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 <https://down‐
16 loads.haskell.org/ghc/latest/docs/users_guide.pdf> and HTML
17 <https://downloads.haskell.org/ghc/latest/docs/html/>.
18 Each of GHC's command line options is classified as either static or
20 dynamic. A static flag may only be specified on the command line,
21 whereas a dynamic flag may also be given in an OPTIONS pragma in a
22 source file or set from the GHCi command-line with :set .
23 As a rule of thumb, all the language options are dynamic, as are the
25 warning options and the debugging options.
26 The rest are static, with the notable exceptions of -v, -cpp, -fasm,
28 -fvia-C, -fllvm, and -#include. The OPTIONS sections lists the status
29 of each flag.
30 Common suffixes of file names for Haskell are:
32 .hs Haskell source code; preprocess, compile
34 .lhs literate Haskell source; unlit, preprocess, compile
36 .hi Interface file; contains information about exported symbols
38 .hc intermediate C files
40 .⟨way⟩_o
42 object files for "way" ⟨way⟩; common ways are:
43 dyn dynamically-linked
45 p built with profiling
47 .⟨way⟩_hi
49 interface files for "way" ⟨way⟩; common ways are:
50
52 Code generation
53 -dynamic-too -fasm -fllvm -fbyte-code -fexternal-dynamic-refs
54 -fllvm -fasm -fno-code -fobject-code -fPIC -fPIE -fwrite-inter‐
55 face
56 Debugging the compiler
58 -dcmm-lint -dcore-lint -ddump-asm -ddump-asm-expanded
59 -ddump-asm-liveness -ddump-asm-native -ddump-asm-regalloc
60 -ddump-asm-regalloc-stages -ddump-asm-stats -ddump-bcos
61 -ddump-cfg-weights -ddump-cmm -ddump-cmm-caf -ddump-cmm-cbe
62 -ddump-cmm-cfg -ddump-cmm-cps -ddump-cmm-from-stg
63 -ddump-cmm-info -ddump-cmm-opt -ddump-cmm-proc
64 -ddump-cmm-procmap -ddump-cmm-raw -ddump-cmm-sink -ddump-cmm-sp
65 -ddump-cmm-split -ddump-cmm-switch -ddump-cmm-verbose
66 -ddump-cmm-verbose-by-proc -ddump-core-stats -ddump-cpr-signa‐
67 tures -ddump-cpranal -ddump-cse -ddump-deriv -ddump-ds
68 -ddump-ds-preopt -ddump-ec-trace -ddump-file-prefix=⟨str⟩
69 -ddump-foreign -ddump-hie -ddump-hpc -ddump-if-trace -ddump-in‐
70 linings -ddump-json -ddump-llvm -ddump-mod-map -ddump-occur-anal
71 -ddump-opt-cmm -ddump-parsed -ddump-parsed-ast -ddump-prep
72 -ddump-rn -ddump-rn-ast -ddump-rn-stats -ddump-rn-trace
73 -ddump-rtti -ddump-rule-firings -ddump-rule-rewrites
74 -ddump-rules -ddump-simpl -ddump-simpl-iterations
75 -ddump-simpl-stats -ddump-spec -ddump-splices -ddump-stg
76 -ddump-stg-final -ddump-stg-unarised -ddump-str-signatures
77 -ddump-stranal -ddump-tc -ddump-tc-ast -ddump-tc-trace
78 -ddump-ticked -ddump-timings -ddump-to-file -ddump-types
79 -ddump-verbose-inlinings -ddump-worker-wrapper -dfast‐
80 string-stats -dhex-word-literals -dinitial-unique=⟨s⟩ -din‐
81 line-check=⟨str⟩ -dlinear-core-lint -dno-debug-output -dde‐
82 bug-output -dno-typeable-binds -dppr-case-as-let -dppr-cols=⟨n⟩
83 -dppr-debug -dppr-user-length -drule-check=⟨str⟩ -dshow-passes
84 -dstg-lint -dsuppress-all -dsuppress-coercions -dsuppress-idinfo
85 -dsuppress-module-prefixes -dsuppress-stg-free-vars -dsup‐
86 press-ticks -dsuppress-timestamps -dsuppress-type-applications
87 -dsuppress-type-signatures -dsuppress-unfoldings -dsup‐
88 press-uniques -dsuppress-var-kinds -dth-dec-file -dunique-incre‐
89 ment=⟨i⟩ -dverbose-core2core -dverbose-stg2stg -falignment-sani‐
90 tisation -fcatch-bottoms -fllvm-fill-undef-with-garbage
91 -fproc-alignment -g -g⟨n⟩
92 C pre-processor
94 -cpp -D⟨symbol⟩[=⟨value⟩] -U⟨symbol⟩ -I⟨dir⟩ -U⟨symbol⟩
95 Finding imports
97 -i -i⟨dir⟩[:⟨dir⟩]*
98 Interactive mode
100 -fbreak-on-error -fno-break-on-error -fbreak-on-exception
101 -fno-break-on-exception -fghci-hist-size=⟨n⟩ -fghci-leak-check
102 -fno-ghci-leak-check -flocal-ghci-history -fno-local-ghci-his‐
103 tory -fno-it -fno-no-it -fprint-bind-result -fno-print-bind-re‐
104 sult -fprint-evld-with-show -fshow-loaded-modules -ghci-script
105 -ignore-dot-ghci -interactive-print ⟨name⟩
106 Interface files
108 --show-iface ⟨file⟩ -ddump-hi -ddump-hi-diffs -ddump-minimal-im‐
109 ports
110 Keeping intermediate files
112 -keep-hc-file -keep-hc-files -keep-hi-files -no-keep-hi-files
113 -keep-hscpp-file -keep-hscpp-files -keep-llvm-file
114 -keep-llvm-files -keep-o-files -no-keep-o-files -keep-s-file
115 -keep-s-files -keep-tmp-files
116 Language options
118 -XAllowAmbiguousTypes -XApplicativeDo -XArrows -XBangPatterns
119 -XBinaryLiterals -XBlockArguments -XCApiFFI -XConstrainedClass‐
120 Methods -XConstraintKinds -XCPP -XCUSKs -XDataKinds -XDatatype‐
121 Contexts -XDefaultSignatures -XDeriveAnyClass -XDeriveDataTy‐
122 peable -XDeriveFoldable -XDeriveFunctor -XDeriveGeneric -XDeriv‐
123 eLift -XDeriveTraversable -XDerivingStrategies -XDerivingVia
124 -XDisambiguateRecordFields -XDuplicateRecordFields -XEmptyCase
125 -XEmptyDataDecls -XEmptyDataDeriving -XExistentialQuantification
126 -XExplicitForAll -XExplicitNamespaces -XExtendedDefaultRules
127 -XFlexibleContexts -XFlexibleInstances -XForeignFunctionInter‐
128 face -XFunctionalDependencies -XGADTs -XGADTSyntax -XGener‐
129 alisedNewtypeDeriving -XGeneralizedNewtypeDeriving -XGHCForeign‐
130 ImportPrim -XHaskell2010 -XHaskell98 -XHexFloatLiterals -XIm‐
131 plicitParams -XImportQualifiedPost -XImpredicativeTypes -XInco‐
132 herentInstances -XInstanceSigs -XInterruptibleFFI -XKindSigna‐
133 tures -XLambdaCase -XLexicalNegation -XLiberalTypeSynonyms
134 -XLinearTypes -XMagicHash -XMonadComprehensions -XMonad‐
135 FailDesugaring -XMonoLocalBinds -XMultiParamTypeClasses -XMulti‐
136 WayIf -XNamedFieldPuns -XNamedWildCards -XNegativeLiterals
137 -XNoImplicitPrelude -XNoMonomorphismRestriction -XNonde‐
138 creasingIndentation -XNoPatternGuards -XNoTraditionalRecordSyn‐
139 tax -XNPlusKPatterns -XNullaryTypeClasses -XNumDecimals -XNumer‐
140 icUnderscores -XOverlappingInstances -XOverloadedLabels -XOver‐
141 loadedLists -XOverloadedStrings -XPackageImports -XParallelList‐
142 Comp -XPartialTypeSignatures -XPatternSynonyms -XPolyKinds
143 -XPostfixOperators -XQualifiedDo -XQuantifiedConstraints
144 -XQuasiQuotes -XRank2Types -XRankNTypes -XRebindableSyntax
145 -XRecordWildCards -XRecursiveDo -XRoleAnnotations -XSafe -XS‐
146 copedTypeVariables -XStandaloneDeriving -XStandaloneKindSigna‐
147 tures -XStarIsType -XStaticPointers -XStrict -XStrictData -XTem‐
148 plateHaskell -XTemplateHaskellQuotes -XTransformListComp
149 -XTrustworthy -XTupleSections -XTypeApplications -XTypeFamilies
150 -XTypeFamilyDependencies -XTypeInType -XTypeOperators -XTypeSyn‐
151 onymInstances -XUnboxedSums -XUnboxedTuples -XUndecidableIn‐
152 stances -XUndecidableSuperClasses -XUnicodeSyntax -XUnliftedFFI‐
153 Types -XUnliftedNewtypes -XUnsafe -XViewPatterns
154 Linking options
156 -c -debug -dylib-install-name ⟨path⟩ -dynamic -dynload -eventlog
157 -fkeep-cafs -flink-rts -fno-embed-manifest -fno-gen-manifest
158 -fno-shared-implib -framework ⟨name⟩ -framework-path ⟨dir⟩
159 -fuse-rpaths -fno-use-rpaths -fwhole-archive-hs-libs -L ⟨dir⟩ -l
160 ⟨lib⟩ -main-is ⟨thing⟩ -no-hs-main -no-rtsopts-suggestions
161 -package ⟨name⟩ -pie -rdynamic -rtsopts[=⟨none|some|all|ig‐
162 nore|ignoreAll⟩] -shared -split-sections -static -staticlib
163 -threaded -with-rtsopts=⟨opts⟩
164 Miscellaneous options
166 -fexternal-interpreter -fglasgow-exts -fno-glasgow-exts
167 -fno-safe-haskell -ghcversion-file ⟨path to ghcversion.h⟩ -H
168 ⟨size⟩ -j[⟨n⟩]
169 Modes of operation
171 --frontend ⟨module⟩ --help -? --info --interactive --make
172 --mk-dll --numeric-version --print-libdir --show-iface ⟨file⟩
173 --show-options --supported-extensions --supported-languages
174 --version -V -e ⟨expr⟩ -M
175 Individual optimizations
177 -fasm-shortcutting -fno-asm-shortcutting -fbinary-blob-thresh‐
178 old=⟨n⟩ -fblock-layout-cfg -fno-block-layout-cfg -fblock-lay‐
179 out-weightless -fno-block-layout-weightless -fblock-lay‐
180 out-weights -fcall-arity -fno-call-arity -fcase-folding
181 -fno-case-folding -fcase-merge -fno-case-merge -fcmm-elim-com‐
182 mon-blocks -fno-cmm-elim-common-blocks -fcmm-sink -fno-cmm-sink
183 -fcmm-static-pred -fno-cmm-static-pred -fcpr-anal -fno-cpr-anal
184 -fcross-module-specialise -fno-cross-module-specialise -fcse
185 -fno-cse -fdicts-cheap -fno-dicts-cheap -fdicts-strict
186 -fno-dicts-strict -fdmd-tx-dict-sel -fno-dmd-tx-dict-sel
187 -fdo-eta-reduction -fno-do-eta-reduction -fdo-lambda-eta-expan‐
188 sion -fno-do-lambda-eta-expansion -feager-blackholing -fen‐
189 able-rewrite-rules -fno-enable-rewrite-rules -fexcess-precision
190 -fno-excess-precision -fexitification -fno-exitification -fex‐
