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_OmitBlackHoling,
  89         opt_OmitInterfacePragmas,
  90         opt_NoPruneTyDecls,
  91         opt_NoPruneDecls,
  92         opt_Static,
  93         opt_Unregisterised,
  94         opt_Verbose
  95     ) where
  96
  97 #include "HsVersions.h"
  98
  99 import Array    ( array, (//) )
 100 import GlaExts
 101 import IOExts   ( IORef, readIORef )
 102 import Constants        -- Default values for some flags
 103 import Util
 104 import FastTypes
 105
 106 import Maybes           ( firstJust )
 107 import Panic            ( panic )
 108
 109 #if __GLASGOW_HASKELL__ < 301
 110 import ArrBase  ( Array(..) )
 111 #else
 112 import PrelArr  ( Array(..) )
 113 #endif
 114 \end{code}
 115
 116 %************************************************************************
 117 %*                                                                      *
 118 \subsection{Command-line options}
 119 %*                                                                      *
 120 %************************************************************************
 121
 122 The hsc command-line options are split into two categories:
 123
 124   - static flags
 125   - dynamic flags
 126
 127 Static flags are represented by top-level values of type Bool or Int,
 128 for example.  They therefore have the same value throughout the
 129 invocation of hsc.
 130
 131 Dynamic flags are represented by an abstract type, DynFlags, which is
 132 passed into hsc by the compilation manager for every compilation.
 133 Dynamic flags are those that change on a per-compilation basis,
 134 perhaps because they may be present in the OPTIONS pragma at the top
 135 of a module.
 136
 137 Other flag-related blurb:
 138
 139 A list of {\em ToDo}s is things to be done in a particular part of
 140 processing.  A (fictitious) example for the Core-to-Core simplifier
 141 might be: run the simplifier, then run the strictness analyser, then
 142 run the simplifier again (three ``todos'').
 143
 144 There are three ``to-do processing centers'' at the moment.  In the
 145 main loop (\tr{main/Main.lhs}), in the Core-to-Core processing loop
 146 (\tr{simplCore/SimplCore.lhs), and in the STG-to-STG processing loop
 147 (\tr{simplStg/SimplStg.lhs}).
 148
 149 %************************************************************************
 150 %*                                                                      *
 151 \subsection{Datatypes associated with command-line options}
 152 %*                                                                      *
 153 %************************************************************************
 154
 155 \begin{code}
 156 data SwitchResult
 157   = SwBool      Bool            -- on/off
 158   | SwString    FAST_STRING     -- nothing or a String
 159   | SwInt       Int             -- nothing or an Int
 160 \end{code}
 161
 162 \begin{code}
 163 data CoreToDo           -- These are diff core-to-core passes,
 164                         -- which may be invoked in any order,
 165                         -- as many times as you like.
 166
 167   = CoreDoSimplify      -- The core-to-core simplifier.
 168         (SimplifierSwitch -> SwitchResult)
 169                         -- Each run of the simplifier can take a different
 170                         -- set of simplifier-specific flags.
 171   | CoreDoFloatInwards
 172   | CoreDoFloatOutwards Bool    -- True <=> float lambdas to top level
 173   | CoreLiberateCase
 174   | CoreDoPrintCore
 175   | CoreDoStaticArgs
 176   | CoreDoStrictness
 177   | CoreDoWorkerWrapper
 178   | CoreDoSpecialising
 179   | CoreDoUSPInf
 180   | CoreDoCPResult
 181   | CoreDoGlomBinds
 182   | CoreCSE
 183
 184   | CoreDoNothing        -- useful when building up lists of these things
 185 \end{code}
 186
 187 \begin{code}
 188 data StgToDo
 189   = StgDoStaticArgs
 190   | StgDoLambdaLift
 191   | StgDoMassageForProfiling  -- should be (next to) last
 192   -- There's also setStgVarInfo, but its absolute "lastness"
 193   -- is so critical that it is hardwired in (no flag).
