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 Argv
 104 import Constants        -- Default values for some flags
 105 import Util
 106 import FastTypes
 107
 108 import Maybes           ( firstJust )
 109 import Panic            ( panic )
 110
 111 #if __GLASGOW_HASKELL__ < 301
 112 import ArrBase  ( Array(..) )
 113 #else
 114 import PrelArr  ( Array(..) )
 115 #endif
 116 \end{code}
 117
 118 %************************************************************************
 119 %*                                                                      *
 120 \subsection{Command-line options}
 121 %*                                                                      *
 122 %************************************************************************
 123
 124 The hsc command-line options are split into two categories:
 125
 126   - static flags
 127   - dynamic flags
 128
 129 Static flags are represented by top-level values of type Bool or Int,
 130 for example.  They therefore have the same value throughout the
 131 invocation of hsc.
 132
 133 Dynamic flags are represented by an abstract type, DynFlags, which is
 134 passed into hsc by the compilation manager for every compilation.
 135 Dynamic flags are those that change on a per-compilation basis,
 136 perhaps because they may be present in the OPTIONS pragma at the top
 137 of a module.
 138
 139 Other flag-related blurb:
 140
 141 A list of {\em ToDo}s is things to be done in a particular part of
 142 processing.  A (fictitious) example for the Core-to-Core simplifier
 143 might be: run the simplifier, then run the strictness analyser, then
 144 run the simplifier again (three ``todos'').
 145
 146 There are three ``to-do processing centers'' at the moment.  In the
 147 main loop (\tr{main/Main.lhs}), in the Core-to-Core processing loop
 148 (\tr{simplCore/SimplCore.lhs), and in the STG-to-STG processing loop
 149 (\tr{simplStg/SimplStg.lhs}).
 150
 151 %************************************************************************
 152 %*                                                                      *
 153 \subsection{Datatypes associated with command-line options}
 154 %*                                                                      *
 155 %************************************************************************
 156
 157 \begin{code}
 158 data SwitchResult
 159   = SwBool      Bool            -- on/off
 160   | SwString    FAST_STRING     -- nothing or a String
 161   | SwInt       Int             -- nothing or an Int
 162 \end{code}
 163
 164 \begin{code}
 165 data CoreToDo           -- These are diff core-to-core passes,
 166                         -- which may be invoked in any order,
 167                         -- as many times as you like.
 168
 169   = CoreDoSimplify      -- The core-to-core simplifier.
 170         (SimplifierSwitch -> SwitchResult)
 171                         -- Each run of the simplifier can take a different
 172                         -- set of simplifier-specific flags.
 173   | CoreDoFloatInwards
 174   | CoreDoFloatOutwards Bool    -- True <=> float lambdas to top level
 175   | CoreLiberateCase
 176   | CoreDoPrintCore
 177   | CoreDoStaticArgs
 178   | CoreDoStrictness
 179   | CoreDoWorkerWrapper
 180   | CoreDoSpecialising
 181   | CoreDoUSPInf
 182   | CoreDoCPResult
 183   | CoreDoGlomBinds
 184   | CoreCSE
 185
 186   | CoreDoNothing        -- useful when building up lists of these things
 187 \end{code}
 188
 189 \begin{code}
 190 data StgToDo
 191   = StgDoStaticArgs
 192   | StgDoLambdaLift
 193   | StgDoMassageForProfiling  -- should be (next to) last
 194   -- There's also setStgVarInfo, but its absolute "lastness"
 195   -- is so critical that it is hardwired in (no flag).
