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_PprUserLength,
  25         opt_PprStyle_Debug,
  26
  27         dopt,
  28
  29         -- other dynamic flags
  30         dopt_CoreToDo,
  31         dopt_StgToDo,
  32         dopt_HscLang,
  33         dopt_OutName,
  34
  35         -- profiling opts
  36         opt_AutoSccsOnAllToplevs,
  37         opt_AutoSccsOnExportedToplevs,
  38         opt_AutoSccsOnIndividualCafs,
  39         opt_AutoSccsOnDicts,
  40         opt_SccProfilingOn,
  41         opt_DoTickyProfiling,
  42
  43         -- language opts
  44         opt_AllStrict,
  45         opt_DictsStrict,
  46         opt_MaxContextReductionDepth,
  47         opt_IrrefutableTuples,
  48         opt_NumbersStrict,
  49         opt_Parallel,
  50         opt_SMP,
  51
  52         -- optimisation opts
  53         opt_DoSemiTagging,
  54         opt_FoldrBuildOn,
  55         opt_LiberateCaseThreshold,
  56         opt_StgDoLetNoEscapes,
  57         opt_UnfoldCasms,
  58         opt_UsageSPOn,
  59         opt_UnboxStrictFields,
  60         opt_SimplNoPreInlining,
  61         opt_SimplDoEtaReduction,
  62         opt_SimplDoLambdaEtaExpansion,
  63         opt_SimplCaseOfCase,
  64         opt_SimplCaseMerge,
  65         opt_SimplPedanticBottoms,
  66         opt_SimplExcessPrecision,
  67
  68         -- Unfolding control
  69         opt_UF_HiFileThreshold,
  70         opt_UF_CreationThreshold,
  71         opt_UF_UseThreshold,
  72         opt_UF_FunAppDiscount,
  73         opt_UF_KeenessFactor,
  74         opt_UF_UpdateInPlace,
  75         opt_UF_CheapOp,
  76         opt_UF_DearOp,
  77
  78         -- misc opts
  79         opt_InPackage,
  80         opt_EmitCExternDecls,
  81         opt_EnsureSplittableC,
  82         opt_GranMacros,
  83         opt_HiVersion,
  84         opt_HistorySize,
  85         opt_IgnoreAsserts,
  86         opt_IgnoreIfacePragmas,
  87         opt_NoHiCheck,
  88         opt_NoImplicitPrelude,
  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
 277    -- misc
 278    | Opt_ReportCompile
 279    deriving (Eq)
 280
 281 data DynFlags = DynFlags {
 282   coreToDo   :: [CoreToDo],
 283   stgToDo    :: [StgToDo],
 284   hscLang    :: HscLang,
 285   hscOutName :: String,  -- name of the file in which to place output
 286   flags      :: [DynFlag]
 287  }
 288
 289 dopt :: DynFlag -> DynFlags -> Bool
 290 dopt f dflags  = f `elem` (flags dflags)
 291
 292 dopt_CoreToDo :: DynFlags -> [CoreToDo]
 293 dopt_CoreToDo = coreToDo
 294
 295 dopt_StgToDo :: DynFlags -> [StgToDo]
 296 dopt_StgToDo = stgToDo
 297
 298 dopt_OutName :: DynFlags -> String
 299 dopt_OutName = hscOutName
 300
 301 data HscLang
 302   = HscC
 303   | HscAsm
 304   | HscJava
 305   | HscInterpreted
 306     deriving Eq
 307
 308 dopt_HscLang :: DynFlags -> HscLang
 309 dopt_HscLang = hscLang
 310 \end{code}
 311
 312 %************************************************************************
 313 %*                                                                      *
 314 \subsection{Classifying command-line options}
 315 %*                                                                      *
 316 %************************************************************************
 317
 318 \begin{code}
 319 -- v_Statis_hsc_opts is here to avoid a circular dependency with
 320 -- main/DriverState.