 194   | D_stg_stats
 195 \end{code}
 196
 197 \begin{code}
 198 data SimplifierSwitch
 199   = MaxSimplifierIterations Int
 200   | SimplInlinePhase Int
 201   | DontApplyRules
 202   | NoCaseOfCase
 203   | SimplLetToCase
 204 \end{code}
 205
 206 %************************************************************************
 207 %*                                                                      *
 208 \subsection{Dynamic command-line options}
 209 %*                                                                      *
 210 %************************************************************************
 211
 212 \begin{code}
 213 data DynFlag
 214
 215    -- debugging flags
 216    = Opt_D_dump_all
 217    | Opt_D_dump_most
 218    | Opt_D_dump_absC
 219    | Opt_D_dump_asm
 220    | Opt_D_dump_cpranal
 221    | Opt_D_dump_deriv
 222    | Opt_D_dump_ds
 223    | Opt_D_dump_flatC
 224    | Opt_D_dump_foreign
 225    | Opt_D_dump_inlinings
 226    | Opt_D_dump_occur_anal
 227    | Opt_D_dump_parsed
 228    | Opt_D_dump_realC
 229    | Opt_D_dump_rn
 230    | Opt_D_dump_simpl
 231    | Opt_D_dump_simpl_iterations
 232    | Opt_D_dump_spec
 233    | Opt_D_dump_stg
 234    | Opt_D_dump_stranal
 235    | Opt_D_dump_tc
 236    | Opt_D_dump_types
 237    | Opt_D_dump_rules
 238    | Opt_D_dump_usagesp
 239    | Opt_D_dump_cse
 240    | Opt_D_dump_worker_wrapper
 241    | Opt_D_show_passes
 242    | Opt_D_dump_rn_trace
 243    | Opt_D_dump_rn_stats
 244    | Opt_D_dump_stix
 245    | Opt_D_dump_simpl_stats
 246    | Opt_D_source_stats
 247    | Opt_D_verbose_core2core
 248    | Opt_D_verbose_stg2stg
 249    | Opt_D_dump_hi_diffs
 250    | Opt_D_dump_minimal_imports
 251    | Opt_DoCoreLinting
 252    | Opt_DoStgLinting
 253    | Opt_DoUSPLinting
 254
 255    | Opt_WarnDuplicateExports
 256    | Opt_WarnHiShadows
 257    | Opt_WarnIncompletePatterns
 258    | Opt_WarnMissingFields
 259    | Opt_WarnMissingMethods
 260    | Opt_WarnMissingSigs
 261    | Opt_WarnNameShadowing
 262    | Opt_WarnOverlappingPatterns
 263    | Opt_WarnSimplePatterns
 264    | Opt_WarnTypeDefaults
 265    | Opt_WarnUnusedBinds
 266    | Opt_WarnUnusedImports
 267    | Opt_WarnUnusedMatches
 268    | Opt_WarnDeprecations
 269
 270    -- language opts
 271    | Opt_AllowOverlappingInstances
 272    | Opt_AllowUndecidableInstances
 273    | Opt_GlasgowExts
 274    | Opt_Generics
 275    | Opt_NoImplicitPrelude
 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_OmitBlackHoling             = lookUp  SLIT("-dno-black-holing")
 426 opt_OmitInterfacePragmas        = lookUp  SLIT("-fomit-interface-pragmas")
 427
 428 -- Simplifier switches
 429 opt_SimplNoPreInlining          = lookUp SLIT("-fno-pre-inlining")
 430         -- NoPreInlining is there just to see how bad things
 431         -- get if you don't do it!