 196   | D_stg_stats
 197 \end{code}
 198
 199 \begin{code}
 200 data SimplifierSwitch
 201   = MaxSimplifierIterations Int
 202   | SimplInlinePhase Int
 203   | DontApplyRules
 204   | NoCaseOfCase
 205   | SimplLetToCase
 206 \end{code}
 207
 208 %************************************************************************
 209 %*                                                                      *
 210 \subsection{Dynamic command-line options}
 211 %*                                                                      *
 212 %************************************************************************
 213
 214 \begin{code}
 215 data DynFlag
 216
 217    -- debugging flags
 218    = Opt_D_dump_all
 219    | Opt_D_dump_most
 220    | Opt_D_dump_absC
 221    | Opt_D_dump_asm
 222    | Opt_D_dump_cpranal
 223    | Opt_D_dump_deriv
 224    | Opt_D_dump_ds
 225    | Opt_D_dump_flatC
 226    | Opt_D_dump_foreign
 227    | Opt_D_dump_inlinings
 228    | Opt_D_dump_occur_anal
 229    | Opt_D_dump_parsed
 230    | Opt_D_dump_realC
 231    | Opt_D_dump_rn
 232    | Opt_D_dump_simpl
 233    | Opt_D_dump_simpl_iterations
 234    | Opt_D_dump_spec
 235    | Opt_D_dump_stg
 236    | Opt_D_dump_stranal
 237    | Opt_D_dump_tc
 238    | Opt_D_dump_types
 239    | Opt_D_dump_rules
 240    | Opt_D_dump_usagesp
 241    | Opt_D_dump_cse
 242    | Opt_D_dump_worker_wrapper
 243    | Opt_D_show_passes
 244    | Opt_D_dump_rn_trace
 245    | Opt_D_dump_rn_stats
 246    | Opt_D_dump_stix
 247    | Opt_D_dump_simpl_stats
 248    | Opt_D_source_stats
 249    | Opt_D_verbose_core2core
 250    | Opt_D_verbose_stg2stg
 251    | Opt_D_dump_hi_diffs
 252    | Opt_D_dump_minimal_imports
 253    | Opt_DoCoreLinting
 254    | Opt_DoStgLinting
 255    | Opt_DoUSPLinting
 256
 257    | Opt_WarnDuplicateExports
 258    | Opt_WarnHiShadows
 259    | Opt_WarnIncompletePatterns
 260    | Opt_WarnMissingFields
 261    | Opt_WarnMissingMethods
 262    | Opt_WarnMissingSigs
 263    | Opt_WarnNameShadowing
 264    | Opt_WarnOverlappingPatterns
 265    | Opt_WarnSimplePatterns
 266    | Opt_WarnTypeDefaults
 267    | Opt_WarnUnusedBinds
 268    | Opt_WarnUnusedImports
 269    | Opt_WarnUnusedMatches
 270    | Opt_WarnDeprecations
 271
 272    -- language opts
 273    | Opt_AllowOverlappingInstances
 274    | Opt_AllowUndecidableInstances
 275    | Opt_GlasgowExts
 276    | Opt_Generics
 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_char sw def = case (lookup_str sw) of
 346                             Just (xx:_) -> xx
 347                             _           -> def          -- Use default
 348
 349 lookup_def_float sw def = case (lookup_str sw) of
 350                             Nothing -> def              -- Use default
 351                             Just xx -> read xx
 352
 353
 354 {-
 355  Putting the compiler options into temporary at-files
 356  may turn out to be necessary later on if we turn hsc into
 357  a pure Win32 application where I think there's a command-line
 358  length limit of 255. unpacked_opts understands the @ option.
 359
 360 unpacked_opts :: [String]
 361 unpacked_opts =
 362   concat $
 363   map (expandAts) $
 364   map _UNPK_ argv  -- NOT ARGV any more: v_Static_hsc_opts
 365   where
 366    expandAts ('@':fname) = words (unsafePerformIO (readFile fname))
 367    expandAts l = [l]
 368 -}
 369 \end{code}
 370
 371 %************************************************************************
 372 %*                                                                      *
 373 \subsection{Static options}
