2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
6 TcGenDeriv: Generating derived instance declarations
8 This module is nominally ``subordinate'' to @TcDeriv@, which is the
9 ``official'' interface to deriving-related things.
11 This is where we do all the grimy bindings' generation.
15 DerivAuxBinds, isDupAux,
27 FFoldType(..), functorLikeTraverse,
28 deepSubtypesContaining, foldDataConArgs,
30 gen_Traversable_binds,
34 #include "HsVersions.h"
44 import MkCore ( eRROR_ID )
62 import Data.List ( partition, intersperse )
66 type DerivAuxBinds = [DerivAuxBind]
68 data DerivAuxBind -- Please add these auxiliary top-level bindings
69 = GenCon2Tag TyCon -- The con2Tag for given TyCon
70 | GenTag2Con TyCon -- ...ditto tag2Con
71 | GenMaxTag TyCon -- ...and maxTag
72 -- All these generate ZERO-BASED tag operations
73 -- I.e first constructor has tag 0
75 -- Scrap your boilerplate
76 | MkDataCon DataCon -- For constructor C we get $cC :: Constr
77 | MkTyCon TyCon -- For tycon T we get $tT :: DataType
80 isDupAux :: DerivAuxBind -> DerivAuxBind -> Bool
81 isDupAux (GenCon2Tag tc1) (GenCon2Tag tc2) = tc1 == tc2
82 isDupAux (GenTag2Con tc1) (GenTag2Con tc2) = tc1 == tc2
83 isDupAux (GenMaxTag tc1) (GenMaxTag tc2) = tc1 == tc2
84 isDupAux (MkDataCon dc1) (MkDataCon dc2) = dc1 == dc2
85 isDupAux (MkTyCon tc1) (MkTyCon tc2) = tc1 == tc2
90 %************************************************************************
94 %************************************************************************
96 Here are the heuristics for the code we generate for @Eq@:
99 Let's assume we have a data type with some (possibly zero) nullary
100 data constructors and some ordinary, non-nullary ones (the rest,
101 also possibly zero of them). Here's an example, with both \tr{N}ullary
102 and \tr{O}rdinary data cons.
104 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
108 For the ordinary constructors (if any), we emit clauses to do The
112 (==) (O1 a1 b1) (O1 a2 b2) = a1 == a2 && b1 == b2
113 (==) (O2 a1) (O2 a2) = a1 == a2
114 (==) (O3 a1 b1 c1) (O3 a2 b2 c2) = a1 == a2 && b1 == b2 && c1 == c2
117 Note: if we're comparing unlifted things, e.g., if \tr{a1} and
118 \tr{a2} are \tr{Float#}s, then we have to generate
120 case (a1 `eqFloat#` a2) of
123 for that particular test.
126 If there are any nullary constructors, we emit a catch-all clause of
130 (==) a b = case (con2tag_Foo a) of { a# ->
131 case (con2tag_Foo b) of { b# ->
132 case (a# ==# b#) of {
137 If there aren't any nullary constructors, we emit a simpler
144 For the @(/=)@ method, we normally just use the default method.
146 If the type is an enumeration type, we could/may/should? generate
147 special code that calls @con2tag_Foo@, much like for @(==)@ shown
151 We thought about doing this: If we're also deriving @Ord@ for this
154 instance ... Eq (Foo ...) where
155 (==) a b = case (compare a b) of { _LT -> False; _EQ -> True ; _GT -> False}
156 (/=) a b = case (compare a b) of { _LT -> True ; _EQ -> False; _GT -> True }
158 However, that requires that \tr{Ord <whatever>} was put in the context
159 for the instance decl, which it probably wasn't, so the decls
160 produced don't get through the typechecker.
165 gen_Eq_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
166 gen_Eq_binds loc tycon
167 = (method_binds, aux_binds)
169 (nullary_cons, nonnullary_cons)
170 | isNewTyCon tycon = ([], tyConDataCons tycon)
171 | otherwise = partition isNullarySrcDataCon (tyConDataCons tycon)
173 no_nullary_cons = null nullary_cons
175 rest | no_nullary_cons
176 = case tyConSingleDataCon_maybe tycon of
178 Nothing -> -- if cons don't match, then False
179 [([nlWildPat, nlWildPat], false_Expr)]
180 | otherwise -- calc. and compare the tags
182 untag_Expr tycon [(a_RDR,ah_RDR), (b_RDR,bh_RDR)]
183 (genOpApp (nlHsVar ah_RDR) eqInt_RDR (nlHsVar bh_RDR)))]
185 aux_binds | no_nullary_cons = []
186 | otherwise = [GenCon2Tag tycon]
188 method_binds = listToBag [eq_bind, ne_bind]
189 eq_bind = mk_FunBind loc eq_RDR (map pats_etc nonnullary_cons ++ rest)
190 ne_bind = mk_easy_FunBind loc ne_RDR [a_Pat, b_Pat] (
191 nlHsApp (nlHsVar not_RDR) (nlHsPar (nlHsVarApps eq_RDR [a_RDR, b_RDR])))
193 ------------------------------------------------------------------
196 con1_pat = nlConVarPat data_con_RDR as_needed
197 con2_pat = nlConVarPat data_con_RDR bs_needed
199 data_con_RDR = getRdrName data_con
200 con_arity = length tys_needed
201 as_needed = take con_arity as_RDRs
202 bs_needed = take con_arity bs_RDRs
203 tys_needed = dataConOrigArgTys data_con
205 ([con1_pat, con2_pat], nested_eq_expr tys_needed as_needed bs_needed)
207 nested_eq_expr [] [] [] = true_Expr
208 nested_eq_expr tys as bs
209 = foldl1 and_Expr (zipWith3Equal "nested_eq" nested_eq tys as bs)
211 nested_eq ty a b = nlHsPar (eq_Expr tycon ty (nlHsVar a) (nlHsVar b))
214 %************************************************************************
218 %************************************************************************
220 Note [Generating Ord instances]
221 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
222 Suppose constructors are K1..Kn, and some are nullary.
223 The general form we generate is:
225 * Do case on first argument
234 If i = 1, 2, n-1, n, generate a single case.
237 K2 ... -> ...eq_rhs(K2)...
240 Otherwise do a tag compare against the bigger range
241 (because this is the one most likely to succeed)
242 rhs_3 case tag b of tb ->
245 K3 ... -> ...eq_rhs(K3)....
248 * To make eq_rhs(K), which knows that
251 we just want to compare (a1,b1) then (a2,b2) etc.
252 Take care on the last field to tail-call into comparing av,bv
254 * To make nullary_rhs generate this
255 case con2tag a of a# ->
259 Several special cases:
261 * Two or fewer nullary constructors: don't generate nullary_rhs
263 * Be careful about unlifted comparisons. When comparing unboxed
264 values we can't call the overloaded functions.
265 See function unliftedOrdOp
267 Note [Do not rely on compare]
268 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
269 It's a bad idea to define only 'compare', and build the other binary
270 comparisions on top of it; see Trac #2130, #4019. Reason: we don't
271 want to laboriously make a three-way comparison, only to extract a
272 binary result, something like this:
273 (>) (I# x) (I# y) = case <# x y of
275 False -> case ==# x y of
279 So for sufficiently small types (few constructors, or all nullary)
280 we generate all methods; for large ones we just use 'compare'.
283 data OrdOp = OrdCompare | OrdLT | OrdLE | OrdGE | OrdGT
286 ordMethRdr :: OrdOp -> RdrName
289 OrdCompare -> compare_RDR
296 ltResult :: OrdOp -> LHsExpr RdrName
297 -- Knowing a<b, what is the result for a `op` b?
298 ltResult OrdCompare = ltTag_Expr
299 ltResult OrdLT = true_Expr
300 ltResult OrdLE = true_Expr
301 ltResult OrdGE = false_Expr
302 ltResult OrdGT = false_Expr
305 eqResult :: OrdOp -> LHsExpr RdrName
306 -- Knowing a=b, what is the result for a `op` b?
307 eqResult OrdCompare = eqTag_Expr
308 eqResult OrdLT = false_Expr
309 eqResult OrdLE = true_Expr
310 eqResult OrdGE = true_Expr
311 eqResult OrdGT = false_Expr
314 gtResult :: OrdOp -> LHsExpr RdrName
315 -- Knowing a>b, what is the result for a `op` b?
316 gtResult OrdCompare = gtTag_Expr
317 gtResult OrdLT = false_Expr
318 gtResult OrdLE = false_Expr
319 gtResult OrdGE = true_Expr
320 gtResult OrdGT = true_Expr
323 gen_Ord_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
324 gen_Ord_binds loc tycon
325 | null tycon_data_cons -- No data-cons => invoke bale-out case
326 = (unitBag $ mk_FunBind loc compare_RDR [], [])
328 = (unitBag (mkOrdOp OrdCompare) `unionBags` other_ops, aux_binds)
330 aux_binds | single_con_type = []
331 | otherwise = [GenCon2Tag tycon]
333 -- Note [Do not rely on compare]
334 other_ops | (last_tag - first_tag) <= 2 -- 1-3 constructors
335 || null non_nullary_cons -- Or it's an enumeration
336 = listToBag (map mkOrdOp [OrdLT,OrdLE,OrdGE,OrdGT])
340 get_tag con = dataConTag con - fIRST_TAG
341 -- We want *zero-based* tags, because that's what
342 -- con2Tag returns (generated by untag_Expr)!