 432 opt_SimplDoEtaReduction         = lookUp SLIT("-fdo-eta-reduction")
 433 opt_SimplDoLambdaEtaExpansion   = lookUp SLIT("-fdo-lambda-eta-expansion")
 434 opt_SimplCaseOfCase             = lookUp SLIT("-fcase-of-case")
 435 opt_SimplCaseMerge              = lookUp SLIT("-fcase-merge")
 436 opt_SimplPedanticBottoms        = lookUp SLIT("-fpedantic-bottoms")
 437 opt_SimplExcessPrecision        = lookUp SLIT("-fexcess-precision")
 438
 439 -- Unfolding control
 440 opt_UF_HiFileThreshold          = lookup_def_int "-funfolding-interface-threshold" (45::Int)
 441 opt_UF_CreationThreshold        = lookup_def_int "-funfolding-creation-threshold"  (45::Int)
 442 opt_UF_UseThreshold             = lookup_def_int "-funfolding-use-threshold"       (8::Int)     -- Discounts can be big
 443 opt_UF_FunAppDiscount           = lookup_def_int "-funfolding-fun-discount"        (6::Int)     -- It's great to inline a fn
 444 opt_UF_KeenessFactor            = lookup_def_float "-funfolding-keeness-factor"    (1.5::Float)
 445 opt_UF_UpdateInPlace            = lookUp  SLIT("-funfolding-update-in-place")
 446
 447 opt_UF_CheapOp  = ( 1 :: Int)   -- Only one instruction; and the args are charged for
 448 opt_UF_DearOp   = ( 4 :: Int)
 449
 450 opt_NoPruneDecls                = lookUp SLIT("-fno-prune-decls")
 451 opt_NoPruneTyDecls              = lookUp SLIT("-fno-prune-tydecls")
 452 opt_Static                      = lookUp SLIT("-static")
 453 opt_Unregisterised              = lookUp SLIT("-funregisterised")
 454 opt_Verbose                     = lookUp SLIT("-v")
 455 \end{code}
 456
 457 %************************************************************************
 458 %*                                                                      *
 459 \subsection{List of static hsc flags}
 460 %*                                                                      *
 461 %************************************************************************
 462
 463 \begin{code}
 464 isStaticHscFlag f =
 465   f `elem` [
 466         "fauto-sccs-on-all-toplevs",
 467         "fauto-sccs-on-exported-toplevs",
 468         "fauto-sccs-on-individual-cafs",
 469         "fauto-sccs-on-dicts",
 470         "fscc-profiling",
 471         "fticky-ticky",
 472         "fall-strict",
 473         "fdicts-strict",
 474         "firrefutable-tuples",
 475         "fnumbers-strict",
 476         "fparallel",
 477         "fsmp",
 478         "fsemi-tagging",
 479         "ffoldr-build-on",
 480         "flet-no-escape",
 481         "funfold-casms-in-hi-file",
 482         "fusagesp-on",
 483         "funbox-strict-fields",
 484         "femit-extern-decls",
 485         "fglobalise-toplev-names",
 486         "fgransim",
 487         "fignore-asserts",
 488         "fignore-interface-pragmas",
 489         "fno-hi-version-check",
 490         "fno-implicit-prelude",
 491         "dno-black-holing",
 492         "fomit-interface-pragmas",
 493         "fno-pre-inlining",
 494         "fdo-eta-reduction",
 495         "fdo-lambda-eta-expansion",
 496         "fcase-of-case",
 497         "fcase-merge",
 498         "fpedantic-bottoms",
 499         "fexcess-precision",
 500         "funfolding-update-in-place",
 501         "freport-compile",
 502         "fno-prune-decls",
 503         "fno-prune-tydecls",
 504         "static",
 505         "funregisterised",
 506         "v" ]
 507   || any (flip prefixMatch f) [
 508         "fcontext-stack",
 509         "fliberate-case-threshold",
 510         "fhi-version=",
 511         "fhistory-size",
 512         "funfolding-interface-threshold",
 513         "funfolding-creation-threshold",
 514         "funfolding-use-threshold",
 515         "funfolding-fun-discount",
 516         "funfolding-keeness-factor"
 517      ]
 518 \end{code}
 519
 520 %************************************************************************
 521 %*                                                                      *
 522 \subsection{Switch ordering}
 523 %*                                                                      *
 524 %************************************************************************
 525
 526 These things behave just like enumeration types.
 527
 528 \begin{code}
 529 instance Eq SimplifierSwitch where
 530     a == b = tagOf_SimplSwitch a ==# tagOf_SimplSwitch b
 531
 532 instance Ord SimplifierSwitch where
 533     a <  b  = tagOf_SimplSwitch a <# tagOf_SimplSwitch b
 534     a <= b  = tagOf_SimplSwitch a <=# tagOf_SimplSwitch b
 535
 536
 537 tagOf_SimplSwitch (SimplInlinePhase _)          = _ILIT(1)
 538 tagOf_SimplSwitch (MaxSimplifierIterations _)   = _ILIT(2)
 539 tagOf_SimplSwitch DontApplyRules                = _ILIT(3)
 540 tagOf_SimplSwitch SimplLetToCase                = _ILIT(4)
 541 tagOf_SimplSwitch NoCaseOfCase                  = _ILIT(5)
 542
 543 -- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
 544
 545 lAST_SIMPL_SWITCH_TAG = 5
 546 \end{code}
 547
 548 %************************************************************************
 549 %*                                                                      *
 550 \subsection{Switch lookup}
 551 %*                                                                      *
 552 %************************************************************************
 553
 554 \begin{code}
 555 isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
 556 isAmongSimpl on_switches                -- Switches mentioned later occur *earlier*
 557                                         -- in the list; defaults right at the end.