 374 %*                                                                      *
 375 %************************************************************************
 376
 377 \begin{code}
 378 -- debugging opts
 379 opt_PprStyle_NoPrags            = lookUp  SLIT("-dppr-noprags")
 380 opt_PprStyle_Debug              = lookUp  SLIT("-dppr-debug")
 381 opt_PprUserLength               = lookup_def_int "-dppr-user-length" 5 --ToDo: give this a name
 382
 383 -- profiling opts
 384 opt_AutoSccsOnAllToplevs        = lookUp  SLIT("-fauto-sccs-on-all-toplevs")
 385 opt_AutoSccsOnExportedToplevs   = lookUp  SLIT("-fauto-sccs-on-exported-toplevs")
 386 opt_AutoSccsOnIndividualCafs    = lookUp  SLIT("-fauto-sccs-on-individual-cafs")
 387 opt_AutoSccsOnDicts             = lookUp  SLIT("-fauto-sccs-on-dicts")
 388 opt_SccProfilingOn              = lookUp  SLIT("-fscc-profiling")
 389 opt_DoTickyProfiling            = lookUp  SLIT("-fticky-ticky")
 390
 391 -- language opts
 392 opt_AllStrict                   = lookUp  SLIT("-fall-strict")
 393 opt_DictsStrict                 = lookUp  SLIT("-fdicts-strict")
 394 opt_IrrefutableTuples           = lookUp  SLIT("-firrefutable-tuples")
 395 opt_MaxContextReductionDepth    = lookup_def_int "-fcontext-stack" mAX_CONTEXT_REDUCTION_DEPTH
 396 opt_NumbersStrict               = lookUp  SLIT("-fnumbers-strict")
 397 opt_Parallel                    = lookUp  SLIT("-fparallel")
 398 opt_SMP                         = lookUp  SLIT("-fsmp")
 399
 400 -- optimisation opts
 401 opt_DoSemiTagging               = lookUp  SLIT("-fsemi-tagging")
 402 opt_FoldrBuildOn                = lookUp  SLIT("-ffoldr-build-on")
 403 opt_LiberateCaseThreshold       = lookup_def_int "-fliberate-case-threshold" (10::Int)
 404 opt_StgDoLetNoEscapes           = lookUp  SLIT("-flet-no-escape")
 405 opt_UnfoldCasms                 = lookUp SLIT("-funfold-casms-in-hi-file")
 406 opt_UsageSPOn                   = lookUp  SLIT("-fusagesp-on")
 407 opt_UnboxStrictFields           = lookUp  SLIT("-funbox-strict-fields")
 408
 409 {-
 410    The optional '-inpackage=P' flag tells what package
 411    we are compiling this module for.
 412    The Prelude, for example is compiled with '-package prelude'
 413 -}
 414 opt_InPackage                   = case lookup_str "-inpackage=" of
 415                                     Just p  -> _PK_ p
 416                                     Nothing -> SLIT("Main")     -- The package name if none is specified
 417
 418 opt_EmitCExternDecls            = lookUp  SLIT("-femit-extern-decls")
 419 opt_EnsureSplittableC           = lookUp  SLIT("-fglobalise-toplev-names")
 420 opt_GranMacros                  = lookUp  SLIT("-fgransim")
 421 opt_HiVersion                   = lookup_def_int "-fhi-version=" 0 -- what version we're compiling.
 422 opt_HistorySize                 = lookup_def_int "-fhistory-size" 20
 423 opt_IgnoreAsserts               = lookUp  SLIT("-fignore-asserts")
 424 opt_IgnoreIfacePragmas          = lookUp  SLIT("-fignore-interface-pragmas")
 425 opt_NoHiCheck                   = lookUp  SLIT("-fno-hi-version-check")
 426 opt_NoImplicitPrelude           = lookUp  SLIT("-fno-implicit-prelude")
 427 opt_OmitBlackHoling             = lookUp  SLIT("-dno-black-holing")
 428 opt_OmitInterfacePragmas        = lookUp  SLIT("-fomit-interface-pragmas")
 429
 430 -- Simplifier switches
 431 opt_SimplNoPreInlining          = lookUp SLIT("-fno-pre-inlining")
 432         -- NoPreInlining is there just to see how bad things
 433         -- get if you don't do it!