344 tycon_data_cons = tyConDataCons tycon
345 single_con_type = isSingleton tycon_data_cons
346 (first_con : _) = tycon_data_cons
347 (last_con : _) = reverse tycon_data_cons
348 first_tag = get_tag first_con
349 last_tag = get_tag last_con
351 (nullary_cons, non_nullary_cons) = partition isNullarySrcDataCon tycon_data_cons
354 mkOrdOp :: OrdOp -> LHsBind RdrName
355 -- Returns a binding op a b = ... compares a and b according to op ....
356 mkOrdOp op = mk_easy_FunBind loc (ordMethRdr op) [a_Pat, b_Pat] (mkOrdOpRhs op)
358 mkOrdOpRhs :: OrdOp -> LHsExpr RdrName
359 mkOrdOpRhs op -- RHS for comparing 'a' and 'b' according to op
360 | length nullary_cons <= 2 -- Two nullary or fewer, so use cases
361 = nlHsCase (nlHsVar a_RDR) $
362 map (mkOrdOpAlt op) tycon_data_cons
363 -- i.e. case a of { C1 x y -> case b of C1 x y -> ....compare x,y...
364 -- C2 x -> case b of C2 x -> ....comopare x.... }
366 | null non_nullary_cons -- All nullary, so go straight to comparing tags
369 | otherwise -- Mixed nullary and non-nullary
370 = nlHsCase (nlHsVar a_RDR) $
371 (map (mkOrdOpAlt op) non_nullary_cons
372 ++ [mkSimpleHsAlt nlWildPat (mkTagCmp op)])
375 mkOrdOpAlt :: OrdOp -> DataCon -> LMatch RdrName
376 -- Make the alternative (Ki a1 a2 .. av ->
377 mkOrdOpAlt op data_con
378 = mkSimpleHsAlt (nlConVarPat data_con_RDR as_needed) (mkInnerRhs op data_con)
380 as_needed = take (dataConSourceArity data_con) as_RDRs
381 data_con_RDR = getRdrName data_con
383 mkInnerRhs op data_con
385 = nlHsCase (nlHsVar b_RDR) [ mkInnerEqAlt op data_con ]
388 = nlHsCase (nlHsVar b_RDR) [ mkInnerEqAlt op data_con
389 , mkSimpleHsAlt nlWildPat (ltResult op) ]
391 = nlHsCase (nlHsVar b_RDR) [ mkInnerEqAlt op data_con
392 , mkSimpleHsAlt nlWildPat (gtResult op) ]
394 | tag == first_tag + 1
395 = nlHsCase (nlHsVar b_RDR) [ mkSimpleHsAlt (nlConWildPat first_con) (gtResult op)
396 , mkInnerEqAlt op data_con
397 , mkSimpleHsAlt nlWildPat (ltResult op) ]
398 | tag == last_tag - 1
399 = nlHsCase (nlHsVar b_RDR) [ mkSimpleHsAlt (nlConWildPat last_con) (ltResult op)
400 , mkInnerEqAlt op data_con
401 , mkSimpleHsAlt nlWildPat (gtResult op) ]
403 | tag > last_tag `div` 2 -- lower range is larger
404 = untag_Expr tycon [(b_RDR, bh_RDR)] $
405 nlHsIf (genOpApp (nlHsVar bh_RDR) ltInt_RDR tag_lit)
406 (gtResult op) $ -- Definitely GT
407 nlHsCase (nlHsVar b_RDR) [ mkInnerEqAlt op data_con
408 , mkSimpleHsAlt nlWildPat (ltResult op) ]
410 | otherwise -- upper range is larger
411 = untag_Expr tycon [(b_RDR, bh_RDR)] $
412 nlHsIf (genOpApp (nlHsVar bh_RDR) gtInt_RDR tag_lit)
413 (ltResult op) $ -- Definitely LT
414 nlHsCase (nlHsVar b_RDR) [ mkInnerEqAlt op data_con
415 , mkSimpleHsAlt nlWildPat (gtResult op) ]
417 tag = get_tag data_con
418 tag_lit = noLoc (HsLit (HsIntPrim (toInteger tag)))
420 mkInnerEqAlt :: OrdOp -> DataCon -> LMatch RdrName
421 -- First argument 'a' known to be built with K
422 -- Returns a case alternative Ki b1 b2 ... bv -> compare (a1,a2,...) with (b1,b2,...)
423 mkInnerEqAlt op data_con
424 = mkSimpleHsAlt (nlConVarPat data_con_RDR bs_needed) $
425 mkCompareFields tycon op (dataConOrigArgTys data_con)
427 data_con_RDR = getRdrName data_con
428 bs_needed = take (dataConSourceArity data_con) bs_RDRs
430 mkTagCmp :: OrdOp -> LHsExpr RdrName
431 -- Both constructors known to be nullary
432 -- genreates (case data2Tag a of a# -> case data2Tag b of b# -> a# `op` b#
433 mkTagCmp op = untag_Expr tycon [(a_RDR, ah_RDR),(b_RDR, bh_RDR)] $
434 unliftedOrdOp tycon intPrimTy op ah_RDR bh_RDR
436 mkCompareFields :: TyCon -> OrdOp -> [Type] -> LHsExpr RdrName
437 -- Generates nested comparisons for (a1,a2...) against (b1,b2,...)
438 -- where the ai,bi have the given types
439 mkCompareFields tycon op tys
440 = go tys as_RDRs bs_RDRs
442 go [] _ _ = eqResult op
444 | isUnLiftedType ty = unliftedOrdOp tycon ty op a b
445 | otherwise = genOpApp (nlHsVar a) (ordMethRdr op) (nlHsVar b)
446 go (ty:tys) (a:as) (b:bs) = mk_compare ty a b
450 go _ _ _ = panic "mkCompareFields"
452 -- (mk_compare ty a b) generates
453 -- (case (compare a b) of { LT -> <lt>; EQ -> <eq>; GT -> <bt> })
454 -- but with suitable special cases for
455 mk_compare ty a b lt eq gt
457 = unliftedCompare lt_op eq_op a_expr b_expr lt eq gt
459 = nlHsCase (nlHsPar (nlHsApp (nlHsApp (nlHsVar compare_RDR) a_expr) b_expr))
460 [mkSimpleHsAlt (nlNullaryConPat ltTag_RDR) lt,
461 mkSimpleHsAlt (nlNullaryConPat eqTag_RDR) eq,
462 mkSimpleHsAlt (nlNullaryConPat gtTag_RDR) gt]
466 (lt_op, _, eq_op, _, _) = primOrdOps "Ord" tycon ty
468 unliftedOrdOp :: TyCon -> Type -> OrdOp -> RdrName -> RdrName -> LHsExpr RdrName
469 unliftedOrdOp tycon ty op a b
471 OrdCompare -> unliftedCompare lt_op eq_op a_expr b_expr
472 ltTag_Expr eqTag_Expr gtTag_Expr
478 (lt_op, le_op, eq_op, ge_op, gt_op) = primOrdOps "Ord" tycon ty
479 wrap prim_op = genOpApp a_expr (primOpRdrName prim_op) b_expr
483 unliftedCompare :: PrimOp -> PrimOp
484 -> LHsExpr RdrName -> LHsExpr RdrName -- What to cmpare
485 -> LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName -- Three results
487 -- Return (if a < b then lt else if a == b then eq else gt)
488 unliftedCompare lt_op eq_op a_expr b_expr lt eq gt
489 = nlHsIf (genOpApp a_expr (primOpRdrName lt_op) b_expr) lt $
490 -- Test (<) first, not (==), becuase the latter
491 -- is true less often, so putting it first would
492 -- mean more tests (dynamically)
493 nlHsIf (genOpApp a_expr (primOpRdrName eq_op) b_expr) eq gt
495 nlConWildPat :: DataCon -> LPat RdrName
496 -- The pattern (K {})
497 nlConWildPat con = noLoc (ConPatIn (noLoc (getRdrName con))
498 (RecCon (HsRecFields { rec_flds = []
499 , rec_dotdot = Nothing })))
504 %************************************************************************
508 %************************************************************************
510 @Enum@ can only be derived for enumeration types. For a type
512 data Foo ... = N1 | N2 | ... | Nn
515 we use both @con2tag_Foo@ and @tag2con_Foo@ functions, as well as a
516 @maxtag_Foo@ variable (all generated by @gen_tag_n_con_binds@).