191 pose-all-unfoldings -fno-expose-all-unfoldings -ffloat-in
192 -fno-float-in -ffull-laziness -fno-full-laziness -ffun-to-thunk
193 -fno-fun-to-thunk -fignore-asserts -fno-ignore-asserts -fig‐
194 nore-interface-pragmas -fno-ignore-interface-pragmas
195 -flate-dmd-anal -fno-late-dmd-anal -flate-specialise
196 -fno-late-specialise -fliberate-case -fno-liberate-case -fliber‐
197 ate-case-threshold=⟨n⟩ -fno-liberate-case-threshold
198 -fllvm-pass-vectors-in-regs -fno-llvm-pass-vectors-in-regs
199 -floopification -fno-loopification -fmax-inline-alloc-size=⟨n⟩
200 -fmax-inline-memcpy-insns=⟨n⟩ -fmax-inline-memset-insns=⟨n⟩
201 -fmax-simplifier-iterations=⟨n⟩ -fmax-uncovered-patterns=⟨n⟩
202 -fmax-worker-args=⟨n⟩ -fno-opt-coercion -fno-pre-inlining
203 -fno-state-hack -fomit-interface-pragmas -fno-omit-inter‐
204 face-pragmas -fomit-yields -fno-omit-yields -foptimal-applica‐
205 tive-do -fno-optimal-applicative-do -fpedantic-bottoms
206 -fno-pedantic-bottoms -fregs-graph -fno-regs-graph -fregs-itera‐
207 tive -fno-regs-iterative -fsimpl-tick-factor=⟨n⟩ -fsimpli‐
208 fier-phases=⟨n⟩ -fsolve-constant-dicts -fno-solve-constant-dicts
209 -fspec-constr -fno-spec-constr -fspec-constr-count=⟨n⟩
210 -fno-spec-constr-count -fspec-constr-keen -fno-spec-constr-keen
211 -fspec-constr-threshold=⟨n⟩ -fno-spec-constr-threshold -fspe‐
212 cialise -fno-specialise -fspecialise-aggressively -fno-spe‐
213 cialise-aggressively -fstatic-argument-transformation
214 -fno-static-argument-transformation -fstg-cse -fno-stg-cse
215 -fstg-lift-lams -fno-stg-lift-lams -fstg-lift-lams-known
216 -fno-stg-lift-lams-known -fstg-lift-lams-non-rec-args
217 -fno-stg-lift-lams-non-rec-args-any -fstg-lift-lams-rec-args
218 -fno-stg-lift-lams-rec-args-any -fstrictness -fno-strictness
219 -fstrictness-before=⟨n⟩ -funbox-small-strict-fields -fno-un‐
220 box-small-strict-fields -funbox-strict-fields -fno-un‐
221 box-strict-fields -funfolding-creation-threshold=⟨n⟩ -funfold‐
222 ing-dict-discount=⟨n⟩ -funfolding-fun-discount=⟨n⟩ -funfold‐
223 ing-keeness-factor=⟨n⟩ -funfolding-use-threshold=⟨n⟩
224 -fworker-wrapper
225 Optimization levels
227 -O -O1 -O0 -O0 -O2 -O0 -O⟨n⟩ -O0
228 Package options
230 -clear-package-db -distrust ⟨pkg⟩ -distrust-all-packages -fpack‐
231 age-trust -global-package-db -hide-all-packages -hide-package
232 ⟨pkg⟩ -ignore-package ⟨pkg⟩ -no-auto-link-packages
233 -no-global-package-db -no-user-package-db -package ⟨pkg⟩ -pack‐
234 age-db ⟨file⟩ -package-env ⟨file⟩|⟨name⟩ -package-id ⟨unit-id⟩
235 -this-unit-id ⟨unit-id⟩ -trust ⟨pkg⟩ -user-package-db
236 Phases of compilation
238 -C -c -E -F -S -x ⟨suffix⟩
239 Overriding external programs
241 -pgma ⟨cmd⟩ -pgmc ⟨cmd⟩ -pgmdll ⟨cmd⟩ -pgmF ⟨cmd⟩ -pgmi ⟨cmd⟩
242 -pgminstall_name_tool ⟨cmd⟩ -pgmL ⟨cmd⟩ -pgml ⟨cmd⟩ -pgmlc ⟨cmd⟩
243 -pgmlibtool ⟨cmd⟩ -pgmlm ⟨cmd⟩ -pgmlo ⟨cmd⟩ -pgmotool ⟨cmd⟩
244 -pgmP ⟨cmd⟩ -pgms ⟨cmd⟩ -pgmwindres ⟨cmd⟩
245 Phase-specific options
247 -opta ⟨option⟩ -optc ⟨option⟩ -optcxx ⟨option⟩ -optdll ⟨option⟩
248 -optF ⟨option⟩ -opti ⟨option⟩ -optL ⟨option⟩ -optl ⟨option⟩
249 -optlc ⟨option⟩ -optlm ⟨option⟩ -optlo ⟨option⟩ -optP ⟨option⟩
250 -optwindres ⟨option⟩ -pgmc-supports-no-pie
251 Platform-specific options
253 -mbmi2 -msse2 -msse4.2
254 Compiler plugins
256 -fclear-plugins -fplugin-opt=⟨module⟩:⟨args⟩ -fplugin-trustwor‐
257 thy -fplugin=⟨module⟩ -hide-all-plugin-packages -plugin-package
258 ⟨pkg⟩ -plugin-package-id ⟨pkg-id⟩
259 Profiling
261 -fno-prof-auto -fprof-auto -fno-prof-cafs -fprof-cafs
262 -fno-prof-count-entries -fprof-count-entries -fprof-auto
263 -fno-prof-auto -fprof-auto-calls -fno-prof-auto-calls
264 -fprof-auto-exported -fno-prof-auto -fprof-auto-top
265 -fno-prof-auto -fprof-cafs -fno-prof-cafs -prof -ticky
266 Program coverage
268 -fhpc
269 Recompilation checking
271 -fforce-recomp -fno-force-recomp -fignore-hpc-changes -fno-ig‐
272 nore-hpc-changes -fignore-optim-changes -fno-ignore-op‐
273 tim-changes
274 Redirecting output
276 --exclude-module=⟨file⟩ -ddump-mod-cycles -dep-makefile ⟨file⟩
277 -dep-suffix ⟨suffix⟩ -dumpdir ⟨dir⟩ -hcsuf ⟨suffix⟩ -hidir ⟨dir⟩
278 -hiedir ⟨dir⟩ -hiesuf ⟨suffix⟩ -hisuf ⟨suffix⟩ -include-cpp-deps
279 -include-pkg-deps -o ⟨file⟩ -odir ⟨dir⟩ -ohi ⟨file⟩ -osuf ⟨suf‐
280 fix⟩ -outputdir ⟨dir⟩ -stubdir ⟨dir⟩
281 Temporary files
283 -tmpdir ⟨dir⟩
284 Verbosity options
286 -fabstract-refinement-hole-fits -fno-abstract-refine‐
287 ment-hole-fits -fdefer-diagnostics -fdiagnostics-color=⟨al‐
288 ways|auto|never⟩ -fdiagnostics-show-caret -fno-diagnos‐
289 tics-show-caret -ferror-spans -fhide-source-paths -fkeep-going
290 -fmax-refinement-hole-fits=⟨n⟩ -fno-max-refinement-hole-fits
291 -fmax-relevant-binds=⟨n⟩ -fno-max-relevant-binds
292 -fmax-valid-hole-fits=⟨n⟩ -fno-max-valid-hole-fits
293 -fno-show-valid-hole-fits -fno-sort-valid-hole-fits
294 -fsort-valid-hole-fits -fprint-axiom-incomps -fno-print-ax‐
295 iom-incomps -fprint-equality-relations -fno-print-equality-rela‐
296 tions -fprint-expanded-synonyms -fno-print-expanded-synonyms
297 -fprint-explicit-coercions -fno-print-explicit-coercions
298 -fprint-explicit-foralls -fno-print-explicit-foralls -fprint-ex‐
299 plicit-kinds -fno-print-explicit-kinds -fprint-explicit-run‐
300 time-reps -fno-print-explicit-runtime-reps -fprint-potential-in‐
301 stances -fno-print-potential-instances -fprint-typechecker-elab‐
302 oration -fno-print-typechecker-elaboration -fprint-unicode-syn‐
303 tax -fno-print-unicode-syntax -frefinement-level-hole-fits=⟨n⟩
304 -fno-refinement-level-hole-fits -freverse-errors -fno-re‐
305 verse-errors -fshow-docs-of-hole-fits
306 -fno-show-docs-of-hole-fits -fshow-hole-constraints
307 -fshow-hole-matches-of-hole-fits
308 -fno-show-hole-matches-of-hole-fits -fshow-prove‐
309 nance-of-hole-fits -fno-show-provenance-of-hole-fits
310 -fshow-type-app-of-hole-fits -fno-show-type-app-of-hole-fits
311 -fshow-type-app-vars-of-hole-fits
312 -fno-show-type-app-vars-of-hole-fits -fshow-type-of-hole-fits
313 -fno-type-of-hole-fits -fsort-by-size-hole-fits
314 -fno-sort-by-size-hole-fits -fsort-by-subsumption-hole-fits
315 -fno-sort-by-subsumption-hole-fits -funclutter-valid-hole-fits
316 -Rghc-timing -v -v⟨n⟩
317 Warnings
319 -fdefer-out-of-scope-variables -fno-defer-out-of-scope-variables
320 -fdefer-type-errors -fno-defer-type-errors -fdefer-typed-holes
321 -fno-defer-typed-holes -fenable-th-splice-warnings -fno-en‐
322 able-th-splices -fhelpful-errors -fno-helpful-errors -fmax-pm‐
323 check-models=⟨n⟩ -fshow-warning-groups -fno-show-warning-groups
324 -fvia-C -W -w -w -Wall -w -Wall-missed-specialisations
325 -Wno-all-missed-specialisations -Wauto-orphans -Wcompat
326 -Wno-compat -Wcompat-unqualified-imports -Wno-compat-unquali‐
327 fied-imports -Wcpp-undef -Wdefault -Wdeferred-out-of-scope-vari‐
328 ables -Wno-deferred-out-of-scope-variables -Wdeferred-type-er‐
329 rors -Wno-deferred-type-errors -Wdeprecated-flags -Wno-depre‐
330 cated-flags -Wdeprecations -Wno-deprecations -Wderiving-defaults
331 -Wno-deriving-defaults -Wderiving-typeable -Wno-deriving-ty‐
332 peable -Wdodgy-exports -Wno-dodgy-exports -Wdodgy-foreign-im‐
333 ports -Wno-dodgy-foreign-import -Wdodgy-imports -Wno-dodgy-im‐
334 ports -Wduplicate-constraints -Wno-duplicate-constraints -Wdu‐
335 plicate-exports -Wno-duplicate-exports -Wempty-enumerations
336 -Wno-empty-enumerations -Werror -Wwarn -Weverything -Whi-shadow‐
337 ing -Wno-hi-shadowing -Widentities -Wno-identities -Wim‐
338 plicit-kind-vars -Wno-implicit-kind-vars -Wimplicit-prelude
339 -Wno-implicit-prelude -Winaccessible-code -Wno-inaccessible-code
340 -Wincomplete-patterns -Wno-incomplete-patterns -Wincom‐
341 plete-record-updates -Wno-incomplete-record-updates -Wincom‐
342 plete-uni-patterns -Wno-incomplete-uni-patterns -Win‐
343 ferred-safe-imports -Wno-inferred-safe-imports -Win‐
344 line-rule-shadowing -Wno-inline-rule-shadowing -Winvalid-haddock
345 -Wmissed-extra-shared-lib -Wno-missed-extra-shared-lib
346 -Wmissed-specialisations -Wno-missed-specialisations -Wmiss‐
347 ing-deriving-strategies -Wno-missing-deriving-strategies -Wmiss‐
348 ing-export-lists -fnowarn-missing-export-lists -Wmissing-ex‐
349 ported-signatures -Wno-missing-exported-signatures -Wmissing-ex‐
350 ported-sigs -Wno-missing-exported-sigs -Wmissing-fields
351 -Wno-missing-fields -Wmissing-home-modules -Wno-miss‐
352 ing-home-modules -Wmissing-import-lists -fnowarn-missing-im‐
353 port-lists -Wmissing-local-signatures -Wno-missing-local-signa‐
354 tures -Wmissing-local-sigs -Wno-missing-local-sigs -Wmiss‐
355 ing-methods -Wno-missing-methods -Wmissing-monadfail-instances
