ghc/compiler/main/CmdLineOpts.lhs

   1 %
   2 % (c) The University of Glasgow, 1996-2000
   3 %
   4 \section[CmdLineOpts]{Things to do with command-line options}
   5
   6 \begin{code}
   7
   8 module CmdLineOpts (
   9         CoreToDo(..),
  10         SimplifierSwitch(..), isAmongSimpl,
  11         StgToDo(..),
  12         SwitchResult(..),
  13         HscLang(..),
  14         DynFlag(..),    -- needed non-abstractly by DriverFlags
  15         DynFlags(..),
  16
  17         v_Static_hsc_opts,
  18
  19         intSwitchSet,
  20         switchIsOn,
  21         isStaticHscFlag,
  22
  23         opt_PprStyle_NoPrags,
  24         opt_PprStyle_RawTypes,
  25         opt_PprUserLength,
  26         opt_PprStyle_Debug,
  27
  28         dopt,
  29
  30         -- other dynamic flags
  31         dopt_CoreToDo,
  32         dopt_StgToDo,
  33         dopt_HscLang,
  34         dopt_OutName,
  35
  36         -- profiling opts
  37         opt_AutoSccsOnAllToplevs,
  38         opt_AutoSccsOnExportedToplevs,
  39         opt_AutoSccsOnIndividualCafs,
  40         opt_AutoSccsOnDicts,
  41         opt_SccProfilingOn,
  42         opt_DoTickyProfiling,
  43
  44         -- language opts
  45         opt_AllStrict,
  46         opt_DictsStrict,
  47         opt_MaxContextReductionDepth,
  48         opt_IrrefutableTuples,
  49         opt_NumbersStrict,
  50         opt_Parallel,
  51         opt_SMP,
  52
  53         -- optimisation opts
  54         opt_DoSemiTagging,
  55         opt_FoldrBuildOn,
  56         opt_LiberateCaseThreshold,
  57         opt_StgDoLetNoEscapes,
  58         opt_UnfoldCasms,
  59         opt_UsageSPOn,
  60         opt_UnboxStrictFields,
  61         opt_SimplNoPreInlining,
  62         opt_SimplDoEtaReduction,
  63         opt_SimplDoLambdaEtaExpansion,
  64         opt_SimplCaseOfCase,
  65         opt_SimplCaseMerge,
  66         opt_SimplPedanticBottoms,
  67         opt_SimplExcessPrecision,
  68
  69         -- Unfolding control
  70         opt_UF_HiFileThreshold,
  71         opt_UF_CreationThreshold,
  72         opt_UF_UseThreshold,
  73         opt_UF_FunAppDiscount,
  74         opt_UF_KeenessFactor,
  75         opt_UF_UpdateInPlace,
  76         opt_UF_CheapOp,
  77         opt_UF_DearOp,
  78
  79         -- misc opts
  80         opt_InPackage,
  81         opt_EmitCExternDecls,
  82         opt_EnsureSplittableC,
  83         opt_GranMacros,
  84         opt_HiVersion,
  85         opt_HistorySize,
  86         opt_IgnoreAsserts,
  87         opt_IgnoreIfacePragmas,
  88         opt_NoHiCheck,
  89         opt_OmitBlackHoling,
  90         opt_OmitInterfacePragmas,
  91         opt_NoPruneTyDecls,
  92         opt_NoPruneDecls,
  93         opt_Static,
  94         opt_Unregisterised,
  95         opt_Verbose
  96     ) where
  97
  98 #include "HsVersions.h"
  99
 100 import Array    ( array, (//) )
 101 import GlaExts
 102 import IOExts   ( IORef, readIORef )
 103 import Constants        -- Default values for some flags
 104 import Util
 105 import FastTypes
 106
 107 import Maybes           ( firstJust )
 108 import Panic            ( panic )
 109
 110 #if __GLASGOW_HASKELL__ < 301
 111 import ArrBase  ( Array(..) )
 112 #else
 113 import PrelArr  ( Array(..) )
 114 #endif
 115 \end{code}
 116
 117 %************************************************************************
 118 %*                                                                      *
 119 \subsection{Command-line options}
 120 %*                                                                      *
 121 %************************************************************************
 122
 123 The hsc command-line options are split into two categories:
 124
 125   - static flags
 126   - dynamic flags
 127
 128 Static flags are represented by top-level values of type Bool or Int,
 129 for example.  They therefore have the same value throughout the
 130 invocation of hsc.