519 instance ... Enum (Foo ...) where
520 succ x = toEnum (1 + fromEnum x)
521 pred x = toEnum (fromEnum x - 1)
523 toEnum i = tag2con_Foo i
525 enumFrom a = map tag2con_Foo [con2tag_Foo a .. maxtag_Foo]
529 = case con2tag_Foo a of
530 a# -> map tag2con_Foo (enumFromTo (I# a#) maxtag_Foo)
533 = map tag2con_Foo [con2tag_Foo a, con2tag_Foo b .. maxtag_Foo]
537 = case con2tag_Foo a of { a# ->
538 case con2tag_Foo b of { b# ->
539 map tag2con_Foo (enumFromThenTo (I# a#) (I# b#) maxtag_Foo)
543 For @enumFromTo@ and @enumFromThenTo@, we use the default methods.
546 gen_Enum_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
547 gen_Enum_binds loc tycon
548 = (method_binds, aux_binds)
550 method_binds = listToBag [
558 aux_binds = [GenCon2Tag tycon, GenTag2Con tycon, GenMaxTag tycon]
560 occ_nm = getOccString tycon
563 = mk_easy_FunBind loc succ_RDR [a_Pat] $
564 untag_Expr tycon [(a_RDR, ah_RDR)] $
565 nlHsIf (nlHsApps eq_RDR [nlHsVar (maxtag_RDR tycon),
566 nlHsVarApps intDataCon_RDR [ah_RDR]])
567 (illegal_Expr "succ" occ_nm "tried to take `succ' of last tag in enumeration")
568 (nlHsApp (nlHsVar (tag2con_RDR tycon))
569 (nlHsApps plus_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
573 = mk_easy_FunBind loc pred_RDR [a_Pat] $
574 untag_Expr tycon [(a_RDR, ah_RDR)] $
575 nlHsIf (nlHsApps eq_RDR [nlHsIntLit 0,
576 nlHsVarApps intDataCon_RDR [ah_RDR]])
577 (illegal_Expr "pred" occ_nm "tried to take `pred' of first tag in enumeration")
578 (nlHsApp (nlHsVar (tag2con_RDR tycon))
579 (nlHsApps plus_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
580 nlHsLit (HsInt (-1))]))
583 = mk_easy_FunBind loc toEnum_RDR [a_Pat] $
584 nlHsIf (nlHsApps and_RDR
585 [nlHsApps ge_RDR [nlHsVar a_RDR, nlHsIntLit 0],
586 nlHsApps le_RDR [nlHsVar a_RDR, nlHsVar (maxtag_RDR tycon)]])
587 (nlHsVarApps (tag2con_RDR tycon) [a_RDR])
588 (illegal_toEnum_tag occ_nm (maxtag_RDR tycon))
591 = mk_easy_FunBind loc enumFrom_RDR [a_Pat] $
592 untag_Expr tycon [(a_RDR, ah_RDR)] $
594 [nlHsVar (tag2con_RDR tycon),
595 nlHsPar (enum_from_to_Expr
596 (nlHsVarApps intDataCon_RDR [ah_RDR])
597 (nlHsVar (maxtag_RDR tycon)))]
600 = mk_easy_FunBind loc enumFromThen_RDR [a_Pat, b_Pat] $
601 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)] $
602 nlHsApp (nlHsVarApps map_RDR [tag2con_RDR tycon]) $
603 nlHsPar (enum_from_then_to_Expr
604 (nlHsVarApps intDataCon_RDR [ah_RDR])
605 (nlHsVarApps intDataCon_RDR [bh_RDR])
606 (nlHsIf (nlHsApps gt_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
607 nlHsVarApps intDataCon_RDR [bh_RDR]])
609 (nlHsVar (maxtag_RDR tycon))
613 = mk_easy_FunBind loc fromEnum_RDR [a_Pat] $
614 untag_Expr tycon [(a_RDR, ah_RDR)] $
615 (nlHsVarApps intDataCon_RDR [ah_RDR])
618 %************************************************************************
622 %************************************************************************
625 gen_Bounded_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
626 gen_Bounded_binds loc tycon
627 | isEnumerationTyCon tycon
628 = (listToBag [ min_bound_enum, max_bound_enum ], [])
630 = ASSERT(isSingleton data_cons)
631 (listToBag [ min_bound_1con, max_bound_1con ], [])
633 data_cons = tyConDataCons tycon
635 ----- enum-flavored: ---------------------------
636 min_bound_enum = mkHsVarBind loc minBound_RDR (nlHsVar data_con_1_RDR)
637 max_bound_enum = mkHsVarBind loc maxBound_RDR (nlHsVar data_con_N_RDR)
639 data_con_1 = head data_cons
640 data_con_N = last data_cons
641 data_con_1_RDR = getRdrName data_con_1
642 data_con_N_RDR = getRdrName data_con_N
644 ----- single-constructor-flavored: -------------
645 arity = dataConSourceArity data_con_1
647 min_bound_1con = mkHsVarBind loc minBound_RDR $
648 nlHsVarApps data_con_1_RDR (nOfThem arity minBound_RDR)
649 max_bound_1con = mkHsVarBind loc maxBound_RDR $
650 nlHsVarApps data_con_1_RDR (nOfThem arity maxBound_RDR)
653 %************************************************************************
657 %************************************************************************
659 Deriving @Ix@ is only possible for enumeration types and
660 single-constructor types. We deal with them in turn.
662 For an enumeration type, e.g.,
664 data Foo ... = N1 | N2 | ... | Nn
666 things go not too differently from @Enum@:
668 instance ... Ix (Foo ...) where
670 = map tag2con_Foo [con2tag_Foo a .. con2tag_Foo b]
674 = case (con2tag_Foo a) of { a# ->
675 case (con2tag_Foo b) of { b# ->
676 map tag2con_Foo (enumFromTo (I# a#) (I# b#))
679 -- Generate code for unsafeIndex, becuase using index leads
680 -- to lots of redundant range tests
681 unsafeIndex c@(a, b) d
682 = case (con2tag_Foo d -# con2tag_Foo a) of
687 p_tag = con2tag_Foo c
689 p_tag >= con2tag_Foo a && p_tag <= con2tag_Foo b
693 = case (con2tag_Foo a) of { a_tag ->
694 case (con2tag_Foo b) of { b_tag ->
695 case (con2tag_Foo c) of { c_tag ->
696 if (c_tag >=# a_tag) then
702 (modulo suitable case-ification to handle the unlifted tags)
704 For a single-constructor type (NB: this includes all tuples), e.g.,
706 data Foo ... = MkFoo a b Int Double c c
708 we follow the scheme given in Figure~19 of the Haskell~1.2 report
712 gen_Ix_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
714 gen_Ix_binds loc tycon
715 | isEnumerationTyCon tycon
716 = (enum_ixes, [GenCon2Tag tycon, GenTag2Con tycon, GenMaxTag tycon])
718 = (single_con_ixes, [GenCon2Tag tycon])
720 --------------------------------------------------------------
721 enum_ixes = listToBag [ enum_range, enum_index, enum_inRange ]
724 = mk_easy_FunBind loc range_RDR [nlTuplePat [a_Pat, b_Pat] Boxed] $
725 untag_Expr tycon [(a_RDR, ah_RDR)] $
726 untag_Expr tycon [(b_RDR, bh_RDR)] $
727 nlHsApp (nlHsVarApps map_RDR [tag2con_RDR tycon]) $
728 nlHsPar (enum_from_to_Expr
729 (nlHsVarApps intDataCon_RDR [ah_RDR])
730 (nlHsVarApps intDataCon_RDR [bh_RDR]))
733 = mk_easy_FunBind loc unsafeIndex_RDR
734 [noLoc (AsPat (noLoc c_RDR)
735 (nlTuplePat [a_Pat, nlWildPat] Boxed)),
737 untag_Expr tycon [(a_RDR, ah_RDR)] (
738 untag_Expr tycon [(d_RDR, dh_RDR)] (
740 rhs = nlHsVarApps intDataCon_RDR [c_RDR]
743 (genOpApp (nlHsVar dh_RDR) minusInt_RDR (nlHsVar ah_RDR))
744 [mkSimpleHsAlt (nlVarPat c_RDR) rhs]
749 = mk_easy_FunBind loc inRange_RDR [nlTuplePat [a_Pat, b_Pat] Boxed, c_Pat] $
750 untag_Expr tycon [(a_RDR, ah_RDR)] (
751 untag_Expr tycon [(b_RDR, bh_RDR)] (
752 untag_Expr tycon [(c_RDR, ch_RDR)] (
753 nlHsIf (genOpApp (nlHsVar ch_RDR) geInt_RDR (nlHsVar ah_RDR)) (
754 (genOpApp (nlHsVar ch_RDR) leInt_RDR (nlHsVar bh_RDR))
759 --------------------------------------------------------------
761 = listToBag [single_con_range, single_con_index, single_con_inRange]
764 = case tyConSingleDataCon_maybe tycon of -- just checking...
765 Nothing -> panic "get_Ix_binds"
768 con_arity = dataConSourceArity data_con
769 data_con_RDR = getRdrName data_con
771 as_needed = take con_arity as_RDRs
772 bs_needed = take con_arity bs_RDRs
773 cs_needed = take con_arity cs_RDRs
775 con_pat xs = nlConVarPat data_con_RDR xs
776 con_expr = nlHsVarApps data_con_RDR cs_needed
778 --------------------------------------------------------------
780 = mk_easy_FunBind loc range_RDR
781 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed] $
782 nlHsDo ListComp stmts con_expr
784 stmts = zipWith3Equal "single_con_range" mk_qual as_needed bs_needed cs_needed
786 mk_qual a b c = noLoc $ mkBindStmt (nlVarPat c)
787 (nlHsApp (nlHsVar range_RDR)
788 (mkLHsVarTuple [a,b]))
792 = mk_easy_FunBind loc unsafeIndex_RDR
793 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed,
795 -- We need to reverse the order we consider the components in
797 -- range (l,u) !! index (l,u) i == i -- when i is in range
798 -- (from http://haskell.org/onlinereport/ix.html) holds.
