ -l
158 ⟨lib⟩ -main-is ⟨thing⟩ -no-hs-main -no-rtsopts-suggestions
159 -package ⟨name⟩ -pie -rdynamic -rtsopts[=⟨none|some|all|ig‐
160 nore|ignoreAll⟩] -shared -split-sections -static -staticlib
161 -threaded -with-rtsopts=⟨opts⟩
162 Miscellaneous options
164 -fexternal-interpreter -fglasgow-exts -fno-glasgow-exts -ghcver‐
165 sion-file ⟨path to ghcversion.h⟩ -H ⟨size⟩ -j[⟨n⟩]
166 Modes of operation
168 --frontend ⟨module⟩ --help -? --info --interactive --make
169 --mk-dll --numeric-version --print-libdir --show-iface ⟨file⟩
170 --show-options --supported-extensions --supported-languages
171 --version -V -e ⟨expr⟩ -M
172 Individual optimizations
174 -fasm-shortcutting -fno-asm-shortcutting -fbinary-blob-thresh‐
175 old=⟨n⟩ -fblock-layout-cfg -fno-block-layout-cfg -fblock-lay‐
176 out-weightless -fno-block-layout-weightless -fblock-lay‐
177 out-weights -fcall-arity -fno-call-arity -fcase-folding
178 -fno-case-folding -fcase-merge -fno-case-merge -fcmm-elim-com‐
179 mon-blocks -fno-cmm-elim-common-blocks -fcmm-sink -fno-cmm-sink
180 -fcpr-anal -fno-cpr-anal -fcross-module-specialise
181 -fno-cross-module-specialise -fcse -fno-cse -fdicts-cheap
182 -fno-dicts-cheap -fdicts-strict -fno-dicts-strict
183 -fdmd-tx-dict-sel -fno-dmd-tx-dict-sel -fdo-eta-reduction
184 -fno-do-eta-reduction -fdo-lambda-eta-expansion
185 -fno-do-lambda-eta-expansion -feager-blackholing -fenable-re‐
186 write-rules -fno-enable-rewrite-rules -fexcess-precision
187 -fno-excess-precision -fexitification -fno-exitification -fex‐
188 pose-all-unfoldings -fno-expose-all-unfoldings -ffloat-in
189 -fno-float-in -ffull-laziness -fno-full-laziness -ffun-to-thunk
190 -fno-fun-to-thunk -fignore-asserts -fno-ignore-asserts -fig‐
191 nore-interface-pragmas -fno-ignore-interface-pragmas
192 -flate-dmd-anal -fno-late-dmd-anal -flate-specialise
193 -fno-late-specialise -fliberate-case -fno-liberate-case -fliber‐
194 ate-case-threshold=⟨n⟩ -fno-liberate-case-threshold
195 -fllvm-pass-vectors-in-regs -fno-llvm-pass-vectors-in-regs
196 -floopification -fno-loopification -fmax-inline-alloc-size=⟨n⟩
197 -fmax-inline-memcpy-insns=⟨n⟩ -fmax-inline-memset-insns=⟨n⟩
198 -fmax-simplifier-iterations=⟨n⟩ -fmax-uncovered-patterns=⟨n⟩
199 -fmax-worker-args=⟨n⟩ -fno-opt-coercion -fno-pre-inlining
200 -fno-state-hack -fomit-interface-pragmas -fno-omit-inter‐
201 face-pragmas -fomit-yields -fno-omit-yields -foptimal-applica‐
202 tive-do -fno-optimal-applicative-do -fpedantic-bottoms
203 -fno-pedantic-bottoms -fregs-graph -fno-regs-graph -fregs-itera‐
204 tive -fno-regs-iterative -fsimpl-tick-factor=⟨n⟩ -fsimpli‐
205 fier-phases=⟨n⟩ -fsolve-constant-dicts -fno-solve-constant-dicts
206 -fspec-constr -fno-spec-constr -fspec-constr-count=⟨n⟩
207 -fno-spec-constr-count -fspec-constr-keen -fno-spec-constr-keen
208 -fspec-constr-threshold=⟨n⟩ -fno-spec-constr-threshold -fspe‐
209 cialise -fno-specialise -fspecialise-aggressively -fno-spe‐
210 cialise-aggressively -fstatic-argument-transformation
211 -fno-static-argument-transformation -fstg-cse -fno-stg-cse
212 -fstg-lift-lams -fno-stg-lift-lams -fstg-lift-lams-known
213 -fno-stg-lift-lams-known -fstg-lift-lams-non-rec-args
214 -fno-stg-lift-lams-non-rec-args-any -fstg-lift-lams-rec-args
215 -fno-stg-lift-lams-rec-args-any -fstrictness -fno-strictness
216 -fstrictness-before=⟨n⟩ -funbox-small-strict-fields -fno-un‐
217 box-small-strict-fields -funbox-strict-fields -fno-un‐
218 box-strict-fields -funfolding-creation-threshold=⟨n⟩ -funfold‐
219 ing-dict-discount=⟨n⟩ -funfolding-fun-discount=⟨n⟩ -funfold‐
220 ing-keeness-factor=⟨n⟩ -funfolding-use-threshold=⟨n⟩
221 -fworker-wrapper
222 Optimization levels
224 -O -O1 -O0 -O0 -O2 -O0 -O⟨n⟩ -O0
225 Package options
227 -clear-package-db -distrust ⟨pkg⟩ -distrust-all-packages -fpack‐
228 age-trust -global-package-db -hide-all-packages -hide-package
229 ⟨pkg⟩ -ignore-package ⟨pkg⟩ -no-auto-link-packages
230 -no-global-package-db -no-user-package-db -package ⟨pkg⟩ -pack‐
231 age-db ⟨file⟩ -package-env ⟨file⟩|⟨name⟩ -package-id ⟨unit-id⟩
232 -this-unit-id ⟨unit-id⟩ -trust ⟨pkg⟩ -user-package-db
233 Phases of compilation
235 -C -c -E -F -S -x ⟨suffix⟩
236 Overriding external programs
238 -pgma ⟨cmd⟩ -pgmc ⟨cmd⟩ -pgmdll ⟨cmd⟩ -pgmF ⟨cmd⟩ -pgmi ⟨cmd⟩
239 -pgminstall_name_tool ⟨cmd⟩ -pgmL ⟨cmd⟩ -pgml ⟨cmd⟩ -pgmlc ⟨cmd⟩
240 -pgmlibtool ⟨cmd⟩ -pgmlm ⟨cmd⟩ -pgmlo ⟨cmd⟩ -pgmotool ⟨cmd⟩
241 -pgmP ⟨cmd⟩ -pgms ⟨cmd⟩ -pgmwindres ⟨cmd⟩
242 Phase-specific options
244 -opta ⟨option⟩ -optc ⟨option⟩ -optcxx ⟨option⟩ -optdll ⟨option⟩
245 -optF ⟨option⟩ -opti ⟨option⟩ -optL ⟨option⟩ -optl ⟨option⟩
246 -optlc ⟨option⟩ -optlm ⟨option⟩ -optlo ⟨option⟩ -optP ⟨option⟩
247 -optwindres ⟨option⟩ -pgmc-supports-no-pie
248 Platform-specific options
250 -mbmi2 -msse2 -msse4.2
251 Compiler plugins
253 -fclear-plugins -fplugin-opt=⟨module⟩:⟨args⟩ -fplugin-trustwor‐
254 thy -fplugin=⟨module⟩ -hide-all-plugin-packages -plugin-package
255 ⟨pkg⟩ -plugin-package-id ⟨pkg-id⟩
256 Profiling
258 -fno-prof-auto -fprof-auto -fno-prof-cafs -fprof-cafs
259 -fno-prof-count-entries -fprof-count-entries -fprof-auto
260 -fno-prof-auto -fprof-auto-calls -fno-prof-auto-calls
261 -fprof-auto-exported -fno-prof-auto -fprof-auto-top
262 -fno-prof-auto -fprof-cafs -fno-prof-cafs -prof -ticky
263 Program coverage
265 -fhpc
266 Recompilation checking
268 -fforce-recomp -fno-force-recomp -fignore-hpc-changes -fno-ig‐
269 nore-hpc-changes -fignore-optim-changes -fno-ignore-op‐
270 tim-changes
271 Redirecting output
273 --exclude-module=⟨file⟩ -ddump-mod-cycles -dep-makefile ⟨file⟩
274 -dep-suffix ⟨suffix⟩ -dumpdir ⟨dir⟩ -hcsuf ⟨suffix⟩ -hidir ⟨dir⟩
275 -hiedir ⟨dir⟩ -hiesuf ⟨suffix⟩ -hisuf ⟨suffix⟩ -include-cpp-deps
276 -include-pkg-deps -o ⟨file⟩ -odir ⟨dir⟩ -ohi ⟨file⟩ -osuf ⟨suf‐
277 fix⟩ -outputdir ⟨dir⟩ -stubdir ⟨dir⟩
278 Temporary files
280 -tmpdir ⟨dir⟩
281 Verbosity options
283 -fabstract-refinement-hole-fits -fno-abstract-refine‐
284 ment-hole-fits -fdefer-diagnostics -fdiagnostics-color=⟨al‐
285 ways|auto|never⟩ -fdiagnostics-show-caret -fno-diagnos‐
286 tics-show-caret -ferror-spans -fhide-source-paths -fkeep-going
287 -fmax-refinement-hole-fits=⟨n⟩ -fno-max-refinement-hole-fits
288 -fmax-relevant-binds=⟨n⟩ -fno-max-relevant-binds
289 -fmax-valid-hole-fits=⟨n⟩ -fno-max-valid-hole-fits
290 -fno-show-valid-hole-fits -fno-sort-valid-hole-fits
291 -fsort-valid-hole-fits -fprint-axiom-incomps -fno-print-ax‐
292 iom-incomps -fprint-equality-relations -fno-print-equality-rela‐
293 tions -fprint-expanded-synonyms -fno-print-expanded-synonyms
294 -fprint-explicit-coercions -fno-print-explicit-coercions
295 -fprint-explicit-foralls -fno-print-explicit-foralls -fprint-ex‐
296 plicit-kinds -fno-print-explicit-kinds -fprint-explicit-run‐