 321 GLOBAL_VAR(v_Static_hsc_opts, [], [String])
 322
 323 lookUp           :: FAST_STRING -> Bool
 324 lookup_int       :: String -> Maybe Int
 325 lookup_def_int   :: String -> Int -> Int
 326 lookup_def_float :: String -> Float -> Float
 327 lookup_str       :: String -> Maybe String
 328
 329 unpacked_static_opts = unsafePerformIO (readIORef v_Static_hsc_opts)
 330 packed_static_opts   = map _PK_ unpacked_static_opts
 331
 332 lookUp     sw = sw `elem` packed_static_opts
 333
 334 lookup_str sw = firstJust (map (startsWith sw) unpacked_static_opts)
 335
 336 lookup_int sw = case (lookup_str sw) of
 337                   Nothing -> Nothing
 338                   Just xx -> Just (read xx)
 339
 340 lookup_def_int sw def = case (lookup_str sw) of
 341                             Nothing -> def              -- Use default
 342                             Just xx -> read xx
 343
 344 lookup_def_char sw def = case (lookup_str sw) of
 345                             Just (xx:_) -> xx
 346                             _           -> def          -- Use default
 347
 348 lookup_def_float sw def = case (lookup_str sw) of
 349                             Nothing -> def              -- Use default
 350                             Just xx -> read xx
 351
 352
 353 {-
 354  Putting the compiler options into temporary at-files
 355  may turn out to be necessary later on if we turn hsc into
 356  a pure Win32 application where I think there's a command-line
 357  length limit of 255. unpacked_opts understands the @ option.
 358
 359 unpacked_opts :: [String]
 360 unpacked_opts =
 361   concat $
 362   map (expandAts) $
 363   map _UNPK_ argv  -- NOT ARGV any more: v_Static_hsc_opts
 364   where
 365    expandAts ('@':fname) = words (unsafePerformIO (readFile fname))
 366    expandAts l = [l]
 367 -}
 368 \end{code}
 369
 370 %************************************************************************
 371 %*                                                                      *
 372 \subsection{Static options}
 373 %*                                                                      *
 374 %************************************************************************
 375
 376 \begin{code}
 377 -- debugging opts
 378 opt_PprStyle_NoPrags            = lookUp  SLIT("-dppr-noprags")
 379 opt_PprStyle_Debug              = lookUp  SLIT("-dppr-debug")
 380 opt_PprUserLength               = lookup_def_int "-dppr-user-length" 5 --ToDo: give this a name
 381
 382 -- profiling opts
 383 opt_AutoSccsOnAllToplevs        = lookUp  SLIT("-fauto-sccs-on-all-toplevs")
 384 opt_AutoSccsOnExportedToplevs   = lookUp  SLIT("-fauto-sccs-on-exported-toplevs")
 385 opt_AutoSccsOnIndividualCafs    = lookUp  SLIT("-fauto-sccs-on-individual-cafs")
 386 opt_AutoSccsOnDicts             = lookUp  SLIT("-fauto-sccs-on-dicts")
 387 opt_SccProfilingOn              = lookUp  SLIT("-fscc-profiling")
 388 opt_DoTickyProfiling            = lookUp  SLIT("-fticky-ticky")
 389
 390 -- language opts
 391 opt_AllStrict                   = lookUp  SLIT("-fall-strict")
 392 opt_DictsStrict                 = lookUp  SLIT("-fdicts-strict")
 393 opt_IrrefutableTuples           = lookUp  SLIT("-firrefutable-tuples")
 394 opt_MaxContextReductionDepth    = lookup_def_int "-fcontext-stack" mAX_CONTEXT_REDUCTION_DEPTH
 395 opt_NumbersStrict               = lookUp  SLIT("-fnumbers-strict")
 396 opt_Parallel                    = lookUp  SLIT("-fparallel")
 397 opt_SMP                         = lookUp  SLIT("-fsmp")
 398
 399 -- optimisation opts
 400 opt_DoSemiTagging               = lookUp  SLIT("-fsemi-tagging")
 401 opt_FoldrBuildOn                = lookUp  SLIT("-ffoldr-build-on")
 402 opt_LiberateCaseThreshold       = lookup_def_int "-fliberate-case-threshold" (10::Int)
 403 opt_StgDoLetNoEscapes           = lookUp  SLIT("-flet-no-escape")
 404 opt_UnfoldCasms                 = lookUp SLIT("-funfold-casms-in-hi-file")
 405 opt_UsageSPOn                   = lookUp  SLIT("-fusagesp-on")
 406 opt_UnboxStrictFields           = lookUp  SLIT("-funbox-strict-fields")
 407
 408 {-
 409    The optional '-inpackage=P' flag tells what package
 410    we are compiling this module for.