356 -Wno-missing-monadfail-instances -Wmissing-pattern-synonym-sig‐
357 natures -Wno-missing-pattern-synonym-signatures -Wmiss‐
358 ing-safe-haskell-mode -Wno-missing-safe-haskell-mode -Wmiss‐
359 ing-signatures -Wno-missing-signatures -Wmissing-space-af‐
360 ter-bang -Wmonomorphism-restriction -Wno-monomorphism-restric‐
361 tion -Wname-shadowing -Wno-name-shadowing -Wno-compat -Wcompat
362 -Wnoncanonical-monad-instances -Wno-noncanonical-monad-instances
363 -Wnoncanonical-monadfail-instances -Wno-noncanonical-monad‐
364 fail-instances -Wnoncanonical-monoid-instances -Wno-noncanoni‐
365 cal-monoid-instances -Worphans -Wno-orphans -Woverflowed-liter‐
366 als -Wno-overflowed-literals -Woverlapping-patterns -Wno-over‐
367 lapping-patterns -Wpartial-fields -Wno-partial-fields -Wpar‐
368 tial-type-signatures -Wno-partial-type-signatures -Wredun‐
369 dant-constraints -Wno-redundant-constraints -Wredun‐
370 dant-record-wildcards -Wno-redundant-record-wildcards -Wsafe
371 -Wno-safe -Wsemigroup -Wno-semigroup -Wsimplifiable-class-con‐
372 straints -Wno-simplifiable-class-constraints -Wstar-binder
373 -Wno-star-binder -Wstar-is-type -Wno-star-is-type -Wtabs
374 -Wno-tabs -Wtrustworthy-safe -Wno-safe -Wtype-defaults
375 -Wno-type-defaults -Wtyped-holes -Wno-typed-holes -Wun‐
376 banged-strict-patterns -Wno-unbanged-strict-patterns -Wuni‐
377 code-bidirectional-format-characters -Wunrecognised-pragmas
378 -Wno-unrecognised-pragmas -Wunrecognised-warning-flags -Wno-un‐
379 recognised-warning-flags -Wunsafe -Wno-unsafe -Wunsup‐
380 ported-calling-conventions -Wno-unsupported-calling-conventions
381 -Wunsupported-llvm-version -Wno-monomorphism-restriction
382 -Wunticked-promoted-constructors -Wno-unticked-promoted-con‐
383 structors -Wunused-binds -Wno-unused-binds -Wunused-do-bind
384 -Wno-unused-do-bind -Wunused-foralls -Wno-unused-foralls
385 -Wunused-imports -Wno-unused-imports -Wunused-local-binds
386 -Wno-unused-local-binds -Wunused-matches -Wno-unused-matches
387 -Wunused-packages -Wno-unused-packages -Wunused-pattern-binds
388 -Wno-unused-pattern-binds -Wunused-record-wildcards -Wno-un‐
389 used-record-wildcards -Wunused-top-binds -Wno-unused-top-binds
390 -Wunused-type-patterns -Wno-unused-type-patterns -Wwarn -Werror
391 -Wwarnings-deprecations -Wno-warnings-deprecations
392 -Wwrong-do-bind -Wno-wrong-do-bind
393 Code generation
395 -dynamic-too
396 Build dynamic object files as well as static object files during
397 compilation
398 -fasm Use the native code generator
400 -fbyte-code
402 Generate byte-code
403 -fexternal-dynamic-refs
405 Generate code for linking against dynamic libraries
406 -fllvm Compile using the LLVM code generator
408 -fno-code
410 Omit code generation
411 -fobject-code
413 Generate object code
414 -fPIC Generate position-independent code (where available)
416 -fPIE Generate code for a position-independent executable (where
418 available)
419 -fwrite-interface
421 Always write interface files
422 Debugging the compiler
424 -dcmm-lint
425 C-\- pass sanity checking
426 -dcore-lint
428 Turn on internal sanity checking
429 -ddump-asm
431 Dump final assembly
432 -ddump-asm-expanded
434 Dump the result of the synthetic instruction expansion pass.
435 -ddump-asm-liveness
437 Dump assembly augmented with register liveness
438 -ddump-asm-native
440 Dump initial assembly
441 -ddump-asm-regalloc
443 Dump the result of register allocation
444 -ddump-asm-regalloc-stages
446 Dump the build/spill stages of the -fregs-graph register alloca‐
447 tor.
448 -ddump-asm-stats
450 Dump statistics from the register allocator.
451 -ddump-bcos
453 Dump interpreter byte code
454 -ddump-cfg-weights
456 Dump the assumed weights of the CFG.
457 -ddump-cmm
459 Dump the final C-\- output
460 -ddump-cmm-caf
462 Dump the results of the C-\- CAF analysis pass.
463 -ddump-cmm-cbe
465 Dump the results of common block elimination
466 -ddump-cmm-cfg
468 Dump the results of the C-\- control flow optimisation pass.
469 -ddump-cmm-cps
471 Dump the results of the CPS pass
472 -ddump-cmm-from-stg
474 Dump STG-to-C-\- output
475 -ddump-cmm-info
477 Dump the results of the C-\- info table augmentation pass.
478 -ddump-cmm-opt
480 Dump the results of C-\- to C-\- optimising passes
481 -ddump-cmm-proc
483 Dump the results of proc-point analysis
484 -ddump-cmm-procmap
486 Dump the results of the C-\- proc-point map pass.
487 -ddump-cmm-raw
489 Dump raw C-\-
490 -ddump-cmm-sink
492 Dump the results of the C-\- sinking pass.
493 -ddump-cmm-sp
495 Dump the results of the C-\- stack layout pass.
496 -ddump-cmm-split
498 Dump the results of the C-\- proc-point splitting pass.
499 -ddump-cmm-switch
501 Dump the results of switch lowering passes
502 -ddump-cmm-verbose
504 Write output from main C-\- pipeline passes to files
505 -ddump-cmm-verbose-by-proc
507 Show output from main C-\- pipeline passes (grouped by proc)
508 -ddump-core-stats
510 Print a one-line summary of the size of the Core program at the
511 end of the optimisation pipeline
512 -ddump-cpr-signatures
514 Dump CPR signatures
515 -ddump-cpranal
517 Dump CPR analysis output
518 -ddump-cse
520 Dump CSE output
521 -ddump-deriv
523 Dump deriving output
524 -ddump-ds
526 Dump desugarer output.
527 -ddump-ec-trace
529 Trace exhaustiveness checker
530 -ddump-file-prefix=⟨str⟩
532 Set the prefix of the filenames used for debugging output.
533 -ddump-foreign
535 Dump foreign export stubs
536 -ddump-hie
538 Dump the hie file syntax tree
539 -ddump-hpc
541 An alias for -ddump-ticked.
542 -ddump-if-trace
544 Trace interface files
545 -ddump-inlinings
547 Dump inlinings performed by the simplifier.
548 -ddump-json
550 Dump error messages as JSON documents
551 -ddump-llvm
553 Dump LLVM intermediate code.
554 -ddump-mod-map
556 Dump the state of the module mapping database.
557 -ddump-occur-anal
559 Dump occurrence analysis output
560 -ddump-opt-cmm
562 Dump the results of C-\- to C-\- optimising passes
563 -ddump-parsed
565 Dump parse tree
566 -ddump-parsed-ast
568 Dump parser output as a syntax tree
569 -ddump-prep
571 Dump prepared core
572 -ddump-rn
574 Dump renamer output
575 -ddump-rn-ast
577 Dump renamer output as a syntax tree
578 -ddump-rn-stats
580 Renamer stats
581 -ddump-rn-trace
583 Trace renamer
584 -ddump-rtti
586 Trace runtime type inference
587 -ddump-rule-firings
589 Dump rule firing info
590 -ddump-rule-rewrites
592 Dump detailed rule firing info
593 -ddump-rules
595 Dump rewrite rules
596 -ddump-simpl
598 Dump final simplifier output
599 -ddump-simpl-iterations
601 Dump output from each simplifier iteration
602 -ddump-simpl-stats
604 Dump simplifier stats
605 -ddump-spec
607 Dump specialiser output
608 -ddump-splices
610 Dump TH spliced expressions, and what they evaluate to
611 -ddump-stg
613 Show CoreToStg output
614 -ddump-stg-final
616 Show output of last STG pass.
617 -ddump-stg-unarised
619 Show unarised STG
620 -ddump-str-signatures
622 Dump strictness signatures
623 -ddump-stranal
625 Dump strictness analyser output
626 -ddump-tc
628 Dump typechecker output
629 -ddump-tc-ast
631 Dump typechecker output as a syntax tree
632 -ddump-tc-trace
634 Trace typechecker
635 -ddump-ticked
637 Dump the code instrumented by HPC (Observing Code Coverage).
638 -ddump-timings
640 Dump per-pass timing and allocation statistics
641 -ddump-to-file
643 Dump to files instead of stdout
644 -ddump-types
646 Dump type signatures
647 -ddump-verbose-inlinings
649 Dump all considered inlinings
650 -ddump-worker-wrapper
652 Dump worker-wrapper output
653 -dfaststring-stats
655 Show statistics for fast string usage when finished
656 -dhex-word-literals
658 Print values of type Word# in hexadecimal.
659 -dinitial-unique=⟨s⟩
661 Start UniqSupply allocation from ⟨s⟩.
662 -dinline-check=⟨str⟩
664 Dump information about inlining decisions
665 -dlinear-core-lint
667 Turn on internal sanity checking
668 -dno-debug-output
670 Suppress unsolicited debugging output
671 -dno-typeable-binds
673 Don't generate bindings for Typeable methods
674 -dppr-case-as-let
676 Print single alternative case expressions as strict lets.
677 -dppr-cols=⟨n⟩
679 Set the width of debugging output. For example -dppr-cols200
680 -dppr-debug
682 Turn on debug printing (more verbose)
683 -dppr-user-length
685 Set the depth for printing expressions in error msgs
686 -drule-check=⟨str⟩
688 Dump information about potential rule application
689 -dshow-passes
691 Print out each pass name as it happens
692 -dstg-lint
694 STG pass sanity checking
695 -dsuppress-all
697 In dumps, suppress everything (except for uniques) that is sup‐
698 pressible.