297 time-reps -fno-print-explicit-runtime-reps -fprint-potential-in‐
298 stances -fno-print-potential-instances -fprint-typechecker-elab‐
299 oration -fno-print-typechecker-elaboration -fprint-unicode-syn‐
300 tax -fno-print-unicode-syntax -frefinement-level-hole-fits=⟨n⟩
301 -fno-refinement-level-hole-fits -freverse-errors -fno-re‐
302 verse-errors -fshow-docs-of-hole-fits
303 -fno-show-docs-of-hole-fits -fshow-hole-constraints
304 -fshow-hole-matches-of-hole-fits
305 -fno-show-hole-matches-of-hole-fits -fshow-prove‐
306 nance-of-hole-fits -fno-show-provenance-of-hole-fits
307 -fshow-type-app-of-hole-fits -fno-show-type-app-of-hole-fits
308 -fshow-type-app-vars-of-hole-fits
309 -fno-show-type-app-vars-of-hole-fits -fshow-type-of-hole-fits
310 -fno-type-of-hole-fits -funclutter-valid-hole-fits -Rghc-timing
311 -v -v⟨n⟩
312 Warnings
314 -fdefer-out-of-scope-variables -fno-defer-out-of-scope-variables
315 -fdefer-type-errors -fno-defer-type-errors -fdefer-typed-holes
316 -fno-defer-typed-holes -fenable-th-splice-warnings -fno-en‐
317 able-th-splices -fhelpful-errors -fno-helpful-errors -fmax-pm‐
318 check-models=⟨n⟩ -fshow-warning-groups -fno-show-warning-groups
319 -fvia-C -W -w -w -Wall -w -Wall-missed-specialisations
320 -Wno-all-missed-specialisations -Wauto-orphans -Wcompat
321 -Wno-compat -Wcompat-unqualified-imports -Wno-compat-unquali‐
322 fied-imports -Wcpp-undef -Wdefault -Wdeferred-out-of-scope-vari‐
323 ables -Wno-deferred-out-of-scope-variables -Wdeferred-type-er‐
324 rors -Wno-deferred-type-errors -Wdeprecated-flags -Wno-depre‐
325 cated-flags -Wdeprecations -Wno-deprecations -Wderiving-defaults
326 -Wno-deriving-defaults -Wderiving-typeable -Wno-deriving-ty‐
327 peable -Wdodgy-exports -Wno-dodgy-exports -Wdodgy-foreign-im‐
328 ports -Wno-dodgy-foreign-import -Wdodgy-imports -Wno-dodgy-im‐
329 ports -Wduplicate-constraints -Wno-duplicate-constraints -Wdu‐
330 plicate-exports -Wno-duplicate-exports -Wempty-enumerations
331 -Wno-empty-enumerations -Werror -Wwarn -Weverything -Whi-shadow‐
332 ing -Wno-hi-shadowing -Widentities -Wno-identities -Wim‐
333 plicit-kind-vars -Wno-implicit-kind-vars -Wimplicit-prelude
334 -Wno-implicit-prelude -Winaccessible-code -Wno-inaccessible-code
335 -Wincomplete-patterns -Wno-incomplete-patterns -Wincom‐
336 plete-record-updates -Wno-incomplete-record-updates -Wincom‐
337 plete-uni-patterns -Wno-incomplete-uni-patterns -Win‐
338 ferred-safe-imports -Wno-inferred-safe-imports -Win‐
339 line-rule-shadowing -Wno-inline-rule-shadowing -Wmissed-ex‐
340 tra-shared-lib -Wno-missed-extra-shared-lib -Wmissed-specialisa‐
341 tions -Wno-missed-specialisations -Wmissing-deriving-strategies
342 -Wno-missing-deriving-strategies -Wmissing-export-lists
343 -fnowarn-missing-export-lists -Wmissing-exported-signatures
344 -Wno-missing-exported-signatures -Wmissing-exported-sigs
345 -Wno-missing-exported-sigs -Wmissing-fields -Wno-missing-fields
346 -Wmissing-home-modules -Wno-missing-home-modules -Wmissing-im‐
347 port-lists -fnowarn-missing-import-lists -Wmissing-local-signa‐
348 tures -Wno-missing-local-signatures -Wmissing-local-sigs
349 -Wno-missing-local-sigs -Wmissing-methods -Wno-missing-methods
350 -Wmissing-monadfail-instances -Wno-missing-monadfail-instances
351 -Wmissing-pattern-synonym-signatures -Wno-missing-pattern-syn‐
352 onym-signatures -Wmissing-safe-haskell-mode -Wno-miss‐
353 ing-safe-haskell-mode -Wmissing-signatures -Wno-missing-signa‐
354 tures -Wmissing-space-after-bang -Wmonomorphism-restriction
355 -Wno-monomorphism-restriction -Wname-shadowing -Wno-name-shadow‐
356 ing -Wno-compat -Wcompat -Wnoncanonical-monad-instances
357 -Wno-noncanonical-monad-instances -Wnoncanonical-monadfail-in‐
358 stances -Wno-noncanonical-monadfail-instances -Wnoncanoni‐
359 cal-monoid-instances -Wno-noncanonical-monoid-instances -Wor‐
360 phans -Wno-orphans -Woverflowed-literals -Wno-overflowed-liter‐
361 als -Woverlapping-patterns -Wno-overlapping-patterns -Wpar‐
362 tial-fields -Wno-partial-fields -Wpartial-type-signatures
363 -Wno-partial-type-signatures -Wredundant-constraints -Wno-redun‐
364 dant-constraints -Wredundant-record-wildcards -Wno-redun‐
365 dant-record-wildcards -Wsafe -Wno-safe -Wsemigroup -Wno-semi‐
366 group -Wsimplifiable-class-constraints -Wno-simplifi‐
367 able-class-constraints -Wspace-after-bang -Wno-missing-space-af‐
368 ter-bang -Wstar-binder -Wno-star-binder -Wstar-is-type
369 -Wno-star-is-type -Wtabs -Wno-tabs -Wtrustworthy-safe -Wno-safe
370 -Wtype-defaults -Wno-type-defaults -Wtyped-holes
371 -Wno-typed-holes -Wunbanged-strict-patterns -Wno-un‐
372 banged-strict-patterns -Wunrecognised-pragmas -Wno-unrecog‐
373 nised-pragmas -Wunrecognised-warning-flags -Wno-unrecog‐
374 nised-warning-flags -Wunsafe -Wno-unsafe -Wunsupported-call‐
375 ing-conventions -Wno-unsupported-calling-conventions -Wunsup‐
376 ported-llvm-version -Wno-monomorphism-restriction
377 -Wunticked-promoted-constructors -Wno-unticked-promoted-con‐
378 structors -Wunused-binds -Wno-unused-binds -Wunused-do-bind
379 -Wno-unused-do-bind -Wunused-foralls -Wno-unused-foralls
380 -Wunused-imports -Wno-unused-imports -Wunused-local-binds
381 -Wno-unused-local-binds -Wunused-matches -Wno-unused-matches
382 -Wunused-packages -Wno-unused-packages -Wunused-pattern-binds
383 -Wno-unused-pattern-binds -Wunused-record-wildcards -Wno-un‐
384 used-record-wildcards -Wunused-top-binds -Wno-unused-top-binds
385 -Wunused-type-patterns -Wno-unused-type-patterns -Wwarn -Werror
386 -Wwarnings-deprecations -Wno-warnings-deprecations
387 -Wwrong-do-bind -Wno-wrong-do-bind
388 Code generation
390 -dynamic-too
391 Build dynamic object files as well as static object files during
392 compilation
393 -fasm Use the native code generator
395 -fbyte-code
397 Generate byte-code
398 -fexternal-dynamic-refs
400 Generate code for linking against dynamic libraries
401 -fllvm Compile using the LLVM code generator
403 -fno-code
405 Omit code generation
406 -fobject-code
408 Generate object code
409 -fPIC Generate position-independent code (where available)
411 -fPIE Generate code for a position-independent executable (where
413 available)
414 -fwrite-interface
416 Always write interface files
417 Debugging the compiler
419 -dcmm-lint
420 C-\- pass sanity checking
421 -dcore-lint
423 Turn on internal sanity checking
424 -ddump-asm
426 Dump final assembly
427 -ddump-asm-expanded
429 Dump the result of the synthetic instruction expansion pass.
430 -ddump-asm-liveness
432 Dump assembly augmented with register liveness
433 -ddump-asm-native
435 Dump initial assembly
436 -ddump-asm-regalloc
438 Dump the result of register allocation
439 -ddump-asm-regalloc-stages
441 Dump the build/spill stages of the -fregs-graph register alloca‐
442 tor.