 131
 132 Dynamic flags are represented by an abstract type, DynFlags, which is
 133 passed into hsc by the compilation manager for every compilation.
 134 Dynamic flags are those that change on a per-compilation basis,
 135 perhaps because they may be present in the OPTIONS pragma at the top
 136 of a module.
 137
 138 Other flag-related blurb:
 139
 140 A list of {\em ToDo}s is things to be done in a particular part of
 141 processing.  A (fictitious) example for the Core-to-Core simplifier
 142 might be: run the simplifier, then run the strictness analyser, then
 143 run the simplifier again (three ``todos'').
 144
 145 There are three ``to-do processing centers'' at the moment.  In the
 146 main loop (\tr{main/Main.lhs}), in the Core-to-Core processing loop
 147 (\tr{simplCore/SimplCore.lhs), and in the STG-to-STG processing loop
 148 (\tr{simplStg/SimplStg.lhs}).
 149
 150 %************************************************************************
 151 %*                                                                      *
 152 \subsection{Datatypes associated with command-line options}
 153 %*                                                                      *
 154 %************************************************************************
 155
 156 \begin{code}
 157 data SwitchResult
 158   = SwBool      Bool            -- on/off
 159   | SwString    FAST_STRING     -- nothing or a String
 160   | SwInt       Int             -- nothing or an Int
 161 \end{code}
 162
 163 \begin{code}
 164 data CoreToDo           -- These are diff core-to-core passes,
 165                         -- which may be invoked in any order,
 166                         -- as many times as you like.
 167
 168   = CoreDoSimplify      -- The core-to-core simplifier.
 169         (SimplifierSwitch -> SwitchResult)
 170                         -- Each run of the simplifier can take a different
 171                         -- set of simplifier-specific flags.
 172   | CoreDoFloatInwards
 173   | CoreDoFloatOutwards Bool    -- True <=> float lambdas to top level
 174   | CoreLiberateCase
 175   | CoreDoPrintCore
 176   | CoreDoStaticArgs
 177   | CoreDoStrictness
 178   | CoreDoWorkerWrapper
 179   | CoreDoSpecialising
 180   | CoreDoUSPInf
 181   | CoreDoCPResult
 182   | CoreDoGlomBinds
 183   | CoreCSE
 184
 185   | CoreDoNothing        -- useful when building up lists of these things
 186 \end{code}
 187
 188 \begin{code}
 189 data StgToDo
 190   = StgDoStaticArgs
 191   | StgDoLambdaLift
 192   | StgDoMassageForProfiling  -- should be (next to) last
 193   -- There's also setStgVarInfo, but its absolute "lastness"
 194   -- is so critical that it is hardwired in (no flag).