699 -dsuppress-coercions
701 Suppress the printing of coercions in Core dumps to make them
702 shorter
703 -dsuppress-idinfo
705 Suppress extended information about identifiers where they are
706 bound
707 -dsuppress-module-prefixes
709 Suppress the printing of module qualification prefixes
710 -dsuppress-stg-free-vars
712 Suppress the printing of closure free variable lists in STG out‐
713 put
714 -dsuppress-ticks
716 Suppress "ticks" in the pretty-printer output.
717 -dsuppress-timestamps
719 Suppress timestamps in dumps
720 -dsuppress-type-applications
722 Suppress type applications
723 -dsuppress-type-signatures
725 Suppress type signatures
726 -dsuppress-unfoldings
728 Suppress the printing of the stable unfolding of a variable at
729 its binding site
730 -dsuppress-uniques
732 Suppress the printing of uniques in debug output (easier to use
733 diff)
734 -dsuppress-var-kinds
736 Suppress the printing of variable kinds
737 -dth-dec-file
739 Dump evaluated TH declarations into *.th.hs files
740 -dunique-increment=⟨i⟩
742 Set the increment for the generated Unique's to ⟨i⟩.
743 -dverbose-core2core
745 Show output from each core-to-core pass
746 -dverbose-stg2stg
748 Show output from each STG-to-STG pass
749 -falignment-sanitisation
751 Compile with alignment checks for all info table dereferences.
752 -fcatch-bottoms
754 Add a default error alternative to case expressions without a
755 default alternative.
756 -fllvm-fill-undef-with-garbage
758 Intruct LLVM to fill dead STG registers with garbage
759 -fproc-alignment
761 Align functions at given boundary.
762 -g Produce DWARF debug information in compiled object files. ⟨n⟩
764 can be 0, 1, or 2, with higher numbers producing richer output.
765 If ⟨n⟩ is omitted, level 2 is assumed.
766 C pre-processor
768 -cpp Run the C pre-processor on Haskell source files
769 -D⟨symbol⟩[=⟨value⟩]
771 Define a symbol in the C pre-processor
772 -I⟨dir⟩
774 Add ⟨dir⟩ to the directory search list for #include files
775 -U⟨symbol⟩
777 Undefine a symbol in the C pre-processor
778 Finding imports
780 -i Empty the import directory list
781 -i⟨dir⟩[:⟨dir⟩]*
783 add ⟨dir⟩, ⟨dir2⟩, etc. to import path
784 Interactive mode
786 -fbreak-on-error
787 Break on uncaught exceptions and errors
788 -fbreak-on-exception
790 Break on any exception thrown
791 -fghci-hist-size=⟨n⟩
793 Set the number of entries GHCi keeps for :history. See The GHCi
794 Debugger.
795 -fghci-leak-check
797 (Debugging only) check for space leaks when loading new modules
798 in GHCi.
799 -flocal-ghci-history
801 Use current directory for the GHCi command history file
802 .ghci-history.
803 -fno-it
805 No longer set the special variable it.
806 -fprint-bind-result
808 Turn on printing of binding results in GHCi
809 -fprint-evld-with-show
811 Instruct :print to use Show instances where possible.
812 -fshow-loaded-modules
814 Show the names of modules that GHCi loaded after a :load com‐
815 mand.
816 -ghci-script
818 Read additional .ghci files
819 -ignore-dot-ghci
821 Disable reading of .ghci files
822 -interactive-print ⟨name⟩
824 Select the function to use for printing evaluated expressions in
825 GHCi
826 Interface files
828 --show-iface ⟨file⟩
829 See Modes of operation.
830 -ddump-hi
832 Dump the new interface to stdout
833 -ddump-hi-diffs
835 Show the differences vs. the old interface
836 -ddump-minimal-imports
838 Dump a minimal set of imports
839 Keeping intermediate files
841 -keep-hc-file
842 Retain intermediate .hc files.
843 -keep-hi-files
845 Retain intermediate .hi files (the default).
846 -keep-hscpp-file
848 Retain intermediate .hscpp files.
849 -keep-llvm-file
851 Retain intermediate LLVM .ll files. Implies -fllvm.
852 -keep-o-files
854 Retain intermediate .o files (the default).
855 -keep-s-file
857 Retain intermediate .s files.
858 -keep-tmp-files
860 Retain all intermediate temporary files.
861 Language options
863 -XAllowAmbiguousTypes
864 Allow the user to write ambiguous types, and the type inference
865 engine to infer them.
866 -XApplicativeDo
868 Enable Applicative do-notation desugaring
869 -XArrows
871 Enable arrow notation extension
872 -XBangPatterns
874 Enable bang patterns.
875 -XBinaryLiterals
877 Enable support for binary literals.
878 -XBlockArguments
880 Allow do blocks and other constructs as function arguments.
881 -XCApiFFI
883 Enable the CAPI calling convention.
884 -XConstrainedClassMethods
886 Enable constrained class methods.
887 -XConstraintKinds
889 Enable a kind of constraints.
890 -XCPP Enable the C preprocessor.
892 -XCUSKs
894 Enable detection of complete user-supplied kind signatures.
895 -XDataKinds
897 Enable datatype promotion.
898 -XDatatypeContexts
900 Allow contexts on data types.
901 -XDefaultSignatures
903 Enable default signatures.
904 -XDeriveAnyClass
906 Enable deriving for any class.
907 -XDeriveDataTypeable
909 Enable deriving for the Data class. Implied by (deprecated) Au‐
910 toDeriveTypeable.
911 -XDeriveFoldable
913 Enable deriving for the Foldable class. Implied by Derive‐
914 Traversable.
915 -XDeriveFunctor
917 Enable deriving for the Functor class. Implied by Derive‐
918 Traversable.
919 -XDeriveGeneric
921 Enable deriving for the Generic class.
922 -XDeriveLift
924 Enable deriving for the Lift class
925 -XDeriveTraversable
927 Enable deriving for the Traversable class. Implies DeriveFunc‐
928 tor and DeriveFoldable.
929 -XDerivingStrategies
931 Enables deriving strategies.
932 -XDerivingVia
934 Enable deriving instances via types of the same runtime repre‐
935 sentation. Implies DerivingStrategies.
936 -XDisambiguateRecordFields
938 Enable record field disambiguation. Implied by RecordWildCards.
939 -XDuplicateRecordFields
941 Allow definition of record types with identically-named fields.
942 -XEmptyCase
944 Allow empty case alternatives.
945 -XEmptyDataDecls
947 Allow definition of empty data types.
948 -XEmptyDataDeriving
950 Allow deriving instances of standard type classes for empty data
951 types.
952 -XExistentialQuantification
954 Enable liberalised type synonyms.
955 -XExplicitForAll
957 Enable explicit universal quantification. Implied by Scoped‐
958 TypeVariables, LiberalTypeSynonyms, RankNTypes and Existen‐
959 tialQuantification.
960 -XExplicitNamespaces
962 Enable using the keyword type to specify the namespace of en‐
963 tries in imports and exports (Explicit namespaces in import/ex‐
964 port). Implied by TypeOperators and TypeFamilies.
965 -XExtendedDefaultRules
967 Use GHCi's extended default rules in a normal module.
968 -XFlexibleContexts
970 Enable flexible contexts.
971 -XFlexibleInstances
973 Enable flexible instances. Implies TypeSynonymInstances.
974 -XForeignFunctionInterface
976 Enable foreign function interface.
977 -XFunctionalDependencies
979 Enable functional dependencies. Implies MultiParamTypeClasses.
980 -XGADTs
982 Enable generalised algebraic data types. Implies GADTSyntax and
983 MonoLocalBinds.
984 -XGADTSyntax
986 Enable generalised algebraic data type syntax.
987 -XGeneralisedNewtypeDeriving
989 Enable newtype deriving.
990 -XGeneralizedNewtypeDeriving
992 Enable newtype deriving.
993 -XGHCForeignImportPrim
995 Enable prim calling convention. Intended for internal use only.
996 -XHaskell2010
998 Use the Haskell 2010 language variant.
999 -XHaskell98
1001 Use the Haskell 98 language variant.
1002 -XHexFloatLiterals
1004 Enable support for hexadecimal floating point literals.
1005 -XImplicitParams
1007 Enable Implicit Parameters.
1008 -XImportQualifiedPost
1010 ImportQualifiedPost allows the syntax import M qualified
1011 -XImpredicativeTypes
1013 Enable impredicative types. Implies RankNTypes.
1014 -XIncoherentInstances
1016 Enable incoherent instances. Implies OverlappingInstances.
1017 -XInstanceSigs
1019 Enable instance signatures.
1020 -XInterruptibleFFI
1022 Enable interruptible FFI.
1023 -XKindSignatures
1025 Enable kind signatures. Implied by TypeFamilies and PolyKinds.
1026 -XLambdaCase
1028 Enable lambda-case expressions.
1029 -XLexicalNegation
1031 Use whitespace to determine whether the minus sign stands for
1032 negation or subtraction.
1033 -XLiberalTypeSynonyms
1035 Enable liberalised type synonyms.
1036 -XLinearTypes
1038 Enable linear types.
1039 -XMagicHash
1041 Allow # as a postfix modifier on identifiers.
1042 -XMonadComprehensions
1044 Enable monad comprehensions.
1045 -XMonadFailDesugaring
1047 Enable monadfail desugaring.
1048 -XMonoLocalBinds
1050 Enable do not generalise local bindings. Implied by TypeFami‐
1051 lies and GADTs.
1052 -XMultiParamTypeClasses
1054 Enable multi parameter type classes. Implied by FunctionalDe‐
1055 pendencies.