443 -ddump-asm-stats
445 Dump statistics from the register allocator.
446 -ddump-bcos
448 Dump interpreter byte code
449 -ddump-cfg-weights
451 Dump the assumed weights of the CFG.
452 -ddump-cmm
454 Dump the final C-\- output
455 -ddump-cmm-caf
457 Dump the results of the C-\- CAF analysis pass.
458 -ddump-cmm-cbe
460 Dump the results of common block elimination
461 -ddump-cmm-cfg
463 Dump the results of the C-\- control flow optimisation pass.
464 -ddump-cmm-cps
466 Dump the results of the CPS pass
467 -ddump-cmm-from-stg
469 Dump STG-to-C-\- output
470 -ddump-cmm-info
472 Dump the results of the C-\- info table augmentation pass.
473 -ddump-cmm-proc
475 Dump the results of proc-point analysis
476 -ddump-cmm-procmap
478 Dump the results of the C-\- proc-point map pass.
479 -ddump-cmm-raw
481 Dump raw C-\-
482 -ddump-cmm-sink
484 Dump the results of the C-\- sinking pass.
485 -ddump-cmm-sp
487 Dump the results of the C-\- stack layout pass.
488 -ddump-cmm-split
490 Dump the results of the C-\- proc-point splitting pass.
491 -ddump-cmm-switch
493 Dump the results of switch lowering passes
494 -ddump-cmm-verbose
496 Write output from main C-\- pipeline passes to files
497 -ddump-cmm-verbose-by-proc
499 Show output from main C-\- pipeline passes (grouped by proc)
500 -ddump-core-stats
502 Print a one-line summary of the size of the Core program at the
503 end of the optimisation pipeline
504 -ddump-cse
506 Dump CSE output
507 -ddump-deriv
509 Dump deriving output
510 -ddump-ds
512 Dump desugarer output.
513 -ddump-ec-trace
515 Trace exhaustiveness checker
516 -ddump-file-prefix=⟨str⟩
518 Set the prefix of the filenames used for debugging output.
519 -ddump-foreign
521 Dump foreign export stubs
522 -ddump-hpc
524 An alias for -ddump-ticked.
525 -ddump-if-trace
527 Trace interface files
528 -ddump-inlinings
530 Dump inlining info
531 -ddump-json
533 Dump error messages as JSON documents
534 -ddump-llvm
536 Dump LLVM intermediate code.
537 -ddump-mod-map
539 Dump the state of the module mapping database.
540 -ddump-occur-anal
542 Dump occurrence analysis output
543 -ddump-opt-cmm
545 Dump the results of C-\- to C-\- optimising passes
546 -ddump-parsed
548 Dump parse tree
549 -ddump-parsed-ast
551 Dump parser output as a syntax tree
552 -ddump-prep
554 Dump prepared core
555 -ddump-rn
557 Dump renamer output
558 -ddump-rn-ast
560 Dump renamer output as a syntax tree
561 -ddump-rn-stats
563 Renamer stats
564 -ddump-rn-trace
566 Trace renamer
567 -ddump-rtti
569 Trace runtime type inference
570 -ddump-rule-firings
572 Dump rule firing info
573 -ddump-rule-rewrites
575 Dump detailed rule firing info
576 -ddump-rules
578 Dump rewrite rules
579 -ddump-simpl
581 Dump final simplifier output
582 -ddump-simpl-iterations
584 Dump output from each simplifier iteration
585 -ddump-simpl-stats
587 Dump simplifier stats
588 -ddump-spec
590 Dump specialiser output
591 -ddump-splices
593 Dump TH spliced expressions, and what they evaluate to
594 -ddump-stg
596 Show CoreToStg output
597 -ddump-stg-final
599 Show output of last STG pass.
600 -ddump-stg-unarised
602 Show unarised STG
603 -ddump-str-signatures
605 Dump strictness signatures
606 -ddump-stranal
608 Dump strictness analyser output
609 -ddump-tc
611 Dump typechecker output
612 -ddump-tc-ast
614 Dump typechecker output as a syntax tree
615 -ddump-tc-trace
617 Trace typechecker
618 -ddump-ticked
620 Dump the code instrumented by HPC (Observing Code Coverage).
621 -ddump-timings
623 Dump per-pass timing and allocation statistics
624 -ddump-to-file
626 Dump to files instead of stdout
627 -ddump-types
629 Dump type signatures
630 -ddump-worker-wrapper
632 Dump worker-wrapper output
633 -dfaststring-stats
635 Show statistics for fast string usage when finished
636 -dhex-word-literals
638 Print values of type Word# in hexadecimal.
639 -dinitial-unique=⟨s⟩
641 Start UniqSupply allocation from ⟨s⟩.
642 -dinline-check=⟨str⟩
644 Dump information about inlining decisions
645 -dno-debug-output
647 Suppress unsolicited debugging output
648 -dno-typeable-binds
650 Don't generate bindings for Typeable methods
651 -dppr-case-as-let
653 Print single alternative case expressions as strict lets.
654 -dppr-cols=⟨n⟩
656 Set the width of debugging output. For example -dppr-cols200
657 -dppr-debug
659 Turn on debug printing (more verbose)
660 -dppr-user-length
662 Set the depth for printing expressions in error msgs
663 -drule-check=⟨str⟩
665 Dump information about potential rule application
666 -dshow-passes
668 Print out each pass name as it happens
669 -dstg-lint
671 STG pass sanity checking
672 -dsuppress-all
674 In dumps, suppress everything (except for uniques) that is sup‐
675 pressible.
676 -dsuppress-coercions
678 Suppress the printing of coercions in Core dumps to make them
679 shorter
680 -dsuppress-idinfo
682 Suppress extended information about identifiers where they are
683 bound
684 -dsuppress-module-prefixes
686 Suppress the printing of module qualification prefixes
687 -dsuppress-stg-free-vars
689 Suppress the printing of closure free variable lists in STG out‐
690 put
691 -dsuppress-ticks
693 Suppress "ticks" in the pretty-printer output.
694 -dsuppress-timestamps
696 Suppress timestamps in dumps
697 -dsuppress-type-applications
699 Suppress type applications
700 -dsuppress-type-signatures
702 Suppress type signatures
703 -dsuppress-unfoldings
705 Suppress the printing of the stable unfolding of a variable at
706 its binding site
707 -dsuppress-uniques
709 Suppress the printing of uniques in debug output (easier to use
710 diff)
711 -dsuppress-var-kinds
713 Suppress the printing of variable kinds
714 -dth-dec-file
716 Dump evaluated TH declarations into *.th.hs files
717 -dunique-increment=⟨i⟩
719 Set the increment for the generated Unique's to ⟨i⟩.
720 -dverbose-core2core
722 Show output from each core-to-core pass
723 -dverbose-stg2stg
725 Show output from each STG-to-STG pass
726 -falignment-sanitisation
728 Compile with alignment checks for all info table dereferences.
729 -fcatch-bottoms
731 Insert error expressions after bottoming expressions; useful
732 when debugging the compiler.
733 -fllvm-fill-undef-with-garbage
735 Intruct LLVM to fill dead STG registers with garbage
736 -fproc-alignment
738 Align functions at given boundary.
739 -g Produce DWARF debug information in compiled object files. ⟨n⟩
741 can be 0, 1, or 2, with higher numbers producing richer output.
742 If ⟨n⟩ is omitted, level 2 is assumed.
743 C pre-processor
745 -cpp Run the C pre-processor on Haskell source files
746 -D⟨symbol⟩[=⟨value⟩]
748 Define a symbol in the C pre-processor
749 -I⟨dir⟩
751 Add ⟨dir⟩ to the directory search list for #include files
752 -U⟨symbol⟩
754 Undefine a symbol in the C pre-processor
755 Finding imports
757 -i Empty the import directory list
758 -i⟨dir⟩[:⟨dir⟩]*
760 add ⟨dir⟩, ⟨dir2⟩, etc. to import path
761 Interactive mode
763 -fbreak-on-error
764 Break on uncaught exceptions and errors
765 -fbreak-on-exception
767 Break on any exception thrown
768 -fghci-hist-size=⟨n⟩
770 Set the number of entries GHCi keeps for :history. See The GHCi
771 Debugger.
772 -fghci-leak-check
774 (Debugging only) check for space leaks when loading new modules
775 in GHCi.
776 -flocal-ghci-history
778 Use current directory for the GHCi command history file
779 .ghci-history.
780 -fno-it
782 No longer set the special variable it.
783 -fprint-bind-result
785 Turn on printing of binding results in GHCi
786 -fprint-evld-with-show
788 Instruct :print to use Show instances where possible.
789 -fshow-loaded-modules
791 Show the names of modules that GHCi loaded after a :load com‐
792 mand.
793 -ghci-script
795 Read additional .ghci files
796 -ignore-dot-ghci
798 Disable reading of .ghci files
799 -interactive-print ⟨name⟩
801 Select the function to use for printing evaluated expressions in
802 GHCi
803 Interface files
805 --show-iface ⟨file⟩
806 See Modes of operation.
807 -ddump-hi
809 Dump the new interface to stdout
810 -ddump-hi-diffs
812 Show the differences vs. the old interface
813 -ddump-minimal-imports
815 Dump a minimal set of imports
816 Keeping intermediate files
818 -keep-hc-file
819 Retain intermediate .hc files.
820 -keep-hi-files
822 Retain intermediate .hi files (the default).
823 -keep-hscpp-file
825 Retain intermediate .hscpp files.
826 -keep-llvm-file
828 Retain intermediate LLVM .ll files. Implies -fllvm.
829 -keep-o-files
831 Retain intermediate .o files (the default).
832 -keep-s-file
834 Retain intermediate .s files.
835 -keep-tmp-files
837 Retain all intermediate temporary files.
838 Language options
840 -fno-safe-haskell
841 Disable Safe Haskell
842 -fsort-by-size-hole-fits
844 Sort valid hole fits by size.
845 -fsort-by-subsumption-hole-fits
847 Sort valid hole fits by subsumption.
848 -XAllowAmbiguousTypes
850 Allow the user to write ambiguous types, and the type inference
851 engine to infer them.