799 (mk_index (reverse $ zip3 as_needed bs_needed cs_needed))
801 -- index (l1,u1) i1 + rangeSize (l1,u1) * (index (l2,u2) i2 + ...)
802 mk_index [] = nlHsIntLit 0
803 mk_index [(l,u,i)] = mk_one l u i
804 mk_index ((l,u,i) : rest)
809 (nlHsApp (nlHsVar unsafeRangeSize_RDR)
810 (mkLHsVarTuple [l,u]))
811 ) times_RDR (mk_index rest)
814 = nlHsApps unsafeIndex_RDR [mkLHsVarTuple [l,u], nlHsVar i]
818 = mk_easy_FunBind loc inRange_RDR
819 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed,
821 foldl1 and_Expr (zipWith3Equal "single_con_inRange" in_range as_needed bs_needed cs_needed)
823 in_range a b c = nlHsApps inRange_RDR [mkLHsVarTuple [a,b], nlHsVar c]
826 %************************************************************************
830 %************************************************************************
840 instance Read T where
844 do x <- ReadP.step Read.readPrec
845 Symbol "%%" <- Lex.lex
846 y <- ReadP.step Read.readPrec
850 -- Note the "+1" part; "T2 T1 {f1=3}" should parse ok
851 -- Record construction binds even more tightly than application
852 do Ident "T1" <- Lex.lex
854 Ident "f1" <- Lex.lex
856 x <- ReadP.reset Read.readPrec
858 return (T1 { f1 = x }))
861 do Ident "T2" <- Lex.lexP
862 x <- ReadP.step Read.readPrec
866 readListPrec = readListPrecDefault
867 readList = readListDefault
871 gen_Read_binds :: FixityEnv -> SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
873 gen_Read_binds get_fixity loc tycon
874 = (listToBag [read_prec, default_readlist, default_readlistprec], [])
876 -----------------------------------------------------------------------
878 = mkHsVarBind loc readList_RDR (nlHsVar readListDefault_RDR)
881 = mkHsVarBind loc readListPrec_RDR (nlHsVar readListPrecDefault_RDR)
882 -----------------------------------------------------------------------
884 data_cons = tyConDataCons tycon
885 (nullary_cons, non_nullary_cons) = partition isNullarySrcDataCon data_cons
887 read_prec = mkHsVarBind loc readPrec_RDR
888 (nlHsApp (nlHsVar parens_RDR) read_cons)
890 read_cons = foldr1 mk_alt (read_nullary_cons ++ read_non_nullary_cons)
891 read_non_nullary_cons = map read_non_nullary_con non_nullary_cons
894 = case nullary_cons of
896 [con] -> [nlHsDo DoExpr [bindLex (match_con con)] (result_expr con [])]
897 _ -> [nlHsApp (nlHsVar choose_RDR)
898 (nlList (map mk_pair nullary_cons))]
899 -- NB For operators the parens around (:=:) are matched by the
900 -- enclosing "parens" call, so here we must match the naked
903 match_con con | isSym con_str = symbol_pat con_str
904 | otherwise = ident_pat con_str
906 con_str = data_con_str con
907 -- For nullary constructors we must match Ident s for normal constrs
908 -- and Symbol s for operators
910 mk_pair con = mkLHsTupleExpr [nlHsLit (mkHsString (data_con_str con)),
913 read_non_nullary_con data_con
914 | is_infix = mk_parser infix_prec infix_stmts body
915 | is_record = mk_parser record_prec record_stmts body
916 -- Using these two lines instead allows the derived
917 -- read for infix and record bindings to read the prefix form
918 -- | is_infix = mk_alt prefix_parser (mk_parser infix_prec infix_stmts body)
919 -- | is_record = mk_alt prefix_parser (mk_parser record_prec record_stmts body)
920 | otherwise = prefix_parser
922 body = result_expr data_con as_needed
923 con_str = data_con_str data_con
925 prefix_parser = mk_parser prefix_prec prefix_stmts body
928 | isSym con_str = [read_punc "(", bindLex (symbol_pat con_str), read_punc ")"]
929 | otherwise = [bindLex (ident_pat con_str)]
932 | isSym con_str = [bindLex (symbol_pat con_str)]
933 | otherwise = [read_punc "`", bindLex (ident_pat con_str), read_punc "`"]
935 prefix_stmts -- T a b c
936 = read_prefix_con ++ read_args
938 infix_stmts -- a %% b, or a `T` b
943 record_stmts -- T { f1 = a, f2 = b }
946 ++ concat (intersperse [read_punc ","] field_stmts)
949 field_stmts = zipWithEqual "lbl_stmts" read_field labels as_needed
951 con_arity = dataConSourceArity data_con
952 labels = dataConFieldLabels data_con
953 dc_nm = getName data_con
954 is_infix = dataConIsInfix data_con
955 is_record = length labels > 0
956 as_needed = take con_arity as_RDRs
957 read_args = zipWithEqual "gen_Read_binds" read_arg as_needed (dataConOrigArgTys data_con)
958 (read_a1:read_a2:_) = read_args
960 prefix_prec = appPrecedence
961 infix_prec = getPrecedence get_fixity dc_nm
962 record_prec = appPrecedence + 1 -- Record construction binds even more tightly
963 -- than application; e.g. T2 T1 {x=2} means T2 (T1 {x=2})
965 ------------------------------------------------------------------------
967 ------------------------------------------------------------------------
968 mk_alt e1 e2 = genOpApp e1 alt_RDR e2 -- e1 +++ e2
969 mk_parser p ss b = nlHsApps prec_RDR [nlHsIntLit p, nlHsDo DoExpr ss b] -- prec p (do { ss ; b })
970 bindLex pat = noLoc (mkBindStmt pat (nlHsVar lexP_RDR)) -- pat <- lexP
971 con_app con as = nlHsVarApps (getRdrName con) as -- con as
972 result_expr con as = nlHsApp (nlHsVar returnM_RDR) (con_app con as) -- return (con as)
974 punc_pat s = nlConPat punc_RDR [nlLitPat (mkHsString s)] -- Punc 'c'
975 ident_pat s = nlConPat ident_RDR [nlLitPat (mkHsString s)] -- Ident "foo"
976 symbol_pat s = nlConPat symbol_RDR [nlLitPat (mkHsString s)] -- Symbol ">>"
978 data_con_str con = occNameString (getOccName con)
980 read_punc c = bindLex (punc_pat c)
981 read_arg a ty = ASSERT( not (isUnLiftedType ty) )
982 noLoc (mkBindStmt (nlVarPat a) (nlHsVarApps step_RDR [readPrec_RDR]))
984 read_field lbl a = read_lbl lbl ++
986 noLoc (mkBindStmt (nlVarPat a) (nlHsVarApps reset_RDR [readPrec_RDR]))]
988 -- When reading field labels we might encounter
993 read_lbl lbl | isSym lbl_str
995 bindLex (symbol_pat lbl_str),
998 = [bindLex (ident_pat lbl_str)]
1000 lbl_str = occNameString (getOccName lbl)
1004 %************************************************************************
1008 %************************************************************************
1014 data Tree a = Leaf a | Tree a :^: Tree a
1016 instance (Show a) => Show (Tree a) where
1018 showsPrec d (Leaf m) = showParen (d > app_prec) showStr
1020 showStr = showString "Leaf " . showsPrec (app_prec+1) m
1022 showsPrec d (u :^: v) = showParen (d > up_prec) showStr
1024 showStr = showsPrec (up_prec+1) u .
1025 showString " :^: " .
1026 showsPrec (up_prec+1) v
1027 -- Note: right-associativity of :^: ignored
1029 up_prec = 5 -- Precedence of :^:
1030 app_prec = 10 -- Application has precedence one more than
1031 -- the most tightly-binding operator
1034 gen_Show_binds :: FixityEnv -> SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1036 gen_Show_binds get_fixity loc tycon
1037 = (listToBag [shows_prec, show_list], [])
1039 -----------------------------------------------------------------------
1040 show_list = mkHsVarBind loc showList_RDR
1041 (nlHsApp (nlHsVar showList___RDR) (nlHsPar (nlHsApp (nlHsVar showsPrec_RDR) (nlHsIntLit 0))))
1042 -----------------------------------------------------------------------
1043 data_cons = tyConDataCons tycon
1044 shows_prec = mk_FunBind loc showsPrec_RDR (map pats_etc data_cons)
1047 | nullary_con = -- skip the showParen junk...