 411    The Prelude, for example is compiled with '-package prelude'
 412 -}
 413 opt_InPackage                   = case lookup_str "-inpackage=" of
 414                                     Just p  -> _PK_ p
 415                                     Nothing -> SLIT("Main")     -- The package name if none is specified
 416
 417 opt_EmitCExternDecls            = lookUp  SLIT("-femit-extern-decls")
 418 opt_EnsureSplittableC           = lookUp  SLIT("-fglobalise-toplev-names")
 419 opt_GranMacros                  = lookUp  SLIT("-fgransim")
 420 opt_HiVersion                   = lookup_def_int "-fhi-version=" 0 -- what version we're compiling.
 421 opt_HistorySize                 = lookup_def_int "-fhistory-size" 20
 422 opt_IgnoreAsserts               = lookUp  SLIT("-fignore-asserts")
 423 opt_IgnoreIfacePragmas          = lookUp  SLIT("-fignore-interface-pragmas")
 424 opt_NoHiCheck                   = lookUp  SLIT("-fno-hi-version-check")
 425 opt_NoImplicitPrelude           = lookUp  SLIT("-fno-implicit-prelude")
 426 opt_OmitBlackHoling             = lookUp  SLIT("-dno-black-holing")
 427 opt_OmitInterfacePragmas        = lookUp  SLIT("-fomit-interface-pragmas")
 428
 429 -- Simplifier switches
 430 opt_SimplNoPreInlining          = lookUp SLIT("-fno-pre-inlining")
 431         -- NoPreInlining is there just to see how bad things
 432         -- get if you don't do it!
 433 opt_SimplDoEtaReduction         = lookUp SLIT("-fdo-eta-reduction")
 434 opt_SimplDoLambdaEtaExpansion   = lookUp SLIT("-fdo-lambda-eta-expansion")
 435 opt_SimplCaseOfCase             = lookUp SLIT("-fcase-of-case")
 436 opt_SimplCaseMerge              = lookUp SLIT("-fcase-merge")
 437 opt_SimplPedanticBottoms        = lookUp SLIT("-fpedantic-bottoms")
 438 opt_SimplExcessPrecision        = lookUp SLIT("-fexcess-precision")
 439
 440 -- Unfolding control
 441 opt_UF_HiFileThreshold          = lookup_def_int "-funfolding-interface-threshold" (45::Int)
 442 opt_UF_CreationThreshold        = lookup_def_int "-funfolding-creation-threshold"  (45::Int)
 443 opt_UF_UseThreshold             = lookup_def_int "-funfolding-use-threshold"       (8::Int)     -- Discounts can be big
 444 opt_UF_FunAppDiscount           = lookup_def_int "-funfolding-fun-discount"        (6::Int)     -- It's great to inline a fn
 445 opt_UF_KeenessFactor            = lookup_def_float "-funfolding-keeness-factor"    (1.5::Float)
 446 opt_UF_UpdateInPlace            = lookUp  SLIT("-funfolding-update-in-place")
 447
 448 opt_UF_CheapOp  = ( 1 :: Int)   -- Only one instruction; and the args are charged for
 449 opt_UF_DearOp   = ( 4 :: Int)
 450
 451 opt_NoPruneDecls                = lookUp SLIT("-fno-prune-decls")
 452 opt_NoPruneTyDecls              = lookUp SLIT("-fno-prune-tydecls")
 453 opt_Static                      = lookUp SLIT("-static")
 454 opt_Unregisterised              = lookUp SLIT("-funregisterised")
 455 opt_Verbose                     = lookUp SLIT("-v")
 456 \end{code}
 457
 458 %************************************************************************
 459 %*                                                                      *
 460 \subsection{List of static hsc flags}
 461 %*                                                                      *
 462 %************************************************************************
 463
 464 \begin{code}
 465 isStaticHscFlag f =
 466   f `elem` [
 467         "-fauto-sccs-on-all-toplevs",
 468         "-fauto-sccs-on-exported-toplevs",