852 -XApplicativeDo
854 Enable Applicative do-notation desugaring
855 -XArrows
857 Enable arrow notation extension
858 -XBangPatterns
860 Enable bang patterns.
861 -XBinaryLiterals
863 Enable support for binary literals.
864 -XBlockArguments
866 Allow do blocks and other constructs as function arguments.
867 -XCApiFFI
869 Enable the CAPI calling convention.
870 -XConstrainedClassMethods
872 Enable constrained class methods.
873 -XConstraintKinds
875 Enable a kind of constraints.
876 -XCPP Enable the C preprocessor.
878 -XCUSKs
880 Enable detection of complete user-supplied kind signatures.
881 -XDataKinds
883 Enable datatype promotion.
884 -XDatatypeContexts
886 Allow contexts on data types.
887 -XDefaultSignatures
889 Enable default signatures.
890 -XDeriveAnyClass
892 Enable deriving for any class.
893 -XDeriveDataTypeable
895 Enable deriving for the Data class. Implied by (deprecated) Au‐
896 toDeriveTypeable.
897 -XDeriveFoldable
899 Enable deriving for the Foldable class. Implied by Derive‐
900 Traversable.
901 -XDeriveFunctor
903 Enable deriving for the Functor class. Implied by Derive‐
904 Traversable.
905 -XDeriveGeneric
907 Enable deriving for the Generic class.
908 -XDeriveLift
910 Enable deriving for the Lift class
911 -XDeriveTraversable
913 Enable deriving for the Traversable class. Implies DeriveFunc‐
914 tor and DeriveFoldable.
915 -XDerivingStrategies
917 Enables deriving strategies.
918 -XDerivingVia
920 Enable deriving instances via types of the same runtime repre‐
921 sentation. Implies DerivingStrategies.
922 -XDisambiguateRecordFields
924 Enable record field disambiguation. Implied by RecordWildCards.
925 -XDuplicateRecordFields
927 Allow definition of record types with identically-named fields.
928 -XEmptyCase
930 Allow empty case alternatives.
931 -XEmptyDataDecls
933 Allow definition of empty data types.
934 -XEmptyDataDeriving
936 Allow deriving instances of standard type classes for empty data
937 types.
938 -XExistentialQuantification
940 Enable liberalised type synonyms.
941 -XExplicitForAll
943 Enable explicit universal quantification. Implied by Scoped‐
944 TypeVariables, LiberalTypeSynonyms, RankNTypes and Existen‐
945 tialQuantification.
946 -XExplicitNamespaces
948 Enable using the keyword type to specify the namespace of en‐
949 tries in imports and exports (Explicit namespaces in import/ex‐
950 port). Implied by TypeOperators and TypeFamilies.
951 -XExtendedDefaultRules
953 Use GHCi's extended default rules in a normal module.
954 -XFlexibleContexts
956 Enable flexible contexts.
957 -XFlexibleInstances
959 Enable flexible instances. Implies TypeSynonymInstances.
960 -XForeignFunctionInterface
962 Enable foreign function interface.
963 -XFunctionalDependencies
965 Enable functional dependencies. Implies MultiParamTypeClasses.
966 -XGADTs
968 Enable generalised algebraic data types. Implies GADTSyntax and
969 MonoLocalBinds.
970 -XGADTSyntax
972 Enable generalised algebraic data type syntax.
973 -XGeneralisedNewtypeDeriving
975 Enable newtype deriving.
976 -XGeneralizedNewtypeDeriving
978 Enable newtype deriving.
979 -XGHCForeignImportPrim
981 Enable prim calling convention. Intended for internal use only.
982 -XHaskell2010
984 Use the Haskell 2010 language variant.
985 -XHaskell98
987 Use the Haskell 2010 language variant.
988 -XHexFloatLiterals
990 Enable support for hexadecimal floating point literals.
991 -XImplicitParams
993 Enable Implicit Parameters.
994 -XImportQualifiedPost
996 ImportQualifiedPost allows the syntax import M qualified
997 -XImpredicativeTypes
999 Enable impredicative types. Implies RankNTypes.
1000 -XIncoherentInstances
1002 Enable incoherent instances. Implies OverlappingInstances.
1003 -XInstanceSigs
1005 Enable instance signatures.
1006 -XInterruptibleFFI
1008 Enable interruptible FFI.
1009 -XKindSignatures
1011 Enable kind signatures. Implied by TypeFamilies and PolyKinds.
1012 -XLambdaCase
1014 Enable lambda-case expressions.
1015 -XLiberalTypeSynonyms
1017 Enable liberalised type synonyms.
1018 -XMagicHash
1020 Allow # as a postfix modifier on identifiers.
1021 -XMonadComprehensions
1023 Enable monad comprehensions.
1024 -XMonadFailDesugaring
1026 Enable monadfail desugaring.
1027 -XMonoLocalBinds
1029 Enable do not generalise local bindings. Implied by TypeFami‐
1030 lies and GADTs.
1031 -XMultiParamTypeClasses
1033 Enable multi parameter type classes. Implied by FunctionalDe‐
1034 pendencies.
1035 -XMultiWayIf
1037 Enable multi-way if-expressions.
1038 -XNamedFieldPuns
1040 Enable record puns.
1041 -XNamedWildCards
1043 Enable named wildcards.
1044 -XNegativeLiterals
1046 Enable support for negative literals.
1047 -XNoImplicitPrelude
1049 Don't implicitly import Prelude. Implied by RebindableSyntax.
1050 -XNoMonomorphismRestriction
1052 Disable the monomorphism restriction.
1053 -XNondecreasingIndentation
1055 Allow nested contexts to be at the same indentation level as its
1056 enclosing context.
1057 -XNoPatternGuards
1059 Disable pattern guards. Implied by Haskell98.
1060 -XNoTraditionalRecordSyntax
1062 Disable support for traditional record syntax (as supported by
1063 Haskell 98) C {f = x}
1064 -XNPlusKPatterns
1066 Enable support for n+k patterns. Implied by Haskell98.
1067 -XNullaryTypeClasses
1069 Deprecated, does nothing. nullary (no parameter) type classes
1070 are now enabled using MultiParamTypeClasses.
1071 -XNumDecimals
1073 Enable support for 'fractional' integer literals.
1074 -XNumericUnderscores
1076 Enable support for numeric underscores.
1077 -XOverlappingInstances
1079 Enable overlapping instances.
1080 -XOverloadedLabels
1082 Enable overloaded labels.
1083 -XOverloadedLists
1085 Enable overloaded lists.
1086 -XOverloadedStrings
1088 Enable overloaded string literals.
1089 -XPackageImports
1091 Enable package-qualified imports.
1092 -XParallelListComp
1094 Enable parallel list comprehensions.
1095 -XPartialTypeSignatures
1097 Enable partial type signatures.
1098 -XPatternSynonyms
1100 Enable pattern synonyms.
1101 -XPolyKinds
1103 Enable kind polymorphism. Implies KindSignatures.
1104 -XPostfixOperators
1106 Enable postfix operators.
1107 -XQuantifiedConstraints
1109 Allow forall quantifiers in constraints.
1110 -XQuasiQuotes
1112 Enable quasiquotation.
1113 -XRank2Types
1115 Enable rank-2 types. Synonym for RankNTypes.
1116 -XRankNTypes
1118 Enable rank-N types. Implied by ImpredicativeTypes.
1119 -XRebindableSyntax
1121 Employ rebindable syntax. Implies NoImplicitPrelude.
1122 -XRecordWildCards
1124 Enable record wildcards. Implies DisambiguateRecordFields.
1125 -XRecursiveDo
1127 Enable recursive do (mdo) notation.
1128 -XRoleAnnotations
1130 Enable role annotations.
1131 -XSafe Enable the Safe Haskell Safe mode.
1133 -XScopedTypeVariables
1135 Enable lexically-scoped type variables.
1136 -XStandaloneDeriving
1138 Enable standalone deriving.
1139 -XStandaloneKindSignatures
1141 Allow the use of standalone kind signatures.
1142 -XStarIsType
1144 Treat * as Data.Kind.Type.
1145 -XStaticPointers
1147 Enable static pointers.
1148 -XStrict
1150 Make bindings in the current module strict by default.
1151 -XStrictData
1153 Enable default strict datatype fields.
1154 -XTemplateHaskell
1156 Enable Template Haskell.
1157 -XTemplateHaskellQuotes
1159 Enable quotation subset of Template Haskell.
1160 -XTransformListComp
1162 Enable generalised list comprehensions.
1163 -XTrustworthy
1165 Enable the Safe Haskell Trustworthy mode.
1166 -XTupleSections
1168 Enable tuple sections.
1169 -XTypeApplications
1171 Enable type application syntax in terms and types.
1172 -XTypeFamilies
1174 Enable type families. Implies ExplicitNamespaces, KindSigna‐
1175 tures, and MonoLocalBinds.
1176 -XTypeFamilyDependencies
1178 Enable injective type families. Implies TypeFamilies.
1179 -XTypeInType
1181 Deprecated. Enable kind polymorphism and datatype promotion.
1182 -XTypeOperators
1184 Enable type operators. Implies ExplicitNamespaces.
1185 -XTypeSynonymInstances
1187 Enable type synonyms in instance heads. Implied by FlexibleIn‐
1188 stances.
1189 -XUnboxedSums
1191 Enable unboxed sums.
1192 -XUnboxedTuples
1194 Enable the use of unboxed tuple syntax.
1195 -XUndecidableInstances
1197 Enable undecidable instances.
1198 -XUndecidableSuperClasses
1200 Allow all superclass constraints, including those that may re‐
1201 sult in non-termination of the typechecker.
1202 -XUnicodeSyntax
1204 Enable unicode syntax.
1205 -XUnliftedFFITypes
1207 Enable unlifted FFI types
1208 -XUnliftedNewtypes
1210 Enable unlifted newtypes.
1211 -XUnsafe
1213 Enable Safe Haskell Unsafe mode.
1214 -XViewPatterns
1216 Enable view patterns.
1217 Linking options
1219 -c Stop after generating object (.o) file
1220 -debug Use the debugging runtime
1222 -dylib-install-name ⟨path⟩
1224 Set the install name (via -install_name passed to Apple's
1225 linker), specifying the full install path of the library file.