1056 -XMultiWayIf
1058 Enable multi-way if-expressions.
1059 -XNamedFieldPuns
1061 Enable record puns.
1062 -XNamedWildCards
1064 Enable named wildcards.
1065 -XNegativeLiterals
1067 Enable support for negative literals.
1068 -XNoImplicitPrelude
1070 Don't implicitly import Prelude. Implied by RebindableSyntax.
1071 -XNoMonomorphismRestriction
1073 Disable the monomorphism restriction.
1074 -XNondecreasingIndentation
1076 Allow nested contexts to be at the same indentation level as its
1077 enclosing context.
1078 -XNoPatternGuards
1080 Disable pattern guards. Implied by Haskell98.
1081 -XNoTraditionalRecordSyntax
1083 Disable support for traditional record syntax (as supported by
1084 Haskell 98) C {f = x}
1085 -XNPlusKPatterns
1087 Enable support for n+k patterns. Implied by Haskell98.
1088 -XNullaryTypeClasses
1090 Deprecated, does nothing. nullary (no parameter) type classes
1091 are now enabled using MultiParamTypeClasses.
1092 -XNumDecimals
1094 Enable support for 'fractional' integer literals.
1095 -XNumericUnderscores
1097 Enable support for numeric underscores.
1098 -XOverlappingInstances
1100 Enable overlapping instances.
1101 -XOverloadedLabels
1103 Enable overloaded labels.
1104 -XOverloadedLists
1106 Enable overloaded lists.
1107 -XOverloadedStrings
1109 Enable overloaded string literals.
1110 -XPackageImports
1112 Enable package-qualified imports.
1113 -XParallelListComp
1115 Enable parallel list comprehensions.
1116 -XPartialTypeSignatures
1118 Enable partial type signatures.
1119 -XPatternSynonyms
1121 Enable pattern synonyms.
1122 -XPolyKinds
1124 Enable kind polymorphism. Implies KindSignatures.
1125 -XPostfixOperators
1127 Enable postfix operators.
1128 -XQualifiedDo
1130 Enable qualified do-notation desugaring.
1131 -XQuantifiedConstraints
1133 Allow forall quantifiers in constraints.
1134 -XQuasiQuotes
1136 Enable quasiquotation.
1137 -XRank2Types
1139 Enable rank-2 types. Synonym for RankNTypes.
1140 -XRankNTypes
1142 Enable rank-N types. Implied by ImpredicativeTypes.
1143 -XRebindableSyntax
1145 Employ rebindable syntax. Implies NoImplicitPrelude.
1146 -XRecordWildCards
1148 Enable record wildcards. Implies DisambiguateRecordFields.
1149 -XRecursiveDo
1151 Enable recursive do (mdo) notation.
1152 -XRoleAnnotations
1154 Enable role annotations.
1155 -XSafe Enable the Safe Haskell Safe mode.
1157 -XScopedTypeVariables
1159 Enable lexically-scoped type variables.
1160 -XStandaloneDeriving
1162 Enable standalone deriving.
1163 -XStandaloneKindSignatures
1165 Allow the use of standalone kind signatures.
1166 -XStarIsType
1168 Treat * as Data.Kind.Type.
1169 -XStaticPointers
1171 Enable static pointers.
1172 -XStrict
1174 Make bindings in the current module strict by default.
1175 -XStrictData
1177 Enable default strict datatype fields.
1178 -XTemplateHaskell
1180 Enable Template Haskell.
1181 -XTemplateHaskellQuotes
1183 Enable quotation subset of Template Haskell.
1184 -XTransformListComp
1186 Enable generalised list comprehensions.
1187 -XTrustworthy
1189 Enable the Safe Haskell Trustworthy mode.
1190 -XTupleSections
1192 Enable tuple sections.
1193 -XTypeApplications
1195 Enable type application syntax in terms and types.
1196 -XTypeFamilies
1198 Enable type families. Implies ExplicitNamespaces, KindSigna‐
1199 tures, and MonoLocalBinds.
1200 -XTypeFamilyDependencies
1202 Enable injective type families. Implies TypeFamilies.
1203 -XTypeInType
1205 Deprecated. Enable kind polymorphism and datatype promotion.
1206 -XTypeOperators
1208 Enable type operators. Implies ExplicitNamespaces.
1209 -XTypeSynonymInstances
1211 Enable type synonyms in instance heads. Implied by FlexibleIn‐
1212 stances.
1213 -XUnboxedSums
1215 Enable unboxed sums.
1216 -XUnboxedTuples
1218 Enable the use of unboxed tuple syntax.
1219 -XUndecidableInstances
1221 Enable undecidable instances.
1222 -XUndecidableSuperClasses
1224 Allow all superclass constraints, including those that may re‐
1225 sult in non-termination of the typechecker.
1226 -XUnicodeSyntax
1228 Enable unicode syntax.
1229 -XUnliftedFFITypes
1231 Enable unlifted FFI types
1232 -XUnliftedNewtypes
1234 Enable unlifted newtypes.
1235 -XUnsafe
1237 Enable Safe Haskell Unsafe mode.
1238 -XViewPatterns
1240 Enable view patterns.
1241 Linking options
1243 -c Stop after generating object (.o) file
1244 -debug Use the debugging runtime
1246 -dylib-install-name ⟨path⟩
1248 Set the install name (via -install_name passed to Apple's
1249 linker), specifying the full install path of the library file.
1250 Any libraries or executables that link with it later will pick
1251 up that path as their runtime search location for it. (Dar‐
1252 win/OS X only)
1253 -dynamic
1255 Build dynamically-linked object files and executables
1256 -dynload
1258 Selects one of a number of modes for finding shared libraries at
1259 runtime.
1260 -eventlog
1262 Enable runtime event tracing
1263 -fkeep-cafs
1265 Do not garbage-collect CAFs (top-level expressions) at runtime
1266 -flink-rts
1268 Link the runtime when generating a shared or static library
1269 -fno-embed-manifest
1271 Do not embed the manifest in the executable (Windows only)
1272 -fno-gen-manifest
1274 Do not generate a manifest file (Windows only)
1275 -fno-shared-implib
1277 Don't generate an import library for a DLL (Windows only)
1278 -framework ⟨name⟩
1280 On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This op‐
1281 tion corresponds to the -framework option for Apple's Linker.
1282 -framework-path ⟨dir⟩
1284 On Darwin/OS X/iOS only, add ⟨dir⟩ to the list of directories
1285 searched for frameworks. This option corresponds to the -F op‐
1286 tion for Apple's Linker.
1287 -fuse-rpaths
1289 Set the rpath based on -L flags
1290 -fwhole-archive-hs-libs
1292 When linking a binary executable, this inserts the flag
1293 -Wl,--whole-archive before any -l flags for Haskell libraries,
1294 and -Wl,--no-whole-archive afterwards
1295 -L ⟨dir⟩
1297 Add ⟨dir⟩ to the list of directories searched for libraries
1298 -l ⟨lib⟩
1300 Link in library ⟨lib⟩
1301 -main-is ⟨thing⟩
1303 Set main module and function
1304 -no-hs-main
1306 Don't assume this program contains main
1307 -no-rtsopts-suggestions
1309 Don't print RTS suggestions about linking with
1310 -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩].
1311 -package ⟨name⟩
1313 Expose package ⟨pkg⟩
1314 -pie Instruct the linker to produce a position-independent exe‐
1316 cutable.
1317 -rdynamic
1319 This instructs the linker to add all symbols, not only used
1320 ones, to the dynamic symbol table. Currently Linux and Win‐
1321 dows/MinGW32 only. This is equivalent to using -optl -rdynamic
1322 on Linux, and -optl -export-all-symbols on Windows.
1323 -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩]
1325 Control whether the RTS behaviour can be tweaked via com‐
1326 mand-line flags and the GHCRTS environment variable. Using none
1327 means no RTS flags can be given; some means only a minimum of
1328 safe options can be given (the default); all (or no argument at
1329 all) means that all RTS flags are permitted; ignore means RTS
1330 flags can be given, but are treated as regular arguments and
1331 passed to the Haskell program as arguments; ignoreAll is the
1332 same as ignore, but GHCRTS is also ignored. -rtsopts does not
1333 affect -with-rtsopts behavior; flags passed via -with-rtsopts
1334 are used regardless of -rtsopts.
1335 -shared
1337 Generate a shared library (as opposed to an executable)
1338 -split-sections
1340 Split sections for link-time dead-code stripping
1341 -static
1343 Use static Haskell libraries
1344 -staticlib
1346 Generate a standalone static library (as opposed to an exe‐
1347 cutable). This is useful when cross compiling. The library to‐
1348 gether with all its dependencies ends up in in a single static
1349 library that can be linked against.
1350 -threaded
1352 Use the threaded runtime
1353 -with-rtsopts=⟨opts⟩
1355 Set the default RTS options to ⟨opts⟩.
1356 Miscellaneous options
1358 -fexternal-interpreter
1359 Run interpreted code in a separate process
1360 -fglasgow-exts
1362 Deprecated. Enable most language extensions; see Controlling ex‐
1363 tensions for exactly which ones.
1364 -fno-safe-haskell
1366 Disable Safe Haskell
1367 -ghcversion-file ⟨path to ghcversion.h⟩
1369 (GHC as a C compiler only) Use this ghcversion.h file
1370 -H ⟨size⟩
1372 Set the minimum size of the heap to ⟨size⟩
1373 -j[⟨n⟩]
1375 When compiling with --make, compile ⟨n⟩ modules in parallel.
1376 Modes of operation
1378 --frontend ⟨module⟩
1379 run GHC with the given frontend plugin; see Frontend plugins for
1380 details.
1381 --help Display help
1383 --info display information about the compiler
1385 --interactive
1387 Interactive mode - normally used by just running ghci; see Using
1388 GHCi for details.
1389 --make Build a multi-module Haskell program, automatically figuring out
1391 dependencies. Likely to be much easier, and faster, than using
1392 make; see Using ghc --make for details.
1393 --mk-dll
1395 DLL-creation mode (Windows only)
1396 --numeric-version
1398 display GHC version (numeric only)
1399 --print-libdir
1401 display GHC library directory
1402 --show-iface ⟨file⟩
1404 display the contents of an interface file.
1405 --show-options
1407 display the supported command line options
1408 --supported-extensions
1410 display the supported language extensions
1411 --version
1413 display GHC version
1414 -e ⟨expr⟩
1416 Evaluate expr; see Expression evaluation mode for details.
1417 -M generate dependency information suitable for use in a Makefile;
1419 see Dependency generation for details.
1420 Individual optimizations
1422 -fasm-shortcutting
1423 Enable shortcutting on assembly. Implied by -O2.
1424 -fbinary-blob-threshold=⟨n⟩
1426 default: 500K. Tweak assembly generator for binary blobs.