 195   | D_stg_stats
 196 \end{code}
 197
 198 \begin{code}
 199 data SimplifierSwitch
 200   = MaxSimplifierIterations Int
 201   | SimplInlinePhase Int
 202   | DontApplyRules
 203   | NoCaseOfCase
 204   | SimplLetToCase
 205 \end{code}
 206
 207 %************************************************************************
 208 %*                                                                      *
 209 \subsection{Dynamic command-line options}
 210 %*                                                                      *
 211 %************************************************************************
 212
 213 \begin{code}
 214 data DynFlag
 215
 216    -- debugging flags
 217    = Opt_D_dump_all
 218    | Opt_D_dump_most
 219    | Opt_D_dump_absC
 220    | Opt_D_dump_asm
 221    | Opt_D_dump_cpranal
 222    | Opt_D_dump_deriv
 223    | Opt_D_dump_ds
 224    | Opt_D_dump_flatC
 225    | Opt_D_dump_foreign
 226    | Opt_D_dump_inlinings
 227    | Opt_D_dump_occur_anal
 228    | Opt_D_dump_parsed
 229    | Opt_D_dump_realC
 230    | Opt_D_dump_rn
 231    | Opt_D_dump_simpl
 232    | Opt_D_dump_simpl_iterations
 233    | Opt_D_dump_spec
 234    | Opt_D_dump_stg
 235    | Opt_D_dump_stranal
 236    | Opt_D_dump_tc
 237    | Opt_D_dump_types
 238    | Opt_D_dump_rules
 239    | Opt_D_dump_usagesp
 240    | Opt_D_dump_cse
 241    | Opt_D_dump_worker_wrapper
 242    | Opt_D_show_passes
 243    | Opt_D_dump_rn_trace
 244    | Opt_D_dump_rn_stats
 245    | Opt_D_dump_stix
 246    | Opt_D_dump_simpl_stats
 247    | Opt_D_source_stats
 248    | Opt_D_verbose_core2core
 249    | Opt_D_verbose_stg2stg
 250    | Opt_D_dump_hi_diffs
 251    | Opt_D_dump_minimal_imports
 252    | Opt_DoCoreLinting
 253    | Opt_DoStgLinting
 254    | Opt_DoUSPLinting
 255
 256    | Opt_WarnDuplicateExports
 257    | Opt_WarnHiShadows
 258    | Opt_WarnIncompletePatterns
 259    | Opt_WarnMissingFields
 260    | Opt_WarnMissingMethods
 261    | Opt_WarnMissingSigs
 262    | Opt_WarnNameShadowing
 263    | Opt_WarnOverlappingPatterns
 264    | Opt_WarnSimplePatterns
 265    | Opt_WarnTypeDefaults
 266    | Opt_WarnUnusedBinds
 267    | Opt_WarnUnusedImports
 268    | Opt_WarnUnusedMatches
 269    | Opt_WarnDeprecations
 270
 271    -- language opts
 272    | Opt_AllowOverlappingInstances
 273    | Opt_AllowUndecidableInstances
 274    | Opt_GlasgowExts
 275    | Opt_Generics
 276    | Opt_NoImplicitPrelude
 277
 278    -- misc
 279    | Opt_ReportCompile
 280    deriving (Eq)
 281
 282 data DynFlags = DynFlags {
 283   coreToDo   :: [CoreToDo],
 284   stgToDo    :: [StgToDo],
 285   hscLang    :: HscLang,
 286   hscOutName :: String,  -- name of the file in which to place output
 287   flags      :: [DynFlag]
 288  }
 289
 290 dopt :: DynFlag -> DynFlags -> Bool
 291 dopt f dflags  = f `elem` (flags dflags)
 292
 293 dopt_CoreToDo :: DynFlags -> [CoreToDo]
 294 dopt_CoreToDo = coreToDo
 295
 296 dopt_StgToDo :: DynFlags -> [StgToDo]
 297 dopt_StgToDo = stgToDo
 298
 299 dopt_OutName :: DynFlags -> String
 300 dopt_OutName = hscOutName
 301
 302 data HscLang
 303   = HscC
 304   | HscAsm
 305   | HscJava
 306   | HscInterpreted
 307     deriving Eq
 308
 309 dopt_HscLang :: DynFlags -> HscLang
 310 dopt_HscLang = hscLang
 311 \end{code}
 312
 313 %************************************************************************
 314 %*                                                                      *
 315 \subsection{Classifying command-line options}
 316 %*                                                                      *
 317 %************************************************************************
 318
 319 \begin{code}
 320 -- v_Statis_hsc_opts is here to avoid a circular dependency with
 321 -- main/DriverState.