1226 Any libraries or executables that link with it later will pick
1227 up that path as their runtime search location for it. (Dar‐
1228 win/OS X only)
1229 -dynamic
1231 Build dynamically-linked object files and executables
1232 -dynload
1234 Selects one of a number of modes for finding shared libraries at
1235 runtime.
1236 -eventlog
1238 Enable runtime event tracing
1239 -flink-rts
1241 Link the runtime when generating a shared or static library
1242 -fno-embed-manifest
1244 Do not embed the manifest in the executable (Windows only)
1245 -fno-gen-manifest
1247 Do not generate a manifest file (Windows only)
1248 -fno-shared-implib
1250 Don't generate an import library for a DLL (Windows only)
1251 -framework ⟨name⟩
1253 On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This op‐
1254 tion corresponds to the -framework option for Apple's Linker.
1255 -framework-path ⟨dir⟩
1257 On Darwin/OS X/iOS only, add ⟨dir⟩ to the list of directories
1258 searched for frameworks. This option corresponds to the -F op‐
1259 tion for Apple's Linker.
1260 -fuse-rpaths
1262 Set the rpath based on -L flags
1263 -fwhole-archive-hs-libs
1265 When linking a binary executable, this inserts the flag
1266 -Wl,--whole-archive before any -l flags for Haskell libraries,
1267 and -Wl,--no-whole-archive afterwards
1268 -keep-cafs
1270 Do not garbage-collect CAFs (top-level expressions) at runtime
1271 -L ⟨dir⟩
1273 Add ⟨dir⟩ to the list of directories searched for libraries
1274 -l ⟨lib⟩
1276 Link in library ⟨lib⟩
1277 -main-is ⟨thing⟩
1279 Set main module and function
1280 -no-hs-main
1282 Don't assume this program contains main
1283 -no-rtsopts-suggestions
1285 Don't print RTS suggestions about linking with
1286 -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩].
1287 -package ⟨name⟩
1289 Expose package ⟨pkg⟩
1290 -pie Instruct the linker to produce a position-independent exe‐
1292 cutable.
1293 -rdynamic
1295 This instructs the linker to add all symbols, not only used
1296 ones, to the dynamic symbol table. Currently Linux and Win‐
1297 dows/MinGW32 only. This is equivalent to using -optl -rdynamic
1298 on Linux, and -optl -export-all-symbols on Windows.
1299 -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩]
1301 Control whether the RTS behaviour can be tweaked via com‐
1302 mand-line flags and the GHCRTS environment variable. Using none
1303 means no RTS flags can be given; some means only a minimum of
1304 safe options can be given (the default); all (or no argument at
1305 all) means that all RTS flags are permitted; ignore means RTS
1306 flags can be given, but are treated as regular arguments and
1307 passed to the Haskell program as arguments; ignoreAll is the
1308 same as ignore, but GHCRTS is also ignored. -rtsopts does not
1309 affect -with-rtsopts behavior; flags passed via -with-rtsopts
1310 are used regardless of -rtsopts.
1311 -shared
1313 Generate a shared library (as opposed to an executable)
1314 -split-sections
1316 Split sections for link-time dead-code stripping
1317 -static
1319 Use static Haskell libraries
1320 -staticlib
1322 Generate a standalone static library (as opposed to an exe‐
1323 cutable). This is useful when cross compiling. The library to‐
1324 gether with all its dependencies ends up in in a single static
1325 library that can be linked against.
1326 -threaded
1328 Use the threaded runtime
1329 -with-rtsopts=⟨opts⟩
1331 Set the default RTS options to ⟨opts⟩.
1332 Miscellaneous options
1334 -fexternal-interpreter
1335 Run interpreted code in a separate process
1336 -fglasgow-exts
1338 Deprecated. Enable most language extensions; see Language op‐
1339 tions for exactly which ones.
1340 -ghcversion-file ⟨path to ghcversion.h⟩
1342 (GHC as a C compiler only) Use this ghcversion.h file
1343 -H ⟨size⟩
1345 Set the minimum size of the heap to ⟨size⟩
1346 -j[⟨n⟩]
1348 When compiling with --make, compile ⟨n⟩ modules in parallel.
1349 Modes of operation
1351 --frontend ⟨module⟩
1352 run GHC with the given frontend plugin; see Frontend plugins for
1353 details.
1354 --help Display help
1356 --info display information about the compiler
1358 --interactive
1360 Interactive mode - normally used by just running ghci; see Using
1361 GHCi for details.
1362 --make Build a multi-module Haskell program, automatically figuring out
1364 dependencies. Likely to be much easier, and faster, than using
1365 make; see Using ghc --make for details.
1366 --mk-dll
1368 DLL-creation mode (Windows only)
1369 --numeric-version
1371 display GHC version (numeric only)
1372 --print-libdir
1374 display GHC library directory
1375 --show-iface ⟨file⟩
1377 display the contents of an interface file.
1378 --show-options
1380 display the supported command line options
1381 --supported-extensions
1383 display the supported language extensions
1384 --version
1386 display GHC version
1387 -e ⟨expr⟩
1389 Evaluate expr; see Expression evaluation mode for details.
1390 -M generate dependency information suitable for use in a Makefile;
1392 see Dependency generation for details.
1393 Individual optimizations
1395 -fasm-shortcutting
1396 Enable shortcutting on assembly. Implied by -O2.
1397 -fbinary-blob-threshold=⟨n⟩
1399 default: 500K. Tweak assembly generator for binary blobs.
1400 -fblock-layout-cfg
1402 Use the new cfg based block layout algorithm.
1403 -fblock-layout-weightless
1405 Ignore cfg weights for code layout.
1406 -fblock-layout-weights
1408 Sets edge weights used by the new code layout algorithm.
1409 -fcall-arity
1411 Enable call-arity optimisation. Implied by -O.
1412 -fcase-folding
1414 Enable constant folding in case expressions. Implied by -O.
1415 -fcase-merge
1417 Enable case-merging. Implied by -O.
1418 -fcmm-elim-common-blocks
1420 Enable Cmm common block elimination. Implied by -O.
1421 -fcmm-sink
1423 Enable Cmm sinking. Implied by -O.
1424 -fcpr-anal
1426 Turn on CPR analysis in the demand analyser. Implied by -O.
1427 -fcross-module-specialise
1429 Turn on specialisation of overloaded functions imported from
1430 other modules.
1431 -fcse Enable common sub-expression elimination. Implied by -O.
1433 -fdicts-cheap
1435 Make dictionary-valued expressions seem cheap to the optimiser.
1436 -fdicts-strict
1438 Make dictionaries strict
1439 -fdmd-tx-dict-sel
1441 Use a special demand transformer for dictionary selectors. Al‐
1442 ways enabled by default.
1443 -fdo-eta-reduction
1445 Enable eta-reduction. Implied by -O.
1446 -fdo-lambda-eta-expansion
1448 Enable lambda eta-expansion. Always enabled by default.
1449 -feager-blackholing
1451 Turn on eager blackholing
1452 -fenable-rewrite-rules
1454 Switch on all rewrite rules (including rules generated by auto‐
1455 matic specialisation of overloaded functions). Implied by -O.
1456 -fexcess-precision
1458 Enable excess intermediate precision
1459 -fexitification
1461 Enables exitification optimisation. Implied by -O.
1462 -fexpose-all-unfoldings
1464 Expose all unfoldings, even for very large or recursive func‐
1465 tions.
1466 -ffloat-in
1468 Turn on the float-in transformation. Implied by -O.
1469 -ffull-laziness
1471 Turn on full laziness (floating bindings outwards). Implied by
1472 -O.
1473 -ffun-to-thunk
1475 Allow worker-wrapper to convert a function closure into a thunk
1476 if the function does not use any of its arguments. Off by de‐
1477 fault.
1478 -fignore-asserts
1480 Ignore assertions in the source. Implied by -O.
1481 -fignore-interface-pragmas
1483 Ignore pragmas in interface files. Implied by -O0 only.
1484 -flate-dmd-anal
1486 Run demand analysis again, at the end of the simplification
1487 pipeline
1488 -flate-specialise
1490 Run a late specialisation pass
1491 -fliberate-case
1493 Turn on the liberate-case transformation. Implied by -O2.
1494 -fliberate-case-threshold=⟨n⟩
1496 default: 2000. Set the size threshold for the liberate-case
1497 transformation to ⟨n⟩
1498 -fllvm-pass-vectors-in-regs
1500 Pass vector value in vector registers for function calls
1501 -floopification
1503 Turn saturated self-recursive tail-calls into local jumps in the
1504 generated assembly. Implied by -O.
1505 -fmax-inline-alloc-size=⟨n⟩
1507 default: 128. Set the maximum size of inline array allocations
1508 to ⟨n⟩ bytes (default: 128).
1509 -fmax-inline-memcpy-insns=⟨n⟩
1511 default: 32. Inline memcpy calls if they would generate no more
1512 than ⟨n⟩ pseudo instructions.
1513 -fmax-inline-memset-insns=⟨n⟩
1515 default: 32. Inline memset calls if they would generate no more
1516 than ⟨n⟩ pseudo instructions
1517 -fmax-simplifier-iterations=⟨n⟩
1519 default: 4. Set the max iterations for the simplifier.
1520 -fmax-uncovered-patterns=⟨n⟩
1522 default: 4. Set the maximum number of patterns to display in
1523 warnings about non-exhaustive ones.