1427 -fblock-layout-cfg
1429 Use the new cfg based block layout algorithm.
1430 -fblock-layout-weightless
1432 Ignore cfg weights for code layout.
1433 -fblock-layout-weights
1435 Sets edge weights used by the new code layout algorithm.
1436 -fcall-arity
1438 Enable call-arity optimisation. Implied by -O.
1439 -fcase-folding
1441 Enable constant folding in case expressions. Implied by -O.
1442 -fcase-merge
1444 Enable case-merging. Implied by -O.
1445 -fcmm-elim-common-blocks
1447 Enable Cmm common block elimination. Implied by -O.
1448 -fcmm-sink
1450 Enable Cmm sinking. Implied by -O.
1451 -fcmm-static-pred
1453 Enable static control flow prediction. Implied by -O.
1454 -fcpr-anal
1456 Turn on CPR analysis in the demand analyser. Implied by -O.
1457 -fcross-module-specialise
1459 Turn on specialisation of overloaded functions imported from
1460 other modules.
1461 -fcse Enable common sub-expression elimination. Implied by -O.
1463 -fdicts-cheap
1465 Make dictionary-valued expressions seem cheap to the optimiser.
1466 -fdicts-strict
1468 Make dictionaries strict
1469 -fdmd-tx-dict-sel
1471 Use a special demand transformer for dictionary selectors. Al‐
1472 ways enabled by default.
1473 -fdo-eta-reduction
1475 Enable eta-reduction. Implied by -O.
1476 -fdo-lambda-eta-expansion
1478 Enable lambda eta-expansion. Always enabled by default.
1479 -feager-blackholing
1481 Turn on eager blackholing
1482 -fenable-rewrite-rules
1484 Switch on all rewrite rules (including rules generated by auto‐
1485 matic specialisation of overloaded functions). Implied by -O.
1486 -fexcess-precision
1488 Enable excess intermediate precision
1489 -fexitification
1491 Enables exitification optimisation. Implied by -O.
1492 -fexpose-all-unfoldings
1494 Expose all unfoldings, even for very large or recursive func‐
1495 tions.
1496 -ffloat-in
1498 Turn on the float-in transformation. Implied by -O.
1499 -ffull-laziness
1501 Turn on full laziness (floating bindings outwards). Implied by
1502 -O.
1503 -ffun-to-thunk
1505 Allow worker-wrapper to convert a function closure into a thunk
1506 if the function does not use any of its arguments. Off by de‐
1507 fault.
1508 -fignore-asserts
1510 Ignore assertions in the source. Implied by -O.
1511 -fignore-interface-pragmas
1513 Ignore pragmas in interface files. Implied by -O0 only.
1514 -flate-dmd-anal
1516 Run demand analysis again, at the end of the simplification
1517 pipeline
1518 -flate-specialise
1520 Run a late specialisation pass
1521 -fliberate-case
1523 Turn on the liberate-case transformation. Implied by -O2.
1524 -fliberate-case-threshold=⟨n⟩
1526 default: 2000. Set the size threshold for the liberate-case
1527 transformation to ⟨n⟩
1528 -fllvm-pass-vectors-in-regs
1530 Pass vector value in vector registers for function calls
1531 -floopification
1533 Turn saturated self-recursive tail-calls into local jumps in the
1534 generated assembly. Implied by -O.
1535 -fmax-inline-alloc-size=⟨n⟩
1537 default: 128. Set the maximum size of inline array allocations
1538 to ⟨n⟩ bytes (default: 128).
1539 -fmax-inline-memcpy-insns=⟨n⟩
1541 default: 32. Inline memcpy calls if they would generate no more
1542 than ⟨n⟩ pseudo instructions.
1543 -fmax-inline-memset-insns=⟨n⟩
1545 default: 32. Inline memset calls if they would generate no more
1546 than ⟨n⟩ pseudo instructions
1547 -fmax-simplifier-iterations=⟨n⟩
1549 default: 4. Set the max iterations for the simplifier.
1550 -fmax-uncovered-patterns=⟨n⟩
1552 default: 4. Set the maximum number of patterns to display in
1553 warnings about non-exhaustive ones.
1554 -fmax-worker-args=⟨n⟩
1556 default: 10. Maximum number of value arguments for a worker.
1557 -fno-opt-coercion
1559 Turn off the coercion optimiser
1560 -fno-pre-inlining
1562 Turn off pre-inlining
1563 -fno-state-hack
1565 Turn off the state hackwhereby any lambda with a real-world
1566 state token as argument is considered to be single-entry. Hence
1567 OK to inline things inside it.
1568 -fomit-interface-pragmas
1570 Don't generate interface pragmas. Implied by -O0 only.
1571 -fomit-yields
1573 Omit heap checks when no allocation is being performed.
1574 -foptimal-applicative-do
1576 Use a slower but better algorithm for ApplicativeDo
1577 -fpedantic-bottoms
1579 Make GHC be more precise about its treatment of bottom (but see
1580 also -fno-state-hack). In particular, GHC will not eta-expand
1581 through a case expression.
1582 -fregs-graph
1584 Use the graph colouring register allocator for register alloca‐
1585 tion in the native code generator. Implied by -O2.
1586 -fregs-iterative
1588 Use the iterative coalescing graph colouring register allocator
1589 in the native code generator.
1590 -fsimpl-tick-factor=⟨n⟩
1592 default: 100. Set the percentage factor for simplifier ticks.
1593 -fsimplifier-phases=⟨n⟩
1595 default: 2. Set the number of phases for the simplifier. Ig‐
1596 nored with -O0.
1597 -fsolve-constant-dicts
1599 When solving constraints, try to eagerly solve super classes us‐
1600 ing available dictionaries.
1601 -fspec-constr
1603 Turn on the SpecConstr transformation. Implied by -O2.
1604 -fspec-constr-count=⟨n⟩
1606 default: 3.* Set to ⟨n⟩ the maximum number of specialisations
1607 that will be created for any one function by the SpecConstr
1608 transformation.
1609 -fspec-constr-keen
1611 Specialize a call with an explicit constructor argument, even if
1612 the argument is not scrutinised in the body of the function
1613 -fspec-constr-threshold=⟨n⟩
1615 default: 2000. Set the size threshold for the SpecConstr trans‐
1616 formation to ⟨n⟩.
1617 -fspecialise
1619 Turn on specialisation of overloaded functions. Implied by -O.
1620 -fspecialise-aggressively
1622 Turn on specialisation of overloaded functions regardless of
1623 size, if unfolding is available
1624 -fstatic-argument-transformation
1626 Turn on the static argument transformation.
1627 -fstg-cse
1629 Enable common sub-expression elimination on the STG intermediate
1630 language
1631 -fstg-lift-lams
1633 Enable late lambda lifting on the STG intermediate language. Im‐
1634 plied by -O2.
1635 -fstg-lift-lams-known
1637 Allow turning known into unknown calls while performing late
1638 lambda lifting.
1639 -fstg-lift-lams-non-rec-args
1641 Create top-level non-recursive functions with at most <n> param‐
1642 eters while performing late lambda lifting.
1643 -fstg-lift-lams-rec-args
1645 Create top-level recursive functions with at most <n> parameters
1646 while performing late lambda lifting.
1647 -fstrictness
1649 Turn on strictness analysis. Implied by -O. Implies
1650 -fworker-wrapper
1651 -fstrictness-before=⟨n⟩
1653 Run an additional strictness analysis before simplifier phase
1654 ⟨n⟩
1655 -funbox-small-strict-fields
1657 Flatten strict constructor fields with a pointer-sized represen‐
1658 tation. Implied by -O.
1659 -funbox-strict-fields
1661 Flatten strict constructor fields
1662 -funfolding-creation-threshold=⟨n⟩
1664 default: 750. Tweak unfolding settings.
1665 -funfolding-dict-discount=⟨n⟩
1667 default: 30. Tweak unfolding settings.
1668 -funfolding-fun-discount=⟨n⟩
1670 default: 60. Tweak unfolding settings.
1671 -funfolding-keeness-factor=⟨n⟩
1673 This has been deprecated in GHC 9.0.1.
1674 -funfolding-use-threshold=⟨n⟩
1676 default: 80. Tweak unfolding settings.
1677 -fworker-wrapper
1679 Enable the worker-wrapper transformation.
1680 Optimization levels
1682 -O Enable level 1 optimisations
1683 -O0 Disable optimisations (default)
1685 -O2 Enable level 2 optimisations
1687 -O⟨n⟩ Any -On where n > 2 is the same as -O2.
1689 Package options
1691 -clear-package-db
1692 Clear the package db stack.
1693 -distrust ⟨pkg⟩
1695 Expose package ⟨pkg⟩ and set it to be distrusted. See Safe
1696 Haskell.
1697 -distrust-all-packages
1699 Distrust all packages by default. See Safe Haskell.
1700 -fpackage-trust
1702 Enable Safe Haskell trusted package requirement for trustworthy
1703 modules.
1704 -global-package-db
1706 Add the global package db to the stack.
1707 -hide-all-packages
1709 Hide all packages by default
1710 -hide-package ⟨pkg⟩
1712 Hide package ⟨pkg⟩
1713 -ignore-package ⟨pkg⟩
1715 Ignore package ⟨pkg⟩
1716 -no-auto-link-packages
1718 Don't automatically link in the base and rts packages.
1719 -no-global-package-db
1721 Remove the global package db from the stack.
1722 -no-user-package-db
1724 Remove the user's package db from the stack.
1725 -package ⟨pkg⟩
1727 Expose package ⟨pkg⟩
1728 -package-db ⟨file⟩
1730 Add ⟨file⟩ to the package db stack.
1731 -package-env ⟨file⟩|⟨name⟩
1733 Use the specified package environment.
1734 -package-id ⟨unit-id⟩
1736 Expose package by id ⟨unit-id⟩
1737 -this-unit-id ⟨unit-id⟩
1739 Compile to be part of unit (i.e. package) ⟨unit-id⟩
1740 -trust ⟨pkg⟩
1742 Expose package ⟨pkg⟩ and set it to be trusted. See Safe Haskell.
1743 -user-package-db
1745 Add the user's package db to the stack.
1746 Phases of compilation
1748 -C Stop after generating C (.hc file)
1749 -c Stop after generating object (.o) file
1751 -E Stop after preprocessing (.hspp file)
1753 -F Enable the use of a pre-processor (set with -pgmF ⟨cmd⟩)
1755 -S Stop after generating assembly (.s file)
1757 -x ⟨suffix⟩
1759 Override default behaviour for source files
1760 Overriding external programs
1762 -pgma ⟨cmd⟩
1763 Use ⟨cmd⟩ as the assembler
1764 -pgmc ⟨cmd⟩
1766 Use ⟨cmd⟩ as the C compiler
1767 -pgmdll ⟨cmd⟩
1769 Use ⟨cmd⟩ as the DLL generator
1770 -pgmF ⟨cmd⟩
1772 Use ⟨cmd⟩ as the pre-processor (with -F only)
1773 -pgmi ⟨cmd⟩
1775 Use ⟨cmd⟩ as the external interpreter command.
1776 -pgminstall_name_tool ⟨cmd⟩
1778 Use ⟨cmd⟩ as the program to inject runpath into mach-o dylibs on
1779 macOS
1780 -pgmL ⟨cmd⟩
1782 Use ⟨cmd⟩ as the literate pre-processor
1783 -pgml ⟨cmd⟩
1785 Use ⟨cmd⟩ as the linker
1786 -pgmlc ⟨cmd⟩
1788 Use ⟨cmd⟩ as the LLVM compiler
1789 -pgmlibtool ⟨cmd⟩
1791 Use ⟨cmd⟩ as the command for libtool (with -staticlib only).
1792 -pgmlm ⟨cmd⟩
1794 Use ⟨cmd⟩ as the linker when merging object files
1795 -pgmlo ⟨cmd⟩
1797 Use ⟨cmd⟩ as the LLVM optimiser
1798 -pgmotool ⟨cmd⟩
1800 Use ⟨cmd⟩ as the program to inspect mach-o dylibs on macOS
1801 -pgmP ⟨cmd⟩
1803 Use ⟨cmd⟩ as the C pre-processor (with -cpp only)
1804 -pgms ⟨cmd⟩
1806 Use ⟨cmd⟩ as the splitter
1807 -pgmwindres ⟨cmd⟩
1809 Use ⟨cmd⟩ as the program for embedding manifests on Windows.
1810 Phase-specific options
1812 -opta ⟨option⟩
1813 pass ⟨option⟩ to the assembler
1814 -optc ⟨option⟩
1816 pass ⟨option⟩ to the C compiler
1817 -optcxx ⟨option⟩
1819 pass ⟨option⟩ to the C++ compiler
1820 -optdll ⟨option⟩
1822 pass ⟨option⟩ to the DLL generator
1823 -optF ⟨option⟩
1825 pass ⟨option⟩ to the custom pre-processor
1826 -opti ⟨option⟩
1828 pass ⟨option⟩ to the interpreter sub-process.