 434 opt_SimplDoEtaReduction         = lookUp SLIT("-fdo-eta-reduction")
 435 opt_SimplDoLambdaEtaExpansion   = lookUp SLIT("-fdo-lambda-eta-expansion")
 436 opt_SimplCaseOfCase             = lookUp SLIT("-fcase-of-case")
 437 opt_SimplCaseMerge              = lookUp SLIT("-fcase-merge")
 438 opt_SimplPedanticBottoms        = lookUp SLIT("-fpedantic-bottoms")
 439 opt_SimplExcessPrecision        = lookUp SLIT("-fexcess-precision")
 440
 441 -- Unfolding control
 442 opt_UF_HiFileThreshold          = lookup_def_int "-funfolding-interface-threshold" (45::Int)
 443 opt_UF_CreationThreshold        = lookup_def_int "-funfolding-creation-threshold"  (45::Int)
 444 opt_UF_UseThreshold             = lookup_def_int "-funfolding-use-threshold"       (8::Int)     -- Discounts can be big
 445 opt_UF_FunAppDiscount           = lookup_def_int "-funfolding-fun-discount"        (6::Int)     -- It's great to inline a fn
 446 opt_UF_KeenessFactor            = lookup_def_float "-funfolding-keeness-factor"    (1.5::Float)
 447 opt_UF_UpdateInPlace            = lookUp  SLIT("-funfolding-update-in-place")
 448
 449 opt_UF_CheapOp  = ( 1 :: Int)   -- Only one instruction; and the args are charged for
 450 opt_UF_DearOp   = ( 4 :: Int)
 451
 452 opt_NoPruneDecls                = lookUp SLIT("-fno-prune-decls")
 453 opt_NoPruneTyDecls              = lookUp SLIT("-fno-prune-tydecls")
 454 opt_Static                      = lookUp SLIT("-static")
 455 opt_Unregisterised              = lookUp SLIT("-funregisterised")
 456 opt_Verbose                     = lookUp SLIT("-v")
 457 \end{code}
 458
 459 %************************************************************************
 460 %*                                                                      *
 461 \subsection{List of static hsc flags}
 462 %*                                                                      *
 463 %************************************************************************
 464
 465 \begin{code}
 466 isStaticHscFlag f =
 467   f `elem` [
 468         "-fauto-sccs-on-all-toplevs",
 469         "-fauto-sccs-on-exported-toplevs",
 470         "-fauto-sccs-on-individual-cafs",
 471         "-fauto-sccs-on-dicts",
 472         "-fscc-profiling",
 473         "-fticky-ticky",
 474         "-fall-strict",
 475         "-fdicts-strict",
 476         "-fgenerics",
 477         "-firrefutable-tuples",
 478         "-fnumbers-strict",
 479         "-fparallel",
 480         "-fsmp",
 481         "-fsemi-tagging",
 482         "-ffoldr-build-on",
 483         "-flet-no-escape",
 484         "-funfold-casms-in-hi-file",
 485         "-fusagesp-on",
 486         "-funbox-strict-fields",
 487         "-femit-extern-decls",
 488         "-fglobalise-toplev-names",
 489         "-fgransim",
 490         "-fignore-asserts",
 491         "-fignore-interface-pragmas",
 492         "-fno-hi-version-check",
 493         "-fno-implicit-prelude",
 494         "-dno-black-holing",
 495         "-fomit-interface-pragmas",
 496         "-fno-pre-inlining",
 497         "-fdo-eta-reduction",
 498         "-fdo-lambda-eta-expansion",
 499         "-fcase-of-case",
 500         "-fcase-merge",
 501         "-fpedantic-bottoms",
 502         "-fexcess-precision",
 503         "-funfolding-update-in-place",
 504         "-freport-compile",
 505         "-fno-prune-decls",
 506         "-fno-prune-tydecls",
 507         "-static",
 508         "-funregisterised",
 509         "-v" ]
 510   || any (flip prefixMatch f) [
 511         "-fcontext-stack",
 512         "-fliberate-case-threshold",
 513         "-fhi-version=",
 514         "-fhistory-size",
 515         "-funfolding-interface-threshold",
 516         "-funfolding-creation-threshold",
 517         "-funfolding-use-threshold",
 518         "-funfolding-fun-discount",
 519         "-funfolding-keeness-factor"
 520      ]