1524 -fmax-worker-args=⟨n⟩
1526 default: 10. If a worker has that many arguments, none will be
1527 unpacked anymore.
1528 -fno-opt-coercion
1530 Turn off the coercion optimiser
1531 -fno-pre-inlining
1533 Turn off pre-inlining
1534 -fno-state-hack
1536 Turn off the state hackwhereby any lambda with a real-world
1537 state token as argument is considered to be single-entry. Hence
1538 OK to inline things inside it.
1539 -fomit-interface-pragmas
1541 Don't generate interface pragmas. Implied by -O0 only.
1542 -fomit-yields
1544 Omit heap checks when no allocation is being performed.
1545 -foptimal-applicative-do
1547 Use a slower but better algorithm for ApplicativeDo
1548 -fpedantic-bottoms
1550 Make GHC be more precise about its treatment of bottom (but see
1551 also -fno-state-hack). In particular, GHC will not eta-expand
1552 through a case expression.
1553 -fregs-graph
1555 Use the graph colouring register allocator for register alloca‐
1556 tion in the native code generator. Implied by -O2.
1557 -fregs-iterative
1559 Use the iterative coalescing graph colouring register allocator
1560 in the native code generator.
1561 -fsimpl-tick-factor=⟨n⟩
1563 default: 100. Set the percentage factor for simplifier ticks.
1564 -fsimplifier-phases=⟨n⟩
1566 default: 2. Set the number of phases for the simplifier. Ig‐
1567 nored with -O0.
1568 -fsolve-constant-dicts
1570 When solving constraints, try to eagerly solve super classes us‐
1571 ing available dictionaries.
1572 -fspec-constr
1574 Turn on the SpecConstr transformation. Implied by -O2.
1575 -fspec-constr-count=⟨n⟩
1577 default: 3.* Set to ⟨n⟩ the maximum number of specialisations
1578 that will be created for any one function by the SpecConstr
1579 transformation.
1580 -fspec-constr-keen
1582 Specialize a call with an explicit constructor argument, even if
1583 the argument is not scrutinised in the body of the function
1584 -fspec-constr-threshold=⟨n⟩
1586 default: 2000. Set the size threshold for the SpecConstr trans‐
1587 formation to ⟨n⟩.
1588 -fspecialise
1590 Turn on specialisation of overloaded functions. Implied by -O.
1591 -fspecialise-aggressively
1593 Turn on specialisation of overloaded functions regardless of
1594 size, if unfolding is available
1595 -fstatic-argument-transformation
1597 Turn on the static argument transformation.
1598 -fstg-cse
1600 Enable common sub-expression elimination on the STG intermediate
1601 language
1602 -fstg-lift-lams
1604 Enable late lambda lifting on the STG intermediate language. Im‐
1605 plied by -O2.
1606 -fstg-lift-lams-known
1608 Allow turning known into unknown calls while performing late
1609 lambda lifting.
1610 -fstg-lift-lams-non-rec-args
1612 Create top-level non-recursive functions with at most <n> param‐
1613 eters while performing late lambda lifting.
1614 -fstg-lift-lams-rec-args
1616 Create top-level recursive functions with at most <n> parameters
1617 while performing late lambda lifting.
1618 -fstrictness
1620 Turn on strictness analysis. Implied by -O. Implies
1621 -fworker-wrapper
1622 -fstrictness-before=⟨n⟩
1624 Run an additional strictness analysis before simplifier phase
1625 ⟨n⟩
1626 -funbox-small-strict-fields
1628 Flatten strict constructor fields with a pointer-sized represen‐
1629 tation. Implied by -O.
1630 -funbox-strict-fields
1632 Flatten strict constructor fields
1633 -funfolding-creation-threshold=⟨n⟩
1635 default: 750. Tweak unfolding settings.
1636 -funfolding-dict-discount=⟨n⟩
1638 default: 30. Tweak unfolding settings.
1639 -funfolding-fun-discount=⟨n⟩
1641 default: 60. Tweak unfolding settings.
1642 -funfolding-keeness-factor=⟨n⟩
1644 default: 1.5. Tweak unfolding settings.
1645 -funfolding-use-threshold=⟨n⟩
1647 default: 60. Tweak unfolding settings.
1648 -fworker-wrapper
1650 Enable the worker-wrapper transformation.
1651 Optimization levels
1653 -O Enable level 1 optimisations
1654 -O0 Disable optimisations (default)
1656 -O2 Enable level 2 optimisations
1658 -O⟨n⟩ Any -On where n > 2 is the same as -O2.
1660 Package options
1662 -clear-package-db
1663 Clear the package db stack.
1664 -distrust ⟨pkg⟩
1666 Expose package ⟨pkg⟩ and set it to be distrusted. See Safe
1667 Haskell.
1668 -distrust-all-packages
1670 Distrust all packages by default. See Safe Haskell.
1671 -fpackage-trust
1673 Enable Safe Haskell trusted package requirement for trustworthy
1674 modules.
1675 -global-package-db
1677 Add the global package db to the stack.
1678 -hide-all-packages
1680 Hide all packages by default
1681 -hide-package ⟨pkg⟩
1683 Hide package ⟨pkg⟩
1684 -ignore-package ⟨pkg⟩
1686 Ignore package ⟨pkg⟩
1687 -no-auto-link-packages
1689 Don't automatically link in the base and rts packages.
1690 -no-global-package-db
1692 Remove the global package db from the stack.
1693 -no-user-package-db
1695 Remove the user's package db from the stack.
1696 -package ⟨pkg⟩
1698 Expose package ⟨pkg⟩
1699 -package-db ⟨file⟩
1701 Add ⟨file⟩ to the package db stack.
1702 -package-env ⟨file⟩|⟨name⟩
1704 Use the specified package environment.
1705 -package-id ⟨unit-id⟩
1707 Expose package by id ⟨unit-id⟩
1708 -this-unit-id ⟨unit-id⟩
1710 Compile to be part of unit (i.e. package) ⟨unit-id⟩
1711 -trust ⟨pkg⟩
1713 Expose package ⟨pkg⟩ and set it to be trusted. See Safe Haskell.
1714 -user-package-db
1716 Add the user's package db to the stack.
1717 Phases of compilation
1719 -C Stop after generating C (.hc file)
1720 -c Stop after generating object (.o) file
1722 -E Stop after preprocessing (.hspp file)
1724 -F Enable the use of a pre-processor (set with -pgmF ⟨cmd⟩)
1726 -S Stop after generating assembly (.s file)
1728 -x ⟨suffix⟩
1730 Override default behaviour for source files
1731 Overriding external programs
1733 -pgma ⟨cmd⟩
1734 Use ⟨cmd⟩ as the assembler
1735 -pgmc ⟨cmd⟩
1737 Use ⟨cmd⟩ as the C compiler
1738 -pgmdll ⟨cmd⟩
1740 Use ⟨cmd⟩ as the DLL generator
1741 -pgmF ⟨cmd⟩
1743 Use ⟨cmd⟩ as the pre-processor (with -F only)
1744 -pgmi ⟨cmd⟩
1746 Use ⟨cmd⟩ as the external interpreter command.
1747 -pgminstall_name_tool ⟨cmd⟩
1749 Use ⟨cmd⟩ as the program to inject runpath into mach-o dylibs on
1750 macOS
1751 -pgmL ⟨cmd⟩
1753 Use ⟨cmd⟩ as the literate pre-processor
1754 -pgml ⟨cmd⟩
1756 Use ⟨cmd⟩ as the linker
1757 -pgmlc ⟨cmd⟩
1759 Use ⟨cmd⟩ as the LLVM compiler
1760 -pgmlibtool ⟨cmd⟩
1762 Use ⟨cmd⟩ as the command for libtool (with -staticlib only).
1763 -pgmlm ⟨cmd⟩
1765 Use ⟨cmd⟩ as the linker when merging object files
1766 -pgmlo ⟨cmd⟩
1768 Use ⟨cmd⟩ as the LLVM optimiser
1769 -pgmotool ⟨cmd⟩
1771 Use ⟨cmd⟩ as the program to inspect mach-o dylibs on macOS
1772 -pgmP ⟨cmd⟩
1774 Use ⟨cmd⟩ as the C pre-processor (with -cpp only)
1775 -pgms ⟨cmd⟩
1777 Use ⟨cmd⟩ as the splitter
1778 -pgmwindres ⟨cmd⟩
1780 Use ⟨cmd⟩ as the program for embedding manifests on Windows.
1781 Phase-specific options
1783 -opta ⟨option⟩
1784 pass ⟨option⟩ to the assembler
1785 -optc ⟨option⟩
1787 pass ⟨option⟩ to the C compiler
1788 -optcxx ⟨option⟩
1790 pass ⟨option⟩ to the C++ compiler
1791 -optdll ⟨option⟩
1793 pass ⟨option⟩ to the DLL generator
1794 -optF ⟨option⟩
1796 pass ⟨option⟩ to the custom pre-processor
1797 -opti ⟨option⟩
1799 pass ⟨option⟩ to the interpreter sub-process.
1800 -optL ⟨option⟩
1802 pass ⟨option⟩ to the literate pre-processor
1803 -optl ⟨option⟩
1805 pass ⟨option⟩ to the linker
1806 -optlc ⟨option⟩
1808 pass ⟨option⟩ to the LLVM compiler
1809 -optlm ⟨option⟩
1811 pass ⟨option⟩ to the linker when merging object files.
1812 -optlo ⟨option⟩
1814 pass ⟨option⟩ to the LLVM optimiser
1815 -optP ⟨option⟩
1817 pass ⟨option⟩ to cpp (with -cpp only)
1818 -optwindres ⟨option⟩
1820 pass ⟨option⟩ to windres.