1829 -optL ⟨option⟩
1831 pass ⟨option⟩ to the literate pre-processor
1832 -optl ⟨option⟩
1834 pass ⟨option⟩ to the linker
1835 -optlc ⟨option⟩
1837 pass ⟨option⟩ to the LLVM compiler
1838 -optlm ⟨option⟩
1840 pass ⟨option⟩ to the linker when merging object files.
1841 -optlo ⟨option⟩
1843 pass ⟨option⟩ to the LLVM optimiser
1844 -optP ⟨option⟩
1846 pass ⟨option⟩ to cpp (with -cpp only)
1847 -optwindres ⟨option⟩
1849 pass ⟨option⟩ to windres.
1850 -pgmc-supports-no-pie
1852 Indicate that the C compiler supports -no-pie
1853 Platform-specific options
1855 -mbmi2 (x86 only) Use BMI2 for bit manipulation operations
1856 -msse2 (x86 only) Use SSE2 for floating-point operations
1858 -msse4.2
1860 (x86 only) Use SSE4.2 for floating-point operations
1861 Compiler plugins
1863 -fclear-plugins
1864 Clear the list of active plugins
1865 -fplugin-opt=⟨module⟩:⟨args⟩
1867 Give arguments to a plugin module; module must be specified with
1868 -fplugin=⟨module⟩
1869 -fplugin-trustworthy
1871 Trust the used plugins and no longer mark the compiled module as
1872 unsafe
1873 -fplugin=⟨module⟩
1875 Load a plugin exported by a given module
1876 -hide-all-plugin-packages
1878 Hide all packages for plugins by default
1879 -plugin-package ⟨pkg⟩
1881 Expose ⟨pkg⟩ for plugins
1882 -plugin-package-id ⟨pkg-id⟩
1884 Expose ⟨pkg-id⟩ for plugins
1885 Profiling
1887 -fno-prof-auto
1888 Disables any previous -fprof-auto, -fprof-auto-top, or
1889 -fprof-auto-exported options.
1890 -fno-prof-cafs
1892 Disables any previous -fprof-cafs option.
1893 -fno-prof-count-entries
1895 Do not collect entry counts
1896 -fprof-auto
1898 Auto-add SCC\ s to all bindings not marked INLINE
1899 -fprof-auto-calls
1901 Auto-add SCC\ s to all call sites
1902 -fprof-auto-exported
1904 Auto-add SCC\ s to all exported bindings not marked INLINE
1905 -fprof-auto-top
1907 Auto-add SCC\ s to all top-level bindings not marked INLINE
1908 -fprof-cafs
1910 Auto-add SCC\ s to all CAFs
1911 -prof Turn on profiling
1913 -ticky Turn on ticky-ticky profiling
1915 Program coverage
1917 -fhpc Turn on Haskell program coverage instrumentation
1918 Recompilation checking
1920 -fforce-recomp
1921 Turn off recompilation checking. This is implied by any -ddump-X
1922 option when compiling a single file (i.e. when using -c).
1923 -fignore-hpc-changes
1925 Do not recompile modules just to match changes to HPC flags.
1926 This is especially useful for avoiding recompilation when using
1927 GHCi, and is enabled by default for GHCi.
1928 -fignore-optim-changes
1930 Do not recompile modules just to match changes to optimisation
1931 flags. This is especially useful for avoiding recompilation when
1932 using GHCi, and is enabled by default for GHCi.
1933 Redirecting output
1935 --exclude-module=⟨file⟩
1936 Regard ⟨file⟩ as "stable"; i.e., exclude it from having depen‐
1937 dencies on it.
1938 -ddump-mod-cycles
1940 Dump module cycles
1941 -dep-makefile ⟨file⟩
1943 Use ⟨file⟩ as the makefile
1944 -dep-suffix ⟨suffix⟩
1946 Make dependencies that declare that files with suffix
1947 .⟨suf⟩⟨osuf⟩ depend on interface files with suffix .⟨suf⟩hi
1948 -dumpdir ⟨dir⟩
1950 redirect dump files
1951 -hcsuf ⟨suffix⟩
1953 set the suffix to use for intermediate C files
1954 -hidir ⟨dir⟩
1956 set directory for interface files
1957 -hiedir ⟨dir⟩
1959 set directory for extended interface files
1960 -hiesuf ⟨suffix⟩
1962 set the suffix to use for extended interface files
1963 -hisuf ⟨suffix⟩
1965 set the suffix to use for interface files
1966 -include-cpp-deps
1968 Include preprocessor dependencies
1969 -include-pkg-deps
1971 Regard modules imported from packages as unstable
1972 -o ⟨file⟩
1974 set output filename
1975 -odir ⟨dir⟩
1977 set directory for object files
1978 -ohi ⟨file⟩
1980 set the filename in which to put the interface
1981 -osuf ⟨suffix⟩
1983 set the output file suffix
1984 -outputdir ⟨dir⟩
1986 set output directory
1987 -stubdir ⟨dir⟩
1989 redirect FFI stub files
1990 Temporary files
1992 -tmpdir ⟨dir⟩
1993 set the directory for temporary files
1994 Verbosity options
1996 -fabstract-refinement-hole-fits
1997 default: off. Toggles whether refinements where one or more of
1998 the holes are abstract are reported.
1999 -fdefer-diagnostics
2001 Defer and group diagnostic messages by severity
2002 -fdiagnostics-color=⟨always|auto|never⟩
2004 Use colors in error messages
2005 -fdiagnostics-show-caret
2007 Whether to show snippets of original source code
2008 -ferror-spans
2010 Output full span in error messages
2011 -fhide-source-paths
2013 hide module source and object paths
2014 -fkeep-going
2016 Continue compilation as far as possible on errors
2017 -fmax-refinement-hole-fits=⟨n⟩
2019 default: 6. Set the maximum number of refinement hole fits for
2020 typed holes to display in type error messages.
2021 -fmax-relevant-binds=⟨n⟩
2023 default: 6. Set the maximum number of bindings to display in
2024 type error messages.
2025 -fmax-valid-hole-fits=⟨n⟩
2027 default: 6. Set the maximum number of valid hole fits for typed
2028 holes to display in type error messages.
2029 -fno-show-valid-hole-fits
2031 Disables showing a list of valid hole fits for typed holes in
2032 type error messages.
2033 -fno-sort-valid-hole-fits
2035 Disables the sorting of the list of valid hole fits for typed
2036 holes in type error messages.
2037 -fprint-axiom-incomps
2039 Display equation incompatibilities in closed type families
2040 -fprint-equality-relations
2042 Distinguish between equality relations when printing
2043 -fprint-expanded-synonyms
2045 In type errors, also print type-synonym-expanded types.
2046 -fprint-explicit-coercions
2048 Print coercions in types
2049 -fprint-explicit-foralls
2051 Print explicit forall quantification in types. See also Explic‐
2052 itForAll
2053 -fprint-explicit-kinds
2055 Print explicit kind foralls and kind arguments in types. See
2056 also KindSignatures
2057 -fprint-explicit-runtime-reps
2059 Print RuntimeRep variables in types which are runtime-represen‐
2060 tation polymorphic.
2061 -fprint-potential-instances
2063 display all available instances in type error messages
2064 -fprint-typechecker-elaboration
2066 Print extra information from typechecker.
2067 -fprint-unicode-syntax
2069 Use unicode syntax when printing expressions, types and kinds.
2070 See also UnicodeSyntax
2071 -frefinement-level-hole-fits=⟨n⟩
2073 default: off. Sets the level of refinement of the refinement
2074 hole fits, where level n means that hole fits of up to n holes
2075 will be considered.
2076 -freverse-errors
2078 Output errors in reverse order
2079 -fshow-docs-of-hole-fits
2081 Toggles whether to show the documentation of the valid hole fits
2082 in the output.
2083 -fshow-hole-constraints
2085 Show constraints when reporting typed holes.
2086 -fshow-hole-matches-of-hole-fits
2088 Toggles whether to show the type of the additional holes in re‐
2089 finement hole fits.
2090 -fshow-provenance-of-hole-fits
2092 Toggles whether to show the provenance of the valid hole fits in
2093 the output.
2094 -fshow-type-app-of-hole-fits
2096 Toggles whether to show the type application of the valid hole
2097 fits in the output.
2098 -fshow-type-app-vars-of-hole-fits
2100 Toggles whether to show what type each quantified variable takes
2101 in a valid hole fit.
2102 -fshow-type-of-hole-fits
2104 Toggles whether to show the type of the valid hole fits in the
2105 output.
2106 -fsort-by-size-hole-fits
2108 Sort valid hole fits by size.
2109 -fsort-by-subsumption-hole-fits
2111 Sort valid hole fits by subsumption.
2112 -funclutter-valid-hole-fits
2114 Unclutter the list of valid hole fits by not showing provenance
2115 nor type applications of suggestions.
2116 -Rghc-timing
2118 Summarise timing stats for GHC (same as +RTS -tstderr).
2119 -v verbose mode (equivalent to -v3)
2121 -v⟨n⟩ set verbosity level
2123 Warnings
2125 -fdefer-out-of-scope-variables
2126 Convert variable out of scope variables errors into warnings.
2127 Implied by -fdefer-type-errors. See also
2128 -Wdeferred-out-of-scope-variables.