1048 ASSERT(null bs_needed)
1049 ([nlWildPat, con_pat], mk_showString_app op_con_str)
1052 showParen_Expr (nlHsPar (genOpApp a_Expr ge_RDR (nlHsLit (HsInt con_prec_plus_one))))
1053 (nlHsPar (nested_compose_Expr show_thingies)))
1055 data_con_RDR = getRdrName data_con
1056 con_arity = dataConSourceArity data_con
1057 bs_needed = take con_arity bs_RDRs
1058 arg_tys = dataConOrigArgTys data_con -- Correspond 1-1 with bs_needed
1059 con_pat = nlConVarPat data_con_RDR bs_needed
1060 nullary_con = con_arity == 0
1061 labels = dataConFieldLabels data_con
1062 lab_fields = length labels
1063 record_syntax = lab_fields > 0
1065 dc_nm = getName data_con
1066 dc_occ_nm = getOccName data_con
1067 con_str = occNameString dc_occ_nm
1068 op_con_str = wrapOpParens con_str
1069 backquote_str = wrapOpBackquotes con_str
1072 | is_infix = [show_arg1, mk_showString_app (" " ++ backquote_str ++ " "), show_arg2]
1073 | record_syntax = mk_showString_app (op_con_str ++ " {") :
1074 show_record_args ++ [mk_showString_app "}"]
1075 | otherwise = mk_showString_app (op_con_str ++ " ") : show_prefix_args
1077 show_label l = mk_showString_app (nm ++ " = ")
1078 -- Note the spaces around the "=" sign. If we don't have them
1079 -- then we get Foo { x=-1 } and the "=-" parses as a single
1080 -- lexeme. Only the space after the '=' is necessary, but
1081 -- it seems tidier to have them both sides.
1083 occ_nm = getOccName l
1084 nm = wrapOpParens (occNameString occ_nm)
1086 show_args = zipWith show_arg bs_needed arg_tys
1087 (show_arg1:show_arg2:_) = show_args
1088 show_prefix_args = intersperse (nlHsVar showSpace_RDR) show_args
1090 -- Assumption for record syntax: no of fields == no of labelled fields
1091 -- (and in same order)
1092 show_record_args = concat $
1093 intersperse [mk_showString_app ", "] $
1094 [ [show_label lbl, arg]
1095 | (lbl,arg) <- zipEqual "gen_Show_binds"
1098 -- Generates (showsPrec p x) for argument x, but it also boxes
1099 -- the argument first if necessary. Note that this prints unboxed
1100 -- things without any '#' decorations; could change that if need be
1101 show_arg b arg_ty = nlHsApps showsPrec_RDR [nlHsLit (HsInt arg_prec),
1102 box_if_necy "Show" tycon (nlHsVar b) arg_ty]
1105 is_infix = dataConIsInfix data_con
1106 con_prec_plus_one = 1 + getPrec is_infix get_fixity dc_nm
1107 arg_prec | record_syntax = 0 -- Record fields don't need parens
1108 | otherwise = con_prec_plus_one
1110 wrapOpParens :: String -> String
1111 wrapOpParens s | isSym s = '(' : s ++ ")"
1114 wrapOpBackquotes :: String -> String
1115 wrapOpBackquotes s | isSym s = s
1116 | otherwise = '`' : s ++ "`"
1118 isSym :: String -> Bool
1120 isSym (c : _) = startsVarSym c || startsConSym c
1122 mk_showString_app :: String -> LHsExpr RdrName
1123 mk_showString_app str = nlHsApp (nlHsVar showString_RDR) (nlHsLit (mkHsString str))
1127 getPrec :: Bool -> FixityEnv -> Name -> Integer
1128 getPrec is_infix get_fixity nm
1129 | not is_infix = appPrecedence
1130 | otherwise = getPrecedence get_fixity nm
1132 appPrecedence :: Integer
1133 appPrecedence = fromIntegral maxPrecedence + 1
1134 -- One more than the precedence of the most
1135 -- tightly-binding operator
1137 getPrecedence :: FixityEnv -> Name -> Integer
1138 getPrecedence get_fixity nm
1139 = case lookupFixity get_fixity nm of
1140 Fixity x _assoc -> fromIntegral x
1141 -- NB: the Report says that associativity is not taken
1142 -- into account for either Read or Show; hence we
1143 -- ignore associativity here
1147 %************************************************************************
1149 \subsection{Typeable}
1151 %************************************************************************
1159 instance Typeable2 T where
1160 typeOf2 _ = mkTyConApp (mkTyConRep "T") []
1162 We are passed the Typeable2 class as well as T
1165 gen_Typeable_binds :: SrcSpan -> TyCon -> LHsBinds RdrName
1166 gen_Typeable_binds loc tycon
1169 (mk_typeOf_RDR tycon) -- Name of appropriate type0f function
1171 (nlHsApps mkTypeRep_RDR [tycon_rep, nlList []])
1173 tycon_rep = nlHsVar mkTyConRep_RDR `nlHsApp` nlHsLit (mkHsString (showSDocOneLine (ppr tycon)))
1175 mk_typeOf_RDR :: TyCon -> RdrName
1176 -- Use the arity of the TyCon to make the right typeOfn function
1177 mk_typeOf_RDR tycon = varQual_RDR tYPEABLE (mkFastString ("typeOf" ++ suffix))
1179 arity = tyConArity tycon
1180 suffix | arity == 0 = ""
1181 | otherwise = show arity
1186 %************************************************************************
1190 %************************************************************************
1194 data T a b = T1 a b | T2
1198 $cT1 = mkDataCon $dT "T1" Prefix
1199 $cT2 = mkDataCon $dT "T2" Prefix
1200 $dT = mkDataType "Module.T" [] [$con_T1, $con_T2]
1201 -- the [] is for field labels.
1203 instance (Data a, Data b) => Data (T a b) where
1204 gfoldl k z (T1 a b) = z T `k` a `k` b
1205 gfoldl k z T2 = z T2
1206 -- ToDo: add gmapT,Q,M, gfoldr
1208 gunfold k z c = case conIndex c of
1209 I# 1# -> k (k (z T1))
1212 toConstr (T1 _ _) = $cT1
1217 dataCast1 = gcast1 -- If T :: * -> *
1218 dataCast2 = gcast2 -- if T :: * -> * -> *
1222 gen_Data_binds :: SrcSpan
1224 -> (LHsBinds RdrName, -- The method bindings
1225 DerivAuxBinds) -- Auxiliary bindings
1226 gen_Data_binds loc tycon
1227 = (listToBag [gfoldl_bind, gunfold_bind, toCon_bind, dataTypeOf_bind]
1228 `unionBags` gcast_binds,
1229 -- Auxiliary definitions: the data type and constructors
1230 MkTyCon tycon : map MkDataCon data_cons)
1232 data_cons = tyConDataCons tycon
1233 n_cons = length data_cons
1234 one_constr = n_cons == 1
1237 gfoldl_bind = mk_FunBind loc gfoldl_RDR (map gfoldl_eqn data_cons)
1240 = ([nlVarPat k_RDR, nlVarPat z_RDR, nlConVarPat con_name as_needed],
1241 foldl mk_k_app (nlHsVar z_RDR `nlHsApp` nlHsVar con_name) as_needed)
1244 con_name = getRdrName con
1245 as_needed = take (dataConSourceArity con) as_RDRs
1246 mk_k_app e v = nlHsPar (nlHsOpApp e k_RDR (nlHsVar v))
1248 ------------ gunfold
1249 gunfold_bind = mk_FunBind loc
1251 [([k_Pat, z_Pat, if one_constr then nlWildPat else c_Pat],
1255 | one_constr = mk_unfold_rhs (head data_cons) -- No need for case
1256 | otherwise = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr)
1257 (map gunfold_alt data_cons)
1259 gunfold_alt dc = mkSimpleHsAlt (mk_unfold_pat dc) (mk_unfold_rhs dc)
1260 mk_unfold_rhs dc = foldr nlHsApp
1261 (nlHsVar z_RDR `nlHsApp` nlHsVar (getRdrName dc))
1262 (replicate (dataConSourceArity dc) (nlHsVar k_RDR))
1264 mk_unfold_pat dc -- Last one is a wild-pat, to avoid
1265 -- redundant test, and annoying warning
1266 | tag-fIRST_TAG == n_cons-1 = nlWildPat -- Last constructor
1267 | otherwise = nlConPat intDataCon_RDR [nlLitPat (HsIntPrim (toInteger tag))]
1271 ------------ toConstr
1272 toCon_bind = mk_FunBind loc toConstr_RDR (map to_con_eqn data_cons)
1273 to_con_eqn dc = ([nlWildConPat dc], nlHsVar (mk_constr_name dc))
1275 ------------ dataTypeOf
1276 dataTypeOf_bind = mk_easy_FunBind
1280 (nlHsVar (mk_data_type_name tycon))
1282 ------------ gcast1/2
1283 tycon_kind = tyConKind tycon
1284 gcast_binds | tycon_kind `eqKind` kind1 = mk_gcast dataCast1_RDR gcast1_RDR
1285 | tycon_kind `eqKind` kind2 = mk_gcast dataCast2_RDR gcast2_RDR
1286 | otherwise = emptyBag
1287 mk_gcast dataCast_RDR gcast_RDR
1288 = unitBag (mk_easy_FunBind loc dataCast_RDR [nlVarPat f_RDR]
1289 (nlHsVar gcast_RDR `nlHsApp` nlHsVar f_RDR))
1292 kind1, kind2 :: Kind
1293 kind1 = liftedTypeKind `mkArrowKind` liftedTypeKind
1294 kind2 = liftedTypeKind `mkArrowKind` kind1
1296 gfoldl_RDR, gunfold_RDR, toConstr_RDR, dataTypeOf_RDR, mkConstr_RDR,
1297 mkDataType_RDR, conIndex_RDR, prefix_RDR, infix_RDR,
1298 dataCast1_RDR, dataCast2_RDR, gcast1_RDR, gcast2_RDR,
1299 constr_RDR, dataType_RDR :: RdrName
1300 gfoldl_RDR = varQual_RDR gENERICS (fsLit "gfoldl")
1301 gunfold_RDR = varQual_RDR gENERICS (fsLit "gunfold")
1302 toConstr_RDR = varQual_RDR gENERICS (fsLit "toConstr")
1303 dataTypeOf_RDR = varQual_RDR gENERICS (fsLit "dataTypeOf")
1304 dataCast1_RDR = varQual_RDR gENERICS (fsLit "dataCast1")
1305 dataCast2_RDR = varQual_RDR gENERICS (fsLit "dataCast2")
1306 gcast1_RDR = varQual_RDR tYPEABLE (fsLit "gcast1")
1307 gcast2_RDR = varQual_RDR tYPEABLE (fsLit "gcast2")
1308 mkConstr_RDR = varQual_RDR gENERICS (fsLit "mkConstr")
1309 constr_RDR = tcQual_RDR gENERICS (fsLit "Constr")
1310 mkDataType_RDR = varQual_RDR gENERICS (fsLit "mkDataType")
1311 dataType_RDR = tcQual_RDR gENERICS (fsLit "DataType")
1312 conIndex_RDR = varQual_RDR gENERICS (fsLit "constrIndex")
1313 prefix_RDR = dataQual_RDR gENERICS (fsLit "Prefix")
1314 infix_RDR = dataQual_RDR gENERICS (fsLit "Infix")
1319 %************************************************************************
1323 see http://www.mail-archive.com/haskell-prime@haskell.org/msg02116.html
1326 %************************************************************************
1330 data T a = T1 Int a | T2 (T a)
1332 We generate the instance:
1334 instance Functor T where
1335 fmap f (T1 b1 a) = T1 b1 (f a)
1336 fmap f (T2 ta) = T2 (fmap f ta)