 469         "-fauto-sccs-on-individual-cafs",
 470         "-fauto-sccs-on-dicts",
 471         "-fscc-profiling",
 472         "-fticky-ticky",
 473         "-fall-strict",
 474         "-fdicts-strict",
 475         "-fgenerics",
 476         "-firrefutable-tuples",
 477         "-fnumbers-strict",
 478         "-fparallel",
 479         "-fsmp",
 480         "-fsemi-tagging",
 481         "-ffoldr-build-on",
 482         "-flet-no-escape",
 483         "-funfold-casms-in-hi-file",
 484         "-fusagesp-on",
 485         "-funbox-strict-fields",
 486         "-femit-extern-decls",
 487         "-fglobalise-toplev-names",
 488         "-fgransim",
 489         "-fignore-asserts",
 490         "-fignore-interface-pragmas",
 491         "-fno-hi-version-check",
 492         "-fno-implicit-prelude",
 493         "-dno-black-holing",
 494         "-fomit-interface-pragmas",
 495         "-fno-pre-inlining",
 496         "-fdo-eta-reduction",
 497         "-fdo-lambda-eta-expansion",
 498         "-fcase-of-case",
 499         "-fcase-merge",
 500         "-fpedantic-bottoms",
 501         "-fexcess-precision",
 502         "-funfolding-update-in-place",
 503         "-freport-compile",
 504         "-fno-prune-decls",
 505         "-fno-prune-tydecls",
 506         "-static",
 507         "-funregisterised",
 508         "-v" ]
 509   || any (flip prefixMatch f) [
 510         "-fcontext-stack",
 511         "-fliberate-case-threshold",
 512         "-fhi-version=",
 513         "-fhistory-size",
 514         "-funfolding-interface-threshold",
 515         "-funfolding-creation-threshold",
 516         "-funfolding-use-threshold",
 517         "-funfolding-fun-discount",
 518         "-funfolding-keeness-factor"
 519      ]
 520 \end{code}
 521
 522 %************************************************************************
 523 %*                                                                      *
 524 \subsection{Switch ordering}
 525 %*                                                                      *
 526 %************************************************************************
 527
 528 These things behave just like enumeration types.
 529
 530 \begin{code}
 531 instance Eq SimplifierSwitch where
 532     a == b = tagOf_SimplSwitch a ==# tagOf_SimplSwitch b
 533
 534 instance Ord SimplifierSwitch where
 535     a <  b  = tagOf_SimplSwitch a <# tagOf_SimplSwitch b
 536     a <= b  = tagOf_SimplSwitch a <=# tagOf_SimplSwitch b
 537
 538
 539 tagOf_SimplSwitch (SimplInlinePhase _)          = _ILIT(1)
 540 tagOf_SimplSwitch (MaxSimplifierIterations _)   = _ILIT(2)
 541 tagOf_SimplSwitch DontApplyRules                = _ILIT(3)
 542 tagOf_SimplSwitch SimplLetToCase                = _ILIT(4)
 543 tagOf_SimplSwitch NoCaseOfCase                  = _ILIT(5)
 544
 545 -- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
 546
 547 lAST_SIMPL_SWITCH_TAG = 5
 548 \end{code}
 549
 550 %************************************************************************
 551 %*                                                                      *
 552 \subsection{Switch lookup}
 553 %*                                                                      *
 554 %************************************************************************
 555
 556 \begin{code}
 557 isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
 558 isAmongSimpl on_switches                -- Switches mentioned later occur *earlier*
 559                                         -- in the list; defaults right at the end.