2129 -fdefer-type-errors
2131 Turn type errors into warnings, deferring the error until run‐
2132 time. Implies -fdefer-typed-holes and
2133 -fdefer-out-of-scope-variables. See also -Wdeferred-type-errors
2134 -fdefer-typed-holes
2136 Convert typed hole errors into warnings, deferring the error un‐
2137 til runtime. Implied by -fdefer-type-errors. See also
2138 -Wtyped-holes.
2139 -fenable-th-splice-warnings
2141 Generate warnings for Template Haskell splices
2142 -fhelpful-errors
2144 Make suggestions for mis-spelled names.
2145 -fmax-pmcheck-models=⟨n⟩
2147 soft limit on the number of parallel models the pattern match
2148 checker should check a pattern match clause against
2149 -fshow-warning-groups
2151 show which group an emitted warning belongs to.
2152 -fvia-C
2154 use the C code generator
2155 -W enable normal warnings
2157 -w disable all warnings
2159 -Wall enable almost all warnings (details in Warnings and san‐
2161 ity-checking)
2162 -Wall-missed-specialisations
2164 warn when specialisation of any overloaded function fails.
2165 -Wauto-orphans
2167 (deprecated) Does nothing
2168 -Wcompat
2170 enable future compatibility warnings (details in Warnings and
2171 sanity-checking)
2172 -Wcompat-unqualified-imports
2174 Report unqualified imports of core libraries which are expected
2175 to cause compatibility problems in future releases.
2176 -Wcpp-undef
2178 warn on uses of the #if directive on undefined identifiers
2179 -Wdefault
2181 enable default flags
2182 -Wdeferred-out-of-scope-variables
2184 Report warnings when variable out-of-scope errors are deferred
2185 until runtime. See -fdefer-out-of-scope-variables.
2186 -Wdeferred-type-errors
2188 Report warnings when deferred type errors are enabled. This op‐
2189 tion is enabled by default. See -fdefer-type-errors.
2190 -Wdeprecated-flags
2192 warn about uses of commandline flags that are deprecated
2193 -Wdeprecations
2195 warn about uses of functions & types that have warnings or dep‐
2196 recated pragmas. Alias for -Wwarnings-deprecations
2197 -Wderiving-defaults
2199 warn about default deriving when using both DeriveAnyClass and
2200 GeneralizedNewtypeDeriving
2201 -Wderiving-typeable
2203 warn when Typeable is derived
2204 -Wdodgy-exports
2206 warn about dodgy exports
2207 -Wdodgy-foreign-imports
2209 warn about dodgy foreign imports
2210 -Wdodgy-imports
2212 warn about dodgy imports
2213 -Wduplicate-constraints
2215 warn when a constraint appears duplicated in a type signature
2216 -Wduplicate-exports
2218 warn when an entity is exported multiple times
2219 -Wempty-enumerations
2221 warn about enumerations that are empty
2222 -Werror
2224 make warnings fatal
2225 -Weverything
2227 enable all warnings supported by GHC
2228 -Whi-shadowing
2230 (deprecated) warn when a .hi file in the current directory shad‐
2231 ows a library
2232 -Widentities
2234 warn about uses of Prelude numeric conversions that are probably
2235 the identity (and hence could be omitted)
2236 -Wimplicit-kind-vars
2238 warn when kind variables are implicitly quantified over.
2239 -Wimplicit-prelude
2241 warn when the Prelude is implicitly imported
2242 -Winaccessible-code
2244 warn about inaccessible code
2245 -Wincomplete-patterns
2247 warn when a pattern match could fail
2248 -Wincomplete-record-updates
2250 warn when a record update could fail
2251 -Wincomplete-uni-patterns
2253 warn when a pattern match in a lambda expression or pattern
2254 binding could fail
2255 -Winferred-safe-imports
2257 warn when an explicitly Safe Haskell module imports a Safe-In‐
2258 ferred one
2259 -Winline-rule-shadowing
2261 Warn if a rewrite RULE might fail to fire because the function
2262 might be inlined before the rule has a chance to fire. See How
2263 rules interact with INLINE/NOINLINE pragmas.
2264 -Winvalid-haddock
2266 warn when a Haddock comment occurs in an invalid position
2267 -Wmissed-extra-shared-lib
2269 Warn when GHCi can't load a shared lib.
2270 -Wmissed-specialisations
2272 warn when specialisation of an imported, overloaded function
2273 fails.
2274 -Wmissing-deriving-strategies
2276 warn when a deriving clause is missing a deriving strategy
2277 -Wmissing-export-lists
2279 warn when a module declaration does not explicitly list all ex‐
2280 ports
2281 -Wmissing-exported-signatures
2283 warn about top-level functions without signatures, only if they
2284 are exported. takes precedence over -Wmissing-signatures
2285 -Wmissing-exported-sigs
2287 (deprecated) warn about top-level functions without signatures,
2288 only if they are exported. takes precedence over -Wmissing-sig‐
2289 natures
2290 -Wmissing-fields
2292 warn when fields of a record are uninitialised
2293 -Wmissing-home-modules
2295 warn when encountering a home module imported, but not listed on
2296 the command line. Useful for cabal to ensure GHC won't pick up
2297 modules, not listed neither in exposed-modules, nor in
2298 other-modules.
2299 -Wmissing-import-lists
2301 warn when an import declaration does not explicitly list all the
2302 names brought into scope
2303 -Wmissing-local-signatures
2305 warn about polymorphic local bindings without signatures
2306 -Wmissing-local-sigs
2308 (deprecated) warn about polymorphic local bindings without sig‐
2309 natures
2310 -Wmissing-methods
2312 warn when class methods are undefined
2313 -Wmissing-monadfail-instances
2315 Warn when a failable pattern is used in a do-block that does not
2316 have a MonadFail instance.
2317 -Wmissing-pattern-synonym-signatures
2319 warn when pattern synonyms do not have type signatures
2320 -Wmissing-safe-haskell-mode
2322 warn when the Safe Haskell mode is not explicitly specified.
2323 -Wmissing-signatures
2325 warn about top-level functions without signatures
2326 -Wmissing-space-after-bang
2328 (deprecated) Does nothing
2329 -Wmonomorphism-restriction
2331 warn when the Monomorphism Restriction is applied
2332 -Wname-shadowing
2334 warn when names are shadowed
2335 -Wno-compat
2337 Disables all warnings enabled by -Wcompat.
2338 -Wnoncanonical-monad-instances
2340 warn when Applicative or Monad instances have noncanonical defi‐
2341 nitions of return, pure, (>>), or (*>). See flag description in
2342 Warnings and sanity-checking for more details.
2343 -Wnoncanonical-monadfail-instances
2345 warn when Monad or MonadFail instances have noncanonical defini‐
2346 tions of fail. See flag description in Warnings and san‐
2347 ity-checking for more details.
2348 -Wnoncanonical-monoid-instances
2350 warn when Semigroup or Monoid instances have noncanonical defi‐
2351 nitions of (<>) or mappend. See flag description in Warnings
2352 and sanity-checking for more details.
2353 -Worphans
2355 warn when the module contains orphan instance declarations or
2356 rewrite rules
2357 -Woverflowed-literals
2359 warn about literals that will overflow their type
2360 -Woverlapping-patterns
2362 warn about overlapping patterns
2363 -Wpartial-fields
2365 warn when defining a partial record field.
2366 -Wpartial-type-signatures
2368 warn about holes in partial type signatures when PartialTypeSig‐
2369 natures is enabled. Not applicable when PartialTypeSignatures is
2370 not enabled, in which case errors are generated for such holes.
2371 -Wredundant-constraints
2373 Have the compiler warn about redundant constraints in type sig‐
2374 natures.
2375 -Wredundant-record-wildcards
2377 Warn about record wildcard matches when the wildcard binds no
2378 patterns.
2379 -Wsafe warn if the module being compiled is regarded to be safe.
2381 -Wsemigroup
2383 warn when a Monoid is not Semigroup, and on non- Semigroup defi‐
2384 nitions of (<>)?
2385 -Wsimplifiable-class-constraints
2387 Warn about class constraints in a type signature that can be
2388 simplified using a top-level instance declaration.
2389 -Wstar-binder
2391 warn about binding the (*) type operator despite StarIsType
2392 -Wstar-is-type
2394 warn when * is used to mean Data.Kind.Type
2395 -Wtabs warn if there are tabs in the source file
2397 -Wtrustworthy-safe
2399 warn if the module being compiled is marked as Trustworthy but
2400 it could instead be marked as Safe, a more informative bound.
2401 -Wtype-defaults
2403 warn when defaulting happens
2404 -Wtyped-holes
2406 Report warnings when typed hole errors are deferred until run‐
2407 time. See -fdefer-typed-holes.
2408 -Wunbanged-strict-patterns
2410 warn on pattern bind of unlifted variable that is neither bare
2411 nor banged
2412 -Wunicode-bidirectional-format-characters
2414 warn about the usage of unicode bidirectional layout override
2415 characters
2416 -Wunrecognised-pragmas
2418 warn about uses of pragmas that GHC doesn't recognise
2419 -Wunrecognised-warning-flags
2421 throw a warning when an unrecognised -W... flag is encountered
2422 on the command line.
2423 -Wunsafe
2425 warn if the module being compiled is regarded to be unsafe. See
2426 Safe Haskell
2427 -Wunsupported-calling-conventions
2429 warn about use of an unsupported calling convention
2430 -Wunsupported-llvm-version
2432 Warn when using -fllvm with an unsupported version of LLVM.
2433 -Wunticked-promoted-constructors
2435 warn if promoted constructors are not ticked
2436 -Wunused-binds
2438 warn about bindings that are unused. Alias for
2439 -Wunused-top-binds, -Wunused-local-binds and
2440 -Wunused-pattern-binds
2441 -Wunused-do-bind
2443 warn about do bindings that appear to throw away values of types
2444 other than ()
2445 -Wunused-foralls
2447 warn about type variables in user-written forall\s that are un‐
2448 used
2449 -Wunused-imports
2451 warn about unnecessary imports
2452 -Wunused-local-binds
2454 warn about local bindings that are unused
2455 -Wunused-matches
2457 warn about variables in patterns that aren't used
2458 -Wunused-packages
2460 warn when package is requested on command line, but was never
2461 loaded.
2462 -Wunused-pattern-binds
2464 warn about pattern match bindings that are unused
2465 -Wunused-record-wildcards
2467 Warn about record wildcard matches when none of the bound vari‐
2468 ables are used.
2469 -Wunused-top-binds
2471 warn about top-level bindings that are unused
2472 -Wunused-type-patterns
2474 warn about unused type variables which arise from patterns in in
2475 type family and data family instances
2476 -Wwarn make warnings non-fatal
2478 -Wwarnings-deprecations
2480 warn about uses of functions & types that have warnings or dep‐
2481 recated pragmas
2482 -Wwrong-do-bind
2484 warn about do bindings that appear to throw away monadic values
2485 that you should have bound instead
2486
2488 Copyright 2015. The University Court of the University of Glasgow. All
2489 rights reserved.
2490
2492 https://www.haskell.org/ghc the GHC homepage
2493
2495 The GHC Team
2496
2498 2022, GHC Team
24999.0.2 Jul 21, 2022 GHC(1)