1338 Notice that we don't simply apply 'fmap' to the constructor arguments.
1340 - Do nothing to an argument whose type doesn't mention 'a'
1341 - Apply 'f' to an argument of type 'a'
1342 - Apply 'fmap f' to other arguments
1343 That's why we have to recurse deeply into the constructor argument types,
1344 rather than just one level, as we typically do.
1346 What about types with more than one type parameter? In general, we only
1347 derive Functor for the last position:
1349 data S a b = S1 [b] | S2 (a, T a b)
1350 instance Functor (S a) where
1351 fmap f (S1 bs) = S1 (fmap f bs)
1352 fmap f (S2 (p,q)) = S2 (a, fmap f q)
1354 However, we have special cases for
1358 More formally, we write the derivation of fmap code over type variable
1359 'a for type 'b as ($fmap 'a 'b). In this general notation the derived
1362 instance Functor T where
1363 fmap f (T1 x1 x2) = T1 ($(fmap 'a 'b1) x1) ($(fmap 'a 'a) x2)
1364 fmap f (T2 x1) = T2 ($(fmap 'a '(T a)) x1)
1366 $(fmap 'a 'b) x = x -- when b does not contain a
1367 $(fmap 'a 'a) x = f x
1368 $(fmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(fmap 'a 'b1) x1, $(fmap 'a 'b2) x2)
1369 $(fmap 'a '(T b1 b2)) x = fmap $(fmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1370 $(fmap 'a '(b -> c)) x = \b -> $(fmap 'a' 'c) (x ($(cofmap 'a 'b) b))
1372 For functions, the type parameter 'a can occur in a contravariant position,
1373 which means we need to derive a function like:
1375 cofmap :: (a -> b) -> (f b -> f a)
1377 This is pretty much the same as $fmap, only without the $(cofmap 'a 'a) case:
1379 $(cofmap 'a 'b) x = x -- when b does not contain a
1380 $(cofmap 'a 'a) x = error "type variable in contravariant position"
1381 $(cofmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(cofmap 'a 'b1) x1, $(cofmap 'a 'b2) x2)
1382 $(cofmap 'a '[b]) x = map $(cofmap 'a 'b) x
1383 $(cofmap 'a '(T b1 b2)) x = fmap $(cofmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1384 $(cofmap 'a '(b -> c)) x = \b -> $(cofmap 'a' 'c) (x ($(fmap 'a 'c) b))
1387 gen_Functor_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1388 gen_Functor_binds loc tycon
1389 = (unitBag fmap_bind, [])
1391 data_cons = tyConDataCons tycon
1392 fmap_bind = L loc $ mkRdrFunBind (L loc fmap_RDR) eqns
1394 fmap_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1396 parts = foldDataConArgs ft_fmap con
1398 eqns | null data_cons = [mkSimpleMatch [nlWildPat, nlWildPat]
1399 (error_Expr "Void fmap")]
1400 | otherwise = map fmap_eqn data_cons
1402 ft_fmap :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1403 -- Tricky higher order type; I can't say I fully understand this code :-(
1404 ft_fmap = FT { ft_triv = \x -> return x -- fmap f x = x
1405 , ft_var = \x -> return (nlHsApp f_Expr x) -- fmap f x = f x
1406 , ft_fun = \g h x -> mkSimpleLam (\b -> h =<< (nlHsApp x `fmap` g b))
1407 -- fmap f x = \b -> h (x (g b))
1408 , ft_tup = mkSimpleTupleCase match_for_con -- fmap f x = case x of (a1,a2,..) -> (g1 a1,g2 a2,..)
1409 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- fmap f x = fmap g x
1410 return $ nlHsApps fmap_RDR [gg,x]
1411 , ft_forall = \_ g x -> g x
1412 , ft_bad_app = panic "in other argument"
1413 , ft_co_var = panic "contravariant" }
1415 match_for_con = mkSimpleConMatch $
1416 \con_name xsM -> do xs <- sequence xsM
1417 return (nlHsApps con_name xs) -- Con (g1 v1) (g2 v2) ..
1420 Utility functions related to Functor deriving.
1422 Since several things use the same pattern of traversal, this is abstracted into functorLikeTraverse.
1423 This function works like a fold: it makes a value of type 'a' in a bottom up way.
1426 -- Generic traversal for Functor deriving
1427 data FFoldType a -- Describes how to fold over a Type in a functor like way
1428 = FT { ft_triv :: a -- Does not contain variable
1429 , ft_var :: a -- The variable itself
1430 , ft_co_var :: a -- The variable itself, contravariantly
1431 , ft_fun :: a -> a -> a -- Function type
1432 , ft_tup :: Boxity -> [a] -> a -- Tuple type
1433 , ft_ty_app :: Type -> a -> a -- Type app, variable only in last argument
1434 , ft_bad_app :: a -- Type app, variable other than in last argument
1435 , ft_forall :: TcTyVar -> a -> a -- Forall type
1438 functorLikeTraverse :: TyVar -- ^ Variable to look for
1439 -> FFoldType a -- ^ How to fold
1440 -> Type -- ^ Type to process
1442 functorLikeTraverse var (FT { ft_triv = caseTrivial, ft_var = caseVar
1443 , ft_co_var = caseCoVar, ft_fun = caseFun
1444 , ft_tup = caseTuple, ft_ty_app = caseTyApp
1445 , ft_bad_app = caseWrongArg, ft_forall = caseForAll })
1448 where -- go returns (result of type a, does type contain var)
1449 go co ty | Just ty' <- coreView ty = go co ty'
1450 go co (TyVarTy v) | v == var = (if co then caseCoVar else caseVar,True)
1451 go co (FunTy (PredTy _) b) = go co b
1452 go co (FunTy x y) | xc || yc = (caseFun xr yr,True)
1453 where (xr,xc) = go (not co) x
1455 go co (AppTy x y) | xc = (caseWrongArg, True)
1456 | yc = (caseTyApp x yr, True)
1457 where (_, xc) = go co x
1459 go co ty@(TyConApp con args)
1460 | not (or xcs) = (caseTrivial, False) -- Variable does not occur
1461 -- At this point we know that xrs, xcs is not empty,
1462 -- and at least one xr is True
1463 | isTupleTyCon con = (caseTuple (tupleTyConBoxity con) xrs, True)
1464 | or (init xcs) = (caseWrongArg, True) -- T (..var..) ty
1465 | otherwise = -- T (..no var..) ty
1466 (caseTyApp (fst (splitAppTy ty)) (last xrs), True)
1467 where (xrs,xcs) = unzip (map (go co) args)
1468 go co (ForAllTy v x) | v /= var && xc = (caseForAll v xr,True)
1469 where (xr,xc) = go co x
1470 go _ _ = (caseTrivial,False)
1472 -- Return all syntactic subterms of ty that contain var somewhere
1473 -- These are the things that should appear in instance constraints
1474 deepSubtypesContaining :: TyVar -> Type -> [TcType]
1475 deepSubtypesContaining tv
1476 = functorLikeTraverse tv
1479 , ft_fun = (++), ft_tup = \_ xs -> concat xs
1481 , ft_bad_app = panic "in other argument"
1482 , ft_co_var = panic "contravariant"
1483 , ft_forall = \v xs -> filterOut ((v `elemVarSet`) . tyVarsOfType) xs })
1486 foldDataConArgs :: FFoldType a -> DataCon -> [a]
1487 -- Fold over the arguments of the datacon
1488 foldDataConArgs ft con
1489 = map (functorLikeTraverse tv ft) (dataConOrigArgTys con)
1491 tv = last (dataConUnivTyVars con)
1492 -- Argument to derive for, 'a in the above description
1493 -- The validity checks have ensured that con is
1494 -- a vanilla data constructor
1496 -- Make a HsLam using a fresh variable from a State monad
1497 mkSimpleLam :: (LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1498 -- (mkSimpleLam fn) returns (\x. fn(x))
1499 mkSimpleLam lam = do
1502 body <- lam (nlHsVar n)
1503 return (mkHsLam [nlVarPat n] body)
1505 mkSimpleLam2 :: (LHsExpr id -> LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1506 mkSimpleLam2 lam = do
1507 (n1:n2:names) <- get
1509 body <- lam (nlHsVar n1) (nlHsVar n2)
1510 return (mkHsLam [nlVarPat n1,nlVarPat n2] body)
1512 -- "Con a1 a2 a3 -> fold [x1 a1, x2 a2, x3 a3]"
1513 mkSimpleConMatch :: Monad m => (RdrName -> [a] -> m (LHsExpr RdrName)) -> [LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName)
1514 mkSimpleConMatch fold extra_pats con insides = do
1515 let con_name = getRdrName con
1516 let vars_needed = takeList insides as_RDRs
1517 let pat = nlConVarPat con_name vars_needed
1518 rhs <- fold con_name (zipWith ($) insides (map nlHsVar vars_needed))
1519 return $ mkMatch (extra_pats ++ [pat]) rhs emptyLocalBinds
1521 -- "case x of (a1,a2,a3) -> fold [x1 a1, x2 a2, x3 a3]"
1522 mkSimpleTupleCase :: Monad m => ([LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName))
1523 -> Boxity -> [LHsExpr RdrName -> a] -> LHsExpr RdrName -> m (LHsExpr RdrName)
1524 mkSimpleTupleCase match_for_con boxity insides x = do
1525 let con = tupleCon boxity (length insides)
1526 match <- match_for_con [] con insides
1527 return $ nlHsCase x [match]
1531 %************************************************************************
1535 see http://www.mail-archive.com/haskell-prime@haskell.org/msg02116.html
1538 %************************************************************************
1540 Deriving Foldable instances works the same way as Functor instances,
1541 only Foldable instances are not possible for function types at all.