 322 GLOBAL_VAR(v_Static_hsc_opts, [], [String])
 323
 324 lookUp           :: FAST_STRING -> Bool
 325 lookup_int       :: String -> Maybe Int
 326 lookup_def_int   :: String -> Int -> Int
 327 lookup_def_float :: String -> Float -> Float
 328 lookup_str       :: String -> Maybe String
 329
 330 unpacked_static_opts = unsafePerformIO (readIORef v_Static_hsc_opts)
 331 packed_static_opts   = map _PK_ unpacked_static_opts
 332
 333 lookUp     sw = sw `elem` packed_static_opts
 334
 335 lookup_str sw = firstJust (map (startsWith sw) unpacked_static_opts)
 336
 337 lookup_int sw = case (lookup_str sw) of
 338                   Nothing -> Nothing
 339                   Just xx -> Just (read xx)
 340
 341 lookup_def_int sw def = case (lookup_str sw) of
 342                             Nothing -> def              -- Use default
 343                             Just xx -> read xx
 344
 345 lookup_def_float sw def = case (lookup_str sw) of
 346                             Nothing -> def              -- Use default
 347                             Just xx -> read xx
 348
 349
 350 {-
 351  Putting the compiler options into temporary at-files
 352  may turn out to be necessary later on if we turn hsc into
 353  a pure Win32 application where I think there's a command-line
 354  length limit of 255. unpacked_opts understands the @ option.
 355
 356 unpacked_opts :: [String]
 357 unpacked_opts =
 358   concat $
 359   map (expandAts) $
 360   map _UNPK_ argv  -- NOT ARGV any more: v_Static_hsc_opts
 361   where
 362    expandAts ('@':fname) = words (unsafePerformIO (readFile fname))
 363    expandAts l = [l]
 364 -}
 365 \end{code}
 366
 367 %************************************************************************
 368 %*                                                                      *
 369 \subsection{Static options}
 370 %*                                                                      *
 371 %************************************************************************
 372
 373 \begin{code}
 374 -- debugging opts
 375 opt_PprStyle_NoPrags            = lookUp  SLIT("-dppr-noprags")
 376 opt_PprStyle_Debug              = lookUp  SLIT("-dppr-debug")
 377 opt_PprStyle_RawTypes           = lookUp  SLIT("-dppr-rawtypes")
 378 opt_PprUserLength               = lookup_def_int "-dppr-user-length" 5 --ToDo: give this a name
 379
 380 -- profiling opts
 381 opt_AutoSccsOnAllToplevs        = lookUp  SLIT("-fauto-sccs-on-all-toplevs")
 382 opt_AutoSccsOnExportedToplevs   = lookUp  SLIT("-fauto-sccs-on-exported-toplevs")
 383 opt_AutoSccsOnIndividualCafs    = lookUp  SLIT("-fauto-sccs-on-individual-cafs")
 384 opt_AutoSccsOnDicts             = lookUp  SLIT("-fauto-sccs-on-dicts")
 385 opt_SccProfilingOn              = lookUp  SLIT("-fscc-profiling")
 386 opt_DoTickyProfiling            = lookUp  SLIT("-fticky-ticky")
 387
 388 -- language opts
 389 opt_AllStrict                   = lookUp  SLIT("-fall-strict")
 390 opt_DictsStrict                 = lookUp  SLIT("-fdicts-strict")
 391 opt_IrrefutableTuples           = lookUp  SLIT("-firrefutable-tuples")
 392 opt_MaxContextReductionDepth    = lookup_def_int "-fcontext-stack" mAX_CONTEXT_REDUCTION_DEPTH
 393 opt_NumbersStrict               = lookUp  SLIT("-fnumbers-strict")
 394 opt_Parallel                    = lookUp  SLIT("-fparallel")
 395 opt_SMP                         = lookUp  SLIT("-fsmp")
 396
 397 -- optimisation opts
 398 opt_DoSemiTagging               = lookUp  SLIT("-fsemi-tagging")
 399 opt_FoldrBuildOn                = lookUp  SLIT("-ffoldr-build-on")
 400 opt_LiberateCaseThreshold       = lookup_def_int "-fliberate-case-threshold" (10::Int)
 401 opt_StgDoLetNoEscapes           = lookUp  SLIT("-flet-no-escape")
 402 opt_UnfoldCasms                 = lookUp SLIT("-funfold-casms-in-hi-file")
 403 opt_UsageSPOn                   = lookUp  SLIT("-fusagesp-on")
 404 opt_UnboxStrictFields           = lookUp  SLIT("-funbox-strict-fields")
 405
 406 {-
 407    The optional '-inpackage=P' flag tells what package
 408    we are compiling this module for.