 521 \end{code}
 522
 523 %************************************************************************
 524 %*                                                                      *
 525 \subsection{Switch ordering}
 526 %*                                                                      *
 527 %************************************************************************
 528
 529 These things behave just like enumeration types.
 530
 531 \begin{code}
 532 instance Eq SimplifierSwitch where
 533     a == b = tagOf_SimplSwitch a ==# tagOf_SimplSwitch b
 534
 535 instance Ord SimplifierSwitch where
 536     a <  b  = tagOf_SimplSwitch a <# tagOf_SimplSwitch b
 537     a <= b  = tagOf_SimplSwitch a <=# tagOf_SimplSwitch b
 538
 539
 540 tagOf_SimplSwitch (SimplInlinePhase _)          = _ILIT(1)
 541 tagOf_SimplSwitch (MaxSimplifierIterations _)   = _ILIT(2)
 542 tagOf_SimplSwitch DontApplyRules                = _ILIT(3)
 543 tagOf_SimplSwitch SimplLetToCase                = _ILIT(4)
 544 tagOf_SimplSwitch NoCaseOfCase                  = _ILIT(5)
 545
 546 -- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
 547
 548 lAST_SIMPL_SWITCH_TAG = 5
 549 \end{code}
 550
 551 %************************************************************************
 552 %*                                                                      *
 553 \subsection{Switch lookup}
 554 %*                                                                      *
 555 %************************************************************************
 556
 557 \begin{code}
 558 isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
 559 isAmongSimpl on_switches                -- Switches mentioned later occur *earlier*
 560                                         -- in the list; defaults right at the end.
 561   = let
 562         tidied_on_switches = foldl rm_dups [] on_switches
 563                 -- The fold*l* ensures that we keep the latest switches;
 564                 -- ie the ones that occur earliest in the list.
 565
 566         sw_tbl :: Array Int SwitchResult
 567         sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
 568                         all_undefined)
 569                  // defined_elems
 570
 571         all_undefined = [ (i, SwBool False) | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
 572
 573         defined_elems = map mk_assoc_elem tidied_on_switches
 574     in
 575     -- (avoid some unboxing, bounds checking, and other horrible things:)
 576 #if __GLASGOW_HASKELL__ < 405
 577     case sw_tbl of { Array bounds_who_needs_'em stuff ->
 578 #else
 579     case sw_tbl of { Array _ _ stuff ->
 580 #endif
 581     \ switch ->
 582         case (indexArray# stuff (tagOf_SimplSwitch switch)) of
 583 #if __GLASGOW_HASKELL__ < 400
 584           Lift v -> v
 585 #elif __GLASGOW_HASKELL__ < 403
 586           (# _, v #) -> v
 587 #else
 588           (# v #) -> v
 589 #endif
 590     }
 591   where
 592     mk_assoc_elem k@(MaxSimplifierIterations lvl)
 593         = (iBox (tagOf_SimplSwitch k), SwInt lvl)
 594     mk_assoc_elem k@(SimplInlinePhase n)
 595         = (iBox (tagOf_SimplSwitch k), SwInt n)
 596     mk_assoc_elem k
 597         = (iBox (tagOf_SimplSwitch k), SwBool True) -- I'm here, Mom!
 598
 599     -- cannot have duplicates if we are going to use the array thing
 600     rm_dups switches_so_far switch
 601       = if switch `is_elem` switches_so_far
 602         then switches_so_far
 603         else switch : switches_so_far
 604       where
 605         sw `is_elem` []     = False
 606         sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) ==# (tagOf_SimplSwitch s)
 607                             || sw `is_elem` ss
 608 \end{code}
 609
 610 Default settings for simplifier switches
 611
 612 \begin{code}
 613 defaultSimplSwitches = [MaxSimplifierIterations 1]
 614 \end{code}
 615
 616 %************************************************************************
 617 %*                                                                      *
 618 \subsection{Misc functions for command-line options}
 619 %*                                                                      *
 620 %************************************************************************
 621
 622
 623 \begin{code}
 624 switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
 625
 626 switchIsOn lookup_fn switch
 627   = case (lookup_fn switch) of
 628       SwBool False -> False
 629       _            -> True
 630
 631 intSwitchSet :: (switch -> SwitchResult)
 632              -> (Int -> switch)
 633              -> Maybe Int
 634
 635 intSwitchSet lookup_fn switch
 636   = case (lookup_fn (switch (panic "intSwitchSet"))) of
 637       SwInt int -> Just int
 638       _         -> Nothing
 639 \end{code}
 640
 641 \begin{code}
 642 startsWith :: String -> String -> Maybe String
 643 -- startsWith pfx (pfx++rest) = Just rest
 644
 645 startsWith []     str = Just str
 646 startsWith (c:cs) (s:ss)
 647   = if c /= s then Nothing else startsWith cs ss
 648 startsWith  _     []  = Nothing
 649
 650 endsWith  :: String -> String -> Maybe String
 651 endsWith cs ss
 652   = case (startsWith (reverse cs) (reverse ss)) of
 653       Nothing -> Nothing
 654       Just rs -> Just (reverse rs)
 655 \end{code}