1821 -pgmc-supports-no-pie
1823 Indicate that the C compiler supports -no-pie
1824 Platform-specific options
1826 -mbmi2 (x86 only) Use BMI2 for bit manipulation operations
1827 -msse2 (x86 only) Use SSE2 for floating-point operations
1829 -msse4.2
1831 (x86 only) Use SSE4.2 for floating-point operations
1832 Compiler plugins
1834 -fclear-plugins
1835 Clear the list of active plugins
1836 -fplugin-opt=⟨module⟩:⟨args⟩
1838 Give arguments to a plugin module; module must be specified with
1839 -fplugin=⟨module⟩
1840 -fplugin-trustworthy
1842 Trust the used plugins and no longer mark the compiled module as
1843 unsafe
1844 -fplugin=⟨module⟩
1846 Load a plugin exported by a given module
1847 -hide-all-plugin-packages
1849 Hide all packages for plugins by default
1850 -plugin-package ⟨pkg⟩
1852 Expose ⟨pkg⟩ for plugins
1853 -plugin-package-id ⟨pkg-id⟩
1855 Expose ⟨pkg-id⟩ for plugins
1856 Profiling
1858 -fno-prof-auto
1859 Disables any previous -fprof-auto, -fprof-auto-top, or
1860 -fprof-auto-exported options.
1861 -fno-prof-cafs
1863 Disables any previous -fprof-cafs option.
1864 -fno-prof-count-entries
1866 Do not collect entry counts
1867 -fprof-auto
1869 Auto-add SCC\ s to all bindings not marked INLINE
1870 -fprof-auto-calls
1872 Auto-add SCC\ s to all call sites
1873 -fprof-auto-exported
1875 Auto-add SCC\ s to all exported bindings not marked INLINE
1876 -fprof-auto-top
1878 Auto-add SCC\ s to all top-level bindings not marked INLINE
1879 -fprof-cafs
1881 Auto-add SCC\ s to all CAFs
1882 -prof Turn on profiling
1884 -ticky Turn on ticky-ticky profiling
1886 Program coverage
1888 -fhpc Turn on Haskell program coverage instrumentation
1889 Recompilation checking
1891 -fforce-recomp
1892 Turn off recompilation checking. This is implied by any -ddump-X
1893 option when compiling a single file (i.e. when using -c).
1894 -fignore-hpc-changes
1896 Do not recompile modules just to match changes to HPC flags.
1897 This is especially useful for avoiding recompilation when using
1898 GHCi, and is enabled by default for GHCi.
1899 -fignore-optim-changes
1901 Do not recompile modules just to match changes to optimisation
1902 flags. This is especially useful for avoiding recompilation when
1903 using GHCi, and is enabled by default for GHCi.
1904 Redirecting output
1906 --exclude-module=⟨file⟩
1907 Regard ⟨file⟩ as "stable"; i.e., exclude it from having depen‐
1908 dencies on it.
1909 -ddump-mod-cycles
1911 Dump module cycles
1912 -dep-makefile ⟨file⟩
1914 Use ⟨file⟩ as the makefile
1915 -dep-suffix ⟨suffix⟩
1917 Make dependencies that declare that files with suffix
1918 .⟨suf⟩⟨osuf⟩ depend on interface files with suffix .⟨suf⟩hi
1919 -dumpdir ⟨dir⟩
1921 redirect dump files
1922 -hcsuf ⟨suffix⟩
1924 set the suffix to use for intermediate C files
1925 -hidir ⟨dir⟩
1927 set directory for interface files
1928 -hiedir ⟨dir⟩
1930 set directory for extended interface files
1931 -hiesuf ⟨suffix⟩
1933 set the suffix to use for extended interface files
1934 -hisuf ⟨suffix⟩
1936 set the suffix to use for interface files
1937 -include-cpp-deps
1939 Include preprocessor dependencies
1940 -include-pkg-deps
1942 Regard modules imported from packages as unstable
1943 -o ⟨file⟩
1945 set output filename
1946 -odir ⟨dir⟩
1948 set directory for object files
1949 -ohi ⟨file⟩
1951 set the filename in which to put the interface
1952 -osuf ⟨suffix⟩
1954 set the output file suffix
1955 -outputdir ⟨dir⟩
1957 set output directory
1958 -stubdir ⟨dir⟩
1960 redirect FFI stub files
1961 Temporary files
1963 -tmpdir ⟨dir⟩
1964 set the directory for temporary files
1965 Verbosity options
1967 -fabstract-refinement-hole-fits
1968 default: off. Toggles whether refinements where one or more of
1969 the holes are abstract are reported.
1970 -fdefer-diagnostics
1972 Defer and group diagnostic messages by severity
1973 -fdiagnostics-color=⟨always|auto|never⟩
1975 Use colors in error messages
1976 -fdiagnostics-show-caret
1978 Whether to show snippets of original source code
1979 -ferror-spans
1981 Output full span in error messages
1982 -fhide-source-paths
1984 hide module source and object paths
1985 -fkeep-going
1987 Continue compilation as far as possible on errors
1988 -fmax-refinement-hole-fits=⟨n⟩
1990 default: 6. Set the maximum number of refinement hole fits for
1991 typed holes to display in type error messages.
1992 -fmax-relevant-binds=⟨n⟩
1994 default: 6. Set the maximum number of bindings to display in
1995 type error messages.
1996 -fmax-valid-hole-fits=⟨n⟩
1998 default: 6. Set the maximum number of valid hole fits for typed
1999 holes to display in type error messages.
2000 -fno-show-valid-hole-fits
2002 Disables showing a list of valid hole fits for typed holes in
2003 type error messages.
2004 -fno-sort-valid-hole-fits
2006 Disables the sorting of the list of valid hole fits for typed
2007 holes in type error messages.
2008 -fprint-axiom-incomps
2010 Display equation incompatibilities in closed type families
2011 -fprint-equality-relations
2013 Distinguish between equality relations when printing
2014 -fprint-expanded-synonyms
2016 In type errors, also print type-synonym-expanded types.
2017 -fprint-explicit-coercions
2019 Print coercions in types
2020 -fprint-explicit-foralls
2022 Print explicit forall quantification in types. See also Explic‐
2023 itForAll
2024 -fprint-explicit-kinds
2026 Print explicit kind foralls and kind arguments in types. See
2027 also KindSignatures
2028 -fprint-explicit-runtime-reps
2030 Print RuntimeRep variables in types which are runtime-represen‐
2031 tation polymorphic.
2032 -fprint-potential-instances
2034 display all available instances in type error messages
2035 -fprint-typechecker-elaboration
2037 Print extra information from typechecker.
2038 -fprint-unicode-syntax
2040 Use unicode syntax when printing expressions, types and kinds.
2041 See also UnicodeSyntax
2042 -frefinement-level-hole-fits=⟨n⟩
2044 default: off. Sets the level of refinement of the refinement
2045 hole fits, where level n means that hole fits of up to n holes
2046 will be considered.
2047 -freverse-errors
2049 Output errors in reverse order
2050 -fshow-docs-of-hole-fits
2052 Toggles whether to show the documentation of the valid hole fits
2053 in the output.
2054 -fshow-hole-constraints
2056 Show constraints when reporting typed holes.
2057 -fshow-hole-matches-of-hole-fits
2059 Toggles whether to show the type of the additional holes in re‐
2060 finement hole fits.
2061 -fshow-provenance-of-hole-fits
2063 Toggles whether to show the provenance of the valid hole fits in
2064 the output.
2065 -fshow-type-app-of-hole-fits
2067 Toggles whether to show the type application of the valid hole
2068 fits in the output.
2069 -fshow-type-app-vars-of-hole-fits
2071 Toggles whether to show what type each quantified variable takes
2072 in a valid hole fit.
2073 -fshow-type-of-hole-fits
2075 Toggles whether to show the type of the valid hole fits in the
2076 output.
2077 -funclutter-valid-hole-fits
2079 Unclutter the list of valid hole fits by not showing provenance
2080 nor type applications of suggestions.
2081 -Rghc-timing
2083 Summarise timing stats for GHC (same as +RTS -tstderr).
2084 -v verbose mode (equivalent to -v3)
2086 -v⟨n⟩ set verbosity level
2088 Warnings
2090 -fdefer-out-of-scope-variables
2091 Convert variable out of scope variables errors into warnings.
2092 Implied by -fdefer-type-errors. See also
2093 -Wdeferred-out-of-scope-variables.
2094 -fdefer-type-errors
2096 Turn type errors into warnings, deferring the error until run‐
2097 time. Implies -fdefer-typed-holes and
2098 -fdefer-out-of-scope-variables. See also -Wdeferred-type-errors
2099 -fdefer-typed-holes
2101 Convert typed hole errors into warnings, deferring the error un‐
2102 til runtime. Implied by -fdefer-type-errors. See also
2103 -Wtyped-holes.
2104 -fenable-th-splice-warnings
2106 Generate warnings for Template Haskell splices
2107 -fhelpful-errors
2109 Make suggestions for mis-spelled names.
2110 -fmax-pmcheck-models=⟨n⟩
2112 soft limit on the number of parallel models the pattern match
2113 checker should check a pattern match clause against
2114 -fshow-warning-groups
2116 show which group an emitted warning belongs to.
2117 -fvia-C
2119 use the C code generator
2120 -W enable normal warnings
2122 -w disable all warnings
2124 -Wall enable almost all warnings (details in Warnings and san‐
2126 ity-checking)
2127 -Wall-missed-specialisations
2129 warn when specialisation of any overloaded function fails.
2130 -Wauto-orphans
2132 (deprecated) Does nothing
2133 -Wcompat
2135 enable future compatibility warnings (details in Warnings and
2136 sanity-checking)
2137 -Wcompat-unqualified-imports
2139 Report unqualified imports of core libraries which are expected
2140 to cause compatibility problems in future releases.