 409    The Prelude, for example is compiled with '-package prelude'
 410 -}
 411 opt_InPackage                   = case lookup_str "-inpackage=" of
 412                                     Just p  -> _PK_ p
 413                                     Nothing -> SLIT("Main")     -- The package name if none is specified
 414
 415 opt_EmitCExternDecls            = lookUp  SLIT("-femit-extern-decls")
 416 opt_EnsureSplittableC           = lookUp  SLIT("-fglobalise-toplev-names")
 417 opt_GranMacros                  = lookUp  SLIT("-fgransim")
 418 opt_HiVersion                   = lookup_def_int "-fhi-version=" 0 -- what version we're compiling.
 419 opt_HistorySize                 = lookup_def_int "-fhistory-size" 20
 420 opt_IgnoreAsserts               = lookUp  SLIT("-fignore-asserts")
 421 opt_IgnoreIfacePragmas          = lookUp  SLIT("-fignore-interface-pragmas")
 422 opt_NoHiCheck                   = lookUp  SLIT("-fno-hi-version-check")
 423 opt_OmitBlackHoling             = lookUp  SLIT("-dno-black-holing")
 424 opt_OmitInterfacePragmas        = lookUp  SLIT("-fomit-interface-pragmas")
 425
 426 -- Simplifier switches
 427 opt_SimplNoPreInlining          = lookUp SLIT("-fno-pre-inlining")
 428         -- NoPreInlining is there just to see how bad things
 429         -- get if you don't do it!
 430 opt_SimplDoEtaReduction         = lookUp SLIT("-fdo-eta-reduction")
 431 opt_SimplDoLambdaEtaExpansion   = lookUp SLIT("-fdo-lambda-eta-expansion")
 432 opt_SimplCaseOfCase             = lookUp SLIT("-fcase-of-case")
 433 opt_SimplCaseMerge              = lookUp SLIT("-fcase-merge")
 434 opt_SimplPedanticBottoms        = lookUp SLIT("-fpedantic-bottoms")
 435 opt_SimplExcessPrecision        = lookUp SLIT("-fexcess-precision")
 436
 437 -- Unfolding control
 438 opt_UF_HiFileThreshold          = lookup_def_int "-funfolding-interface-threshold" (45::Int)
 439 opt_UF_CreationThreshold        = lookup_def_int "-funfolding-creation-threshold"  (45::Int)
 440 opt_UF_UseThreshold             = lookup_def_int "-funfolding-use-threshold"       (8::Int)     -- Discounts can be big
 441 opt_UF_FunAppDiscount           = lookup_def_int "-funfolding-fun-discount"        (6::Int)     -- It's great to inline a fn
 442 opt_UF_KeenessFactor            = lookup_def_float "-funfolding-keeness-factor"    (1.5::Float)
 443 opt_UF_UpdateInPlace            = lookUp  SLIT("-funfolding-update-in-place")
 444
 445 opt_UF_CheapOp  = ( 1 :: Int)   -- Only one instruction; and the args are charged for
 446 opt_UF_DearOp   = ( 4 :: Int)
 447
 448 opt_NoPruneDecls                = lookUp SLIT("-fno-prune-decls")
 449 opt_NoPruneTyDecls              = lookUp SLIT("-fno-prune-tydecls")
 450 opt_Static                      = lookUp SLIT("-static")
 451 opt_Unregisterised              = lookUp SLIT("-funregisterised")
 452 opt_Verbose                     = lookUp SLIT("-v")
 453 \end{code}
 454
 455 %************************************************************************
 456 %*                                                                      *
 457 \subsection{List of static hsc flags}
 458 %*                                                                      *
 459 %************************************************************************
 460
 461 \begin{code}
 462 isStaticHscFlag f =
 463   f `elem` [
 464         "fauto-sccs-on-all-toplevs",
 465         "fauto-sccs-on-exported-toplevs",