1542 Here the derived instance for the type T above is:
1544 instance Foldable T where
1545 foldr f z (T1 x1 x2 x3) = $(foldr 'a 'b1) x1 ( $(foldr 'a 'a) x2 ( $(foldr 'a 'b2) x3 z ) )
1549 $(foldr 'a 'b) x z = z -- when b does not contain a
1550 $(foldr 'a 'a) x z = f x z
1551 $(foldr 'a '(b1,b2)) x z = case x of (x1,x2) -> $(foldr 'a 'b1) x1 ( $(foldr 'a 'b2) x2 z )
1552 $(foldr 'a '(T b1 b2)) x z = foldr $(foldr 'a 'b2) x z -- when a only occurs in the last parameter, b2
1554 Note that the arguments to the real foldr function are the wrong way around,
1555 since (f :: a -> b -> b), while (foldr f :: b -> t a -> b).
1558 gen_Foldable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1559 gen_Foldable_binds loc tycon
1560 = (unitBag foldr_bind, [])
1562 data_cons = tyConDataCons tycon
1564 foldr_bind = L loc $ mkRdrFunBind (L loc foldable_foldr_RDR) eqns
1565 eqns = map foldr_eqn data_cons
1566 foldr_eqn con = evalState (match_for_con z_Expr [f_Pat,z_Pat] con parts) bs_RDRs
1568 parts = foldDataConArgs ft_foldr con
1570 ft_foldr :: FFoldType (LHsExpr RdrName -> LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1571 ft_foldr = FT { ft_triv = \_ z -> return z -- foldr f z x = z
1572 , ft_var = \x z -> return (nlHsApps f_RDR [x,z]) -- foldr f z x = f x z
1573 , ft_tup = \b gs x z -> mkSimpleTupleCase (match_for_con z) b gs x
1574 , ft_ty_app = \_ g x z -> do gg <- mkSimpleLam2 g -- foldr f z x = foldr (\xx zz -> g xx zz) z x
1575 return $ nlHsApps foldable_foldr_RDR [gg,z,x]
1576 , ft_forall = \_ g x z -> g x z
1577 , ft_co_var = panic "covariant"
1578 , ft_fun = panic "function"
1579 , ft_bad_app = panic "in other argument" }
1581 match_for_con z = mkSimpleConMatch (\_con_name -> foldrM ($) z) -- g1 v1 (g2 v2 (.. z))
1585 %************************************************************************
1587 Traversable instances
1589 see http://www.mail-archive.com/haskell-prime@haskell.org/msg02116.html
1591 %************************************************************************
1593 Again, Traversable is much like Functor and Foldable.
1597 $(traverse 'a 'b) x = pure x -- when b does not contain a
1598 $(traverse 'a 'a) x = f x
1599 $(traverse 'a '(b1,b2)) x = case x of (x1,x2) -> (,) <$> $(traverse 'a 'b1) x1 <*> $(traverse 'a 'b2) x2
1600 $(traverse 'a '(T b1 b2)) x = traverse $(traverse 'a 'b2) x -- when a only occurs in the last parameter, b2
1602 Note that the generated code is not as efficient as it could be. For instance:
1604 data T a = T Int a deriving Traversable
1606 gives the function: traverse f (T x y) = T <$> pure x <*> f y
1607 instead of: traverse f (T x y) = T x <$> f y
1610 gen_Traversable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1611 gen_Traversable_binds loc tycon
1612 = (unitBag traverse_bind, [])
1614 data_cons = tyConDataCons tycon
1616 traverse_bind = L loc $ mkRdrFunBind (L loc traverse_RDR) eqns
1617 eqns = map traverse_eqn data_cons
1618 traverse_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1620 parts = foldDataConArgs ft_trav con
1623 ft_trav :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1624 ft_trav = FT { ft_triv = \x -> return (nlHsApps pure_RDR [x]) -- traverse f x = pure x
1625 , ft_var = \x -> return (nlHsApps f_RDR [x]) -- travese f x = f x
1626 , ft_tup = mkSimpleTupleCase match_for_con -- travese f x z = case x of (a1,a2,..) ->
1627 -- (,,) <$> g1 a1 <*> g2 a2 <*> ..
1628 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- travese f x = travese (\xx -> g xx) x
1629 return $ nlHsApps traverse_RDR [gg,x]
1630 , ft_forall = \_ g x -> g x
1631 , ft_co_var = panic "covariant"
1632 , ft_fun = panic "function"
1633 , ft_bad_app = panic "in other argument" }
1635 match_for_con = mkSimpleConMatch $
1636 \con_name xsM -> do xs <- sequence xsM
1637 return (mkApCon (nlHsVar con_name) xs)
1639 -- ((Con <$> x1) <*> x2) <*> ..
1640 mkApCon con [] = nlHsApps pure_RDR [con]
1641 mkApCon con (x:xs) = foldl appAp (nlHsApps fmap_RDR [con,x]) xs
1642 where appAp x y = nlHsApps ap_RDR [x,y]
1647 %************************************************************************
1649 \subsection{Generating extra binds (@con2tag@ and @tag2con@)}
1651 %************************************************************************
1656 con2tag_Foo :: Foo ... -> Int#
1657 tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
1658 maxtag_Foo :: Int -- ditto (NB: not unlifted)
1661 The `tags' here start at zero, hence the @fIRST_TAG@ (currently one)
1665 genAuxBind :: SrcSpan -> DerivAuxBind -> (LHsBind RdrName, LSig RdrName)
1666 genAuxBind loc (GenCon2Tag tycon)
1667 = (mk_FunBind loc rdr_name eqns,
1668 L loc (TypeSig (L loc rdr_name) (L loc sig_ty)))
1670 rdr_name = con2tag_RDR tycon
1673 mkSigmaTy (tyConTyVars tycon) (tyConStupidTheta tycon) $
1674 mkParentType tycon `mkFunTy` intPrimTy
1676 lots_of_constructors = tyConFamilySize tycon > 8
1677 -- was: mAX_FAMILY_SIZE_FOR_VEC_RETURNS
1678 -- but we don't do vectored returns any more.