 560   = let
 561         tidied_on_switches = foldl rm_dups [] on_switches
 562                 -- The fold*l* ensures that we keep the latest switches;
 563                 -- ie the ones that occur earliest in the list.
 564
 565         sw_tbl :: Array Int SwitchResult
 566         sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
 567                         all_undefined)
 568                  // defined_elems
 569
 570         all_undefined = [ (i, SwBool False) | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
 571
 572         defined_elems = map mk_assoc_elem tidied_on_switches
 573     in
 574     -- (avoid some unboxing, bounds checking, and other horrible things:)
 575 #if __GLASGOW_HASKELL__ < 405
 576     case sw_tbl of { Array bounds_who_needs_'em stuff ->
 577 #else
 578     case sw_tbl of { Array _ _ stuff ->
 579 #endif
 580     \ switch ->
 581         case (indexArray# stuff (tagOf_SimplSwitch switch)) of
 582 #if __GLASGOW_HASKELL__ < 400
 583           Lift v -> v
 584 #elif __GLASGOW_HASKELL__ < 403
 585           (# _, v #) -> v
 586 #else
 587           (# v #) -> v
 588 #endif
 589     }
 590   where
 591     mk_assoc_elem k@(MaxSimplifierIterations lvl)
 592         = (iBox (tagOf_SimplSwitch k), SwInt lvl)
 593     mk_assoc_elem k@(SimplInlinePhase n)
 594         = (iBox (tagOf_SimplSwitch k), SwInt n)
 595     mk_assoc_elem k
 596         = (iBox (tagOf_SimplSwitch k), SwBool True) -- I'm here, Mom!
 597
 598     -- cannot have duplicates if we are going to use the array thing
 599     rm_dups switches_so_far switch
 600       = if switch `is_elem` switches_so_far
 601         then switches_so_far
 602         else switch : switches_so_far
 603       where
 604         sw `is_elem` []     = False
 605         sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) ==# (tagOf_SimplSwitch s)
 606                             || sw `is_elem` ss
 607 \end{code}
 608
 609 Default settings for simplifier switches
 610
 611 \begin{code}
 612 defaultSimplSwitches = [MaxSimplifierIterations 1]
 613 \end{code}
 614
 615 %************************************************************************
 616 %*                                                                      *
 617 \subsection{Misc functions for command-line options}
 618 %*                                                                      *
 619 %************************************************************************
 620
 621
 622 \begin{code}
 623 switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
 624
 625 switchIsOn lookup_fn switch
 626   = case (lookup_fn switch) of
 627       SwBool False -> False
 628       _            -> True
 629
 630 intSwitchSet :: (switch -> SwitchResult)
 631              -> (Int -> switch)
 632              -> Maybe Int
 633
 634 intSwitchSet lookup_fn switch
 635   = case (lookup_fn (switch (panic "intSwitchSet"))) of
 636       SwInt int -> Just int
 637       _         -> Nothing
 638 \end{code}
 639
 640 \begin{code}
 641 startsWith :: String -> String -> Maybe String
 642 -- startsWith pfx (pfx++rest) = Just rest
 643
 644 startsWith []     str = Just str
 645 startsWith (c:cs) (s:ss)
 646   = if c /= s then Nothing else startsWith cs ss
 647 startsWith  _     []  = Nothing
 648
 649 endsWith  :: String -> String -> Maybe String
 650 endsWith cs ss
 651   = case (startsWith (reverse cs) (reverse ss)) of
 652       Nothing -> Nothing
 653       Just rs -> Just (reverse rs)
 654 \end{code}