2141 -Wcpp-undef
2143 warn on uses of the #if directive on undefined identifiers
2144 -Wdefault
2146 enable default flags
2147 -Wdeferred-out-of-scope-variables
2149 Report warnings when variable out-of-scope errors are deferred
2150 until runtime. See -fdefer-out-of-scope-variables.
2151 -Wdeferred-type-errors
2153 Report warnings when deferred type errors are enabled. This op‐
2154 tion is enabled by default. See -fdefer-type-errors.
2155 -Wdeprecated-flags
2157 warn about uses of commandline flags that are deprecated
2158 -Wdeprecations
2160 warn about uses of functions & types that have warnings or dep‐
2161 recated pragmas. Alias for -Wwarnings-deprecations
2162 -Wderiving-defaults
2164 warn about default deriving when using both DeriveAnyClass and
2165 GeneralizedNewtypeDeriving
2166 -Wderiving-typeable
2168 warn when Typeable is derived
2169 -Wdodgy-exports
2171 warn about dodgy exports
2172 -Wdodgy-foreign-imports
2174 warn about dodgy foreign imports
2175 -Wdodgy-imports
2177 warn about dodgy imports
2178 -Wduplicate-constraints
2180 warn when a constraint appears duplicated in a type signature
2181 -Wduplicate-exports
2183 warn when an entity is exported multiple times
2184 -Wempty-enumerations
2186 warn about enumerations that are empty
2187 -Werror
2189 make warnings fatal
2190 -Weverything
2192 enable all warnings supported by GHC
2193 -Whi-shadowing
2195 (deprecated) warn when a .hi file in the current directory shad‐
2196 ows a library
2197 -Widentities
2199 warn about uses of Prelude numeric conversions that are probably
2200 the identity (and hence could be omitted)
2201 -Wimplicit-kind-vars
2203 (deprecated) warn when kind variables are implicitly quantified
2204 over.
2205 -Wimplicit-prelude
2207 warn when the Prelude is implicitly imported
2208 -Winaccessible-code
2210 warn about inaccessible code
2211 -Wincomplete-patterns
2213 warn when a pattern match could fail
2214 -Wincomplete-record-updates
2216 warn when a record update could fail
2217 -Wincomplete-uni-patterns
2219 warn when a pattern match in a lambda expression or pattern
2220 binding could fail
2221 -Winferred-safe-imports
2223 warn when an explicitly Safe Haskell module imports a Safe-In‐
2224 ferred one
2225 -Winline-rule-shadowing
2227 Warn if a rewrite RULE might fail to fire because the function
2228 might be inlined before the rule has a chance to fire. See How
2229 rules interact with INLINE/NOINLINE pragmas.
2230 -Wmissed-extra-shared-lib
2232 Warn when GHCi can't load a shared lib.
2233 -Wmissed-specialisations
2235 warn when specialisation of an imported, overloaded function
2236 fails.
2237 -Wmissing-deriving-strategies
2239 warn when a deriving clause is missing a deriving strategy
2240 -Wmissing-export-lists
2242 warn when a module declaration does not explicitly list all ex‐
2243 ports
2244 -Wmissing-exported-signatures
2246 warn about top-level functions without signatures, only if they
2247 are exported. takes precedence over -Wmissing-signatures
2248 -Wmissing-exported-sigs
2250 (deprecated) warn about top-level functions without signatures,
2251 only if they are exported. takes precedence over -Wmissing-sig‐
2252 natures
2253 -Wmissing-fields
2255 warn when fields of a record are uninitialised
2256 -Wmissing-home-modules
2258 warn when encountering a home module imported, but not listed on
2259 the command line. Useful for cabal to ensure GHC won't pick up
2260 modules, not listed neither in exposed-modules, nor in
2261 other-modules.
2262 -Wmissing-import-lists
2264 warn when an import declaration does not explicitly list all the
2265 names brought into scope
2266 -Wmissing-local-signatures
2268 warn about polymorphic local bindings without signatures
2269 -Wmissing-local-sigs
2271 (deprecated) warn about polymorphic local bindings without sig‐
2272 natures
2273 -Wmissing-methods
2275 warn when class methods are undefined
2276 -Wmissing-monadfail-instances
2278 (deprecated) Warn when a failable pattern is used in a do-block
2279 that does not have a MonadFail instance.
2280 -Wmissing-pattern-synonym-signatures
2282 warn when pattern synonyms do not have type signatures
2283 -Wmissing-safe-haskell-mode
2285 warn when the Safe Haskell mode is not explicitly specified.
2286 -Wmissing-signatures
2288 warn about top-level functions without signatures
2289 -Wmissing-space-after-bang
2291 (deprecated) Does nothing
2292 -Wmonomorphism-restriction
2294 warn when the Monomorphism Restriction is applied
2295 -Wname-shadowing
2297 warn when names are shadowed
2298 -Wno-compat
2300 Disables all warnings enabled by -Wcompat.
2301 -Wnoncanonical-monad-instances
2303 warn when Applicative or Monad instances have noncanonical defi‐
2304 nitions of return, pure, (>>), or (*>). See flag description in
2305 Warnings and sanity-checking for more details.
2306 -Wnoncanonical-monadfail-instances
2308 (deprecated) warn when Monad or MonadFail instances have non‐
2309 canonical definitions of fail. See flag description in Warnings
2310 and sanity-checking for more details.
2311 -Wnoncanonical-monoid-instances
2313 warn when Semigroup or Monoid instances have noncanonical defi‐
2314 nitions of (<>) or mappend. See flag description in Warnings
2315 and sanity-checking for more details.
2316 -Worphans
2318 warn when the module contains orphan instance declarations or
2319 rewrite rules
2320 -Woverflowed-literals
2322 warn about literals that will overflow their type
2323 -Woverlapping-patterns
2325 warn about overlapping patterns
2326 -Wpartial-fields
2328 warn when defining a partial record field.
2329 -Wpartial-type-signatures
2331 warn about holes in partial type signatures when PartialTypeSig‐
2332 natures is enabled. Not applicable when PartialTypeSignatures is
2333 not enabled, in which case errors are generated for such holes.
2334 -Wredundant-constraints
2336 Have the compiler warn about redundant constraints in type sig‐
2337 natures.
2338 -Wredundant-record-wildcards
2340 Warn about record wildcard matches when the wildcard binds no
2341 patterns.
2342 -Wsafe warn if the module being compiled is regarded to be safe.
2344 -Wsemigroup
2346 warn when a Monoid is not Semigroup, and on non- Semigroup defi‐
2347 nitions of (<>)?
2348 -Wsimplifiable-class-constraints
2350 Warn about class constraints in a type signature that can be
2351 simplified using a top-level instance declaration.
2352 -Wspace-after-bang
2354 warn for missing space before the second argument of an infix
2355 definition of (!) when BangPatterns are not enabled
2356 -Wstar-binder
2358 warn about binding the (*) type operator despite StarIsType
2359 -Wstar-is-type
2361 warn when * is used to mean Data.Kind.Type
2362 -Wtabs warn if there are tabs in the source file
2364 -Wtrustworthy-safe
2366 warn if the module being compiled is marked as Trustworthy but
2367 it could instead be marked as Safe, a more informative bound.
2368 -Wtype-defaults
2370 warn when defaulting happens
2371 -Wtyped-holes
2373 Report warnings when typed hole errors are deferred until run‐
2374 time. See -fdefer-typed-holes.
2375 -Wunbanged-strict-patterns
2377 warn on pattern bind of unlifted variable that is neither bare
2378 nor banged
2379 -Wunrecognised-pragmas
2381 warn about uses of pragmas that GHC doesn't recognise
2382 -Wunrecognised-warning-flags
2384 throw a warning when an unrecognised -W... flag is encountered
2385 on the command line.
2386 -Wunsafe
2388 warn if the module being compiled is regarded to be unsafe. See
2389 Safe Haskell
2390 -Wunsupported-calling-conventions
2392 warn about use of an unsupported calling convention
2393 -Wunsupported-llvm-version
2395 Warn when using -fllvm with an unsupported version of LLVM.
2396 -Wunticked-promoted-constructors
2398 warn if promoted constructors are not ticked
2399 -Wunused-binds
2401 warn about bindings that are unused. Alias for
2402 -Wunused-top-binds, -Wunused-local-binds and
2403 -Wunused-pattern-binds
2404 -Wunused-do-bind
2406 warn about do bindings that appear to throw away values of types
2407 other than ()
2408 -Wunused-foralls
2410 warn about type variables in user-written forall\s that are un‐
2411 used
2412 -Wunused-imports
2414 warn about unnecessary imports
2415 -Wunused-local-binds
2417 warn about local bindings that are unused
2418 -Wunused-matches
2420 warn about variables in patterns that aren't used
2421 -Wunused-packages
2423 warn when package is requested on command line, but was never
2424 loaded.
2425 -Wunused-pattern-binds
2427 warn about pattern match bindings that are unused
2428 -Wunused-record-wildcards
2430 Warn about record wildcard matches when none of the bound vari‐
2431 ables are used.
2432 -Wunused-top-binds
2434 warn about top-level bindings that are unused
2435 -Wunused-type-patterns
2437 warn about unused type variables which arise from patterns in in
2438 type family and data family instances
2439 -Wwarn make warnings non-fatal
2441 -Wwarnings-deprecations
2443 warn about uses of functions & types that have warnings or dep‐
2444 recated pragmas
2445 -Wwrong-do-bind
2447 warn about do bindings that appear to throw away monadic values
2448 that you should have bound instead
2449
2451 Copyright 2015. The University Court of the University of Glasgow. All
2452 rights reserved.
2453
2455 The GHC Team
2456
2458 2022, GHC Team
24598.10.7 Aug 06, 2022 GHC(1)