1680 eqns | lots_of_constructors = [get_tag_eqn]
1681 | otherwise = map mk_eqn (tyConDataCons tycon)
1683 get_tag_eqn = ([nlVarPat a_RDR], nlHsApp (nlHsVar getTag_RDR) a_Expr)
1685 mk_eqn :: DataCon -> ([LPat RdrName], LHsExpr RdrName)
1686 mk_eqn con = ([nlWildConPat con],
1687 nlHsLit (HsIntPrim (toInteger ((dataConTag con) - fIRST_TAG))))
1689 genAuxBind loc (GenTag2Con tycon)
1690 = (mk_FunBind loc rdr_name
1691 [([nlConVarPat intDataCon_RDR [a_RDR]],
1692 nlHsApp (nlHsVar tagToEnum_RDR) a_Expr)],
1693 L loc (TypeSig (L loc rdr_name) (L loc sig_ty)))
1695 sig_ty = HsCoreTy $ mkForAllTys (tyConTyVars tycon) $
1696 intTy `mkFunTy` mkParentType tycon
1698 rdr_name = tag2con_RDR tycon
1700 genAuxBind loc (GenMaxTag tycon)
1701 = (mkHsVarBind loc rdr_name rhs,
1702 L loc (TypeSig (L loc rdr_name) (L loc sig_ty)))
1704 rdr_name = maxtag_RDR tycon
1705 sig_ty = HsCoreTy intTy
1706 rhs = nlHsApp (nlHsVar intDataCon_RDR) (nlHsLit (HsIntPrim max_tag))
1707 max_tag = case (tyConDataCons tycon) of
1708 data_cons -> toInteger ((length data_cons) - fIRST_TAG)
1710 genAuxBind loc (MkTyCon tycon) -- $dT
1711 = (mkHsVarBind loc rdr_name rhs,
1712 L loc (TypeSig (L loc rdr_name) sig_ty))
1714 rdr_name = mk_data_type_name tycon
1715 sig_ty = nlHsTyVar dataType_RDR
1716 constrs = [nlHsVar (mk_constr_name con) | con <- tyConDataCons tycon]
1717 rhs = nlHsVar mkDataType_RDR
1718 `nlHsApp` nlHsLit (mkHsString (showSDocOneLine (ppr tycon)))
1719 `nlHsApp` nlList constrs
1721 genAuxBind loc (MkDataCon dc) -- $cT1 etc
1722 = (mkHsVarBind loc rdr_name rhs,
1723 L loc (TypeSig (L loc rdr_name) sig_ty))
1725 rdr_name = mk_constr_name dc
1726 sig_ty = nlHsTyVar constr_RDR
1727 rhs = nlHsApps mkConstr_RDR constr_args
1730 = [ -- nlHsIntLit (toInteger (dataConTag dc)), -- Tag
1731 nlHsVar (mk_data_type_name (dataConTyCon dc)), -- DataType
1732 nlHsLit (mkHsString (occNameString dc_occ)), -- String name
1733 nlList labels, -- Field labels
1734 nlHsVar fixity] -- Fixity
1736 labels = map (nlHsLit . mkHsString . getOccString)
1737 (dataConFieldLabels dc)
1738 dc_occ = getOccName dc
1739 is_infix = isDataSymOcc dc_occ
1740 fixity | is_infix = infix_RDR
1741 | otherwise = prefix_RDR
1743 mk_data_type_name :: TyCon -> RdrName -- "$tT"
1744 mk_data_type_name tycon = mkAuxBinderName (tyConName tycon) mkDataTOcc
1746 mk_constr_name :: DataCon -> RdrName -- "$cC"
1747 mk_constr_name con = mkAuxBinderName (dataConName con) mkDataCOcc
1749 mkParentType :: TyCon -> Type
1750 -- Turn the representation tycon of a family into
1751 -- a use of its family constructor
1753 = case tyConFamInst_maybe tc of
1754 Nothing -> mkTyConApp tc (mkTyVarTys (tyConTyVars tc))
1755 Just (fam_tc,tys) -> mkTyConApp fam_tc tys
1758 %************************************************************************
1760 \subsection{Utility bits for generating bindings}
1762 %************************************************************************
1766 mk_FunBind :: SrcSpan -> RdrName
1767 -> [([LPat RdrName], LHsExpr RdrName)]
1769 mk_FunBind loc fun pats_and_exprs
1770 = L loc $ mkRdrFunBind (L loc fun) matches
1772 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
1774 mkRdrFunBind :: Located RdrName -> [LMatch RdrName] -> HsBind RdrName
1775 mkRdrFunBind fun@(L _ fun_rdr) matches
1776 | null matches = mkFunBind fun [mkMatch [] (error_Expr str) emptyLocalBinds]
1777 -- Catch-all eqn looks like
1778 -- fmap = error "Void fmap"
1779 -- It's needed if there no data cons at all,
1780 -- which can happen with -XEmptyDataDecls
1782 | otherwise = mkFunBind fun matches
1784 str = "Void " ++ occNameString (rdrNameOcc fun_rdr)
1788 box_if_necy :: String -- The class involved
1789 -> TyCon -- The tycon involved
1790 -> LHsExpr RdrName -- The argument
1791 -> Type -- The argument type
1792 -> LHsExpr RdrName -- Boxed version of the arg
1793 box_if_necy cls_str tycon arg arg_ty
1794 | isUnLiftedType arg_ty = nlHsApp (nlHsVar box_con) arg
1797 box_con = assoc_ty_id cls_str tycon box_con_tbl arg_ty
1799 ---------------------
1800 primOrdOps :: String -- The class involved
1801 -> TyCon -- The tycon involved
1803 -> (PrimOp, PrimOp, PrimOp, PrimOp, PrimOp) -- (lt,le,eq,ge,gt)
1804 primOrdOps str tycon ty = assoc_ty_id str tycon ord_op_tbl ty
1806 ord_op_tbl :: [(Type, (PrimOp, PrimOp, PrimOp, PrimOp, PrimOp))]
1808 = [(charPrimTy, (CharLtOp, CharLeOp, CharEqOp, CharGeOp, CharGtOp))
1809 ,(intPrimTy, (IntLtOp, IntLeOp, IntEqOp, IntGeOp, IntGtOp))
1810 ,(wordPrimTy, (WordLtOp, WordLeOp, WordEqOp, WordGeOp, WordGtOp))
1811 ,(addrPrimTy, (AddrLtOp, AddrLeOp, AddrEqOp, AddrGeOp, AddrGtOp))
1812 ,(floatPrimTy, (FloatLtOp, FloatLeOp, FloatEqOp, FloatGeOp, FloatGtOp))
1813 ,(doublePrimTy, (DoubleLtOp, DoubleLeOp, DoubleEqOp, DoubleGeOp, DoubleGtOp)) ]
1815 box_con_tbl :: [(Type, RdrName)]
1817 [(charPrimTy, getRdrName charDataCon)
1818 ,(intPrimTy, getRdrName intDataCon)
1819 ,(wordPrimTy, wordDataCon_RDR)
1820 ,(floatPrimTy, getRdrName floatDataCon)
1821 ,(doublePrimTy, getRdrName doubleDataCon)
1824 assoc_ty_id :: String -- The class involved
1825 -> TyCon -- The tycon involved
1826 -> [(Type,a)] -- The table
1828 -> a -- The result of the lookup
1829 assoc_ty_id cls_str _ tbl ty
1830 | null res = pprPanic "Error in deriving:" (text "Can't derive" <+> text cls_str <+>
1831 text "for primitive type" <+> ppr ty)
1832 | otherwise = head res
1834 res = [id | (ty',id) <- tbl, ty `tcEqType` ty']
1836 -----------------------------------------------------------------------
1838 and_Expr :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1839 and_Expr a b = genOpApp a and_RDR b
1841 -----------------------------------------------------------------------
1843 eq_Expr :: TyCon -> Type -> LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1844 eq_Expr tycon ty a b = genOpApp a eq_op b
1846 eq_op | not (isUnLiftedType ty) = eq_RDR
1847 | otherwise = primOpRdrName prim_eq
1848 (_, _, prim_eq, _, _) = primOrdOps "Eq" tycon ty
1852 untag_Expr :: TyCon -> [( RdrName, RdrName)] -> LHsExpr RdrName -> LHsExpr RdrName
1853 untag_Expr _ [] expr = expr
1854 untag_Expr tycon ((untag_this, put_tag_here) : more) expr
1855 = nlHsCase (nlHsPar (nlHsVarApps (con2tag_RDR tycon) [untag_this])) {-of-}
1856 [mkSimpleHsAlt (nlVarPat put_tag_here) (untag_Expr tycon more expr)]
1859 :: LHsExpr RdrName -> LHsExpr RdrName
1861 enum_from_then_to_Expr
1862 :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1865 enum_from_to_Expr f t2 = nlHsApp (nlHsApp (nlHsVar enumFromTo_RDR) f) t2
1866 enum_from_then_to_Expr f t t2 = nlHsApp (nlHsApp (nlHsApp (nlHsVar enumFromThenTo_RDR) f) t) t2
1869 :: LHsExpr RdrName -> LHsExpr RdrName
1872 showParen_Expr e1 e2 = nlHsApp (nlHsApp (nlHsVar showParen_RDR) e1) e2
1874 nested_compose_Expr :: [LHsExpr RdrName] -> LHsExpr RdrName
1876 nested_compose_Expr [] = panic "nested_compose_expr" -- Arg is always non-empty
1877 nested_compose_Expr [e] = parenify e
1878 nested_compose_Expr (e:es)
1879 = nlHsApp (nlHsApp (nlHsVar compose_RDR) (parenify e)) (nested_compose_Expr es)
1881 -- impossible_Expr is used in case RHSs that should never happen.
1882 -- We generate these to keep the desugarer from complaining that they *might* happen!
1883 error_Expr :: String -> LHsExpr RdrName
1884 error_Expr string = nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString string))
1886 -- illegal_Expr is used when signalling error conditions in the RHS of a derived
1887 -- method. It is currently only used by Enum.{succ,pred}
1888 illegal_Expr :: String -> String -> String -> LHsExpr RdrName
1889 illegal_Expr meth tp msg =
1890 nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString (meth ++ '{