 466         "fauto-sccs-on-individual-cafs",
 467         "fauto-sccs-on-dicts",
 468         "fscc-profiling",
 469         "fticky-ticky",
 470         "fall-strict",
 471         "fdicts-strict",
 472         "firrefutable-tuples",
 473         "fnumbers-strict",
 474         "fparallel",
 475         "fsmp",
 476         "fsemi-tagging",
 477         "ffoldr-build-on",
 478         "flet-no-escape",
 479         "funfold-casms-in-hi-file",
 480         "fusagesp-on",
 481         "funbox-strict-fields",
 482         "femit-extern-decls",
 483         "fglobalise-toplev-names",
 484         "fgransim",
 485         "fignore-asserts",
 486         "fignore-interface-pragmas",
 487         "fno-hi-version-check",
 488         "fno-implicit-prelude",
 489         "dno-black-holing",
 490         "fomit-interface-pragmas",
 491         "fno-pre-inlining",
 492         "fdo-eta-reduction",
 493         "fdo-lambda-eta-expansion",
 494         "fcase-of-case",
 495         "fcase-merge",
 496         "fpedantic-bottoms",
 497         "fexcess-precision",
 498         "funfolding-update-in-place",
 499         "freport-compile",
 500         "fno-prune-decls",
 501         "fno-prune-tydecls",
 502         "static",
 503         "funregisterised",
 504         "v" ]
 505   || any (flip prefixMatch f) [
 506         "fcontext-stack",
 507         "fliberate-case-threshold",
 508         "fhi-version=",
 509         "fhistory-size",
 510         "funfolding-interface-threshold",
 511         "funfolding-creation-threshold",
 512         "funfolding-use-threshold",
 513         "funfolding-fun-discount",
 514         "funfolding-keeness-factor"
 515      ]
 516 \end{code}
 517
 518 %************************************************************************
 519 %*                                                                      *
 520 \subsection{Switch ordering}
 521 %*                                                                      *
 522 %************************************************************************
 523
 524 These things behave just like enumeration types.
 525
 526 \begin{code}
 527 instance Eq SimplifierSwitch where
 528     a == b = tagOf_SimplSwitch a ==# tagOf_SimplSwitch b
 529
 530 instance Ord SimplifierSwitch where
 531     a <  b  = tagOf_SimplSwitch a <# tagOf_SimplSwitch b
 532     a <= b  = tagOf_SimplSwitch a <=# tagOf_SimplSwitch b
 533
 534
 535 tagOf_SimplSwitch (SimplInlinePhase _)          = _ILIT(1)
 536 tagOf_SimplSwitch (MaxSimplifierIterations _)   = _ILIT(2)
 537 tagOf_SimplSwitch DontApplyRules                = _ILIT(3)
 538 tagOf_SimplSwitch SimplLetToCase                = _ILIT(4)
 539 tagOf_SimplSwitch NoCaseOfCase                  = _ILIT(5)
 540
 541 -- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
 542
 543 lAST_SIMPL_SWITCH_TAG = 5
 544 \end{code}
 545
 546 %************************************************************************
 547 %*                                                                      *
 548 \subsection{Switch lookup}
 549 %*                                                                      *
 550 %************************************************************************
 551
 552 \begin{code}
 553 isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
 554 isAmongSimpl on_switches                -- Switches mentioned later occur *earlier*
 555                                         -- in the list; defaults right at the end.