 558   = let
 559         tidied_on_switches = foldl rm_dups [] on_switches
 560                 -- The fold*l* ensures that we keep the latest switches;
 561                 -- ie the ones that occur earliest in the list.
 562
 563         sw_tbl :: Array Int SwitchResult
 564         sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
 565                         all_undefined)
 566                  // defined_elems
 567
 568         all_undefined = [ (i, SwBool False) | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
 569
 570         defined_elems = map mk_assoc_elem tidied_on_switches
 571     in
 572     -- (avoid some unboxing, bounds checking, and other horrible things:)
 573 #if __GLASGOW_HASKELL__ < 405
 574     case sw_tbl of { Array bounds_who_needs_'em stuff ->
 575 #else
 576     case sw_tbl of { Array _ _ stuff ->
 577 #endif
 578     \ switch ->
 579         case (indexArray# stuff (tagOf_SimplSwitch switch)) of
 580 #if __GLASGOW_HASKELL__ < 400
 581           Lift v -> v
 582 #elif __GLASGOW_HASKELL__ < 403
 583           (# _, v #) -> v
 584 #else
 585           (# v #) -> v
 586 #endif
 587     }
 588   where
 589     mk_assoc_elem k@(MaxSimplifierIterations lvl)
 590         = (iBox (tagOf_SimplSwitch k), SwInt lvl)
 591     mk_assoc_elem k@(SimplInlinePhase n)
 592         = (iBox (tagOf_SimplSwitch k), SwInt n)
 593     mk_assoc_elem k
 594         = (iBox (tagOf_SimplSwitch k), SwBool True) -- I'm here, Mom!
 595
 596     -- cannot have duplicates if we are going to use the array thing
 597     rm_dups switches_so_far switch
 598       = if switch `is_elem` switches_so_far
 599         then switches_so_far
 600         else switch : switches_so_far
 601       where
 602         sw `is_elem` []     = False
 603         sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) ==# (tagOf_SimplSwitch s)
 604                             || sw `is_elem` ss
 605 \end{code}
 606
 607 Default settings for simplifier switches
 608
 609 \begin{code}
 610 defaultSimplSwitches = [MaxSimplifierIterations 1]
 611 \end{code}
 612
 613 %************************************************************************
 614 %*                                                                      *
 615 \subsection{Misc functions for command-line options}
 616 %*                                                                      *
 617 %************************************************************************
 618
 619
 620 \begin{code}
 621 switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
 622
 623 switchIsOn lookup_fn switch
 624   = case (lookup_fn switch) of
 625       SwBool False -> False
 626       _            -> True
 627
 628 intSwitchSet :: (switch -> SwitchResult)
 629              -> (Int -> switch)
 630              -> Maybe Int
 631
 632 intSwitchSet lookup_fn switch
 633   = case (lookup_fn (switch (panic "intSwitchSet"))) of
 634       SwInt int -> Just int
 635       _         -> Nothing
 636 \end{code}
 637
 638 \begin{code}
 639 startsWith :: String -> String -> Maybe String
 640 -- startsWith pfx (pfx++rest) = Just rest
 641
 642 startsWith []     str = Just str
 643 startsWith (c:cs) (s:ss)
 644   = if c /= s then Nothing else startsWith cs ss
 645 startsWith  _     []  = Nothing
 646
 647 endsWith  :: String -> String -> Maybe String
 648 endsWith cs ss
 649   = case (startsWith (reverse cs) (reverse ss)) of
 650       Nothing -> Nothing
 651       Just rs -> Just (reverse rs)
 652 \end{code}