 556   = let
 557         tidied_on_switches = foldl rm_dups [] on_switches
 558                 -- The fold*l* ensures that we keep the latest switches;
 559                 -- ie the ones that occur earliest in the list.
 560
 561         sw_tbl :: Array Int SwitchResult
 562         sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
 563                         all_undefined)
 564                  // defined_elems
 565
 566         all_undefined = [ (i, SwBool False) | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
 567
 568         defined_elems = map mk_assoc_elem tidied_on_switches
 569     in
 570     -- (avoid some unboxing, bounds checking, and other horrible things:)
 571 #if __GLASGOW_HASKELL__ < 405
 572     case sw_tbl of { Array bounds_who_needs_'em stuff ->
 573 #else
 574     case sw_tbl of { Array _ _ stuff ->
 575 #endif
 576     \ switch ->
 577         case (indexArray# stuff (tagOf_SimplSwitch switch)) of
 578 #if __GLASGOW_HASKELL__ < 400
 579           Lift v -> v
 580 #elif __GLASGOW_HASKELL__ < 403
 581           (# _, v #) -> v
 582 #else
 583           (# v #) -> v
 584 #endif
 585     }
 586   where
 587     mk_assoc_elem k@(MaxSimplifierIterations lvl)
 588         = (iBox (tagOf_SimplSwitch k), SwInt lvl)
 589     mk_assoc_elem k@(SimplInlinePhase n)
 590         = (iBox (tagOf_SimplSwitch k), SwInt n)
 591     mk_assoc_elem k
 592         = (iBox (tagOf_SimplSwitch k), SwBool True) -- I'm here, Mom!
 593
 594     -- cannot have duplicates if we are going to use the array thing
 595     rm_dups switches_so_far switch
 596       = if switch `is_elem` switches_so_far
 597         then switches_so_far
 598         else switch : switches_so_far
 599       where
 600         sw `is_elem` []     = False
 601         sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) ==# (tagOf_SimplSwitch s)
 602                             || sw `is_elem` ss
 603 \end{code}
 604
 605
 606 %************************************************************************
 607 %*                                                                      *
 608 \subsection{Misc functions for command-line options}
 609 %*                                                                      *
 610 %************************************************************************
 611
 612
 613 \begin{code}
 614 switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
 615
 616 switchIsOn lookup_fn switch
 617   = case (lookup_fn switch) of
 618       SwBool False -> False
 619       _            -> True
 620
 621 intSwitchSet :: (switch -> SwitchResult)
 622              -> (Int -> switch)
 623              -> Maybe Int
 624
 625 intSwitchSet lookup_fn switch
 626   = case (lookup_fn (switch (panic "intSwitchSet"))) of
 627       SwInt int -> Just int
 628       _         -> Nothing
 629 \end{code}
 630
 631 \begin{code}
 632 startsWith :: String -> String -> Maybe String
 633 -- startsWith pfx (pfx++rest) = Just rest
 634
 635 startsWith []     str = Just str
 636 startsWith (c:cs) (s:ss)
 637   = if c /= s then Nothing else startsWith cs ss
 638 startsWith  _     []  = Nothing
 639
 640 endsWith  :: String -> String -> Maybe String
 641 endsWith cs ss
 642   = case (startsWith (reverse cs) (reverse ss)) of
 643       Nothing -> Nothing
 644       Just rs -> Just (reverse rs)
 645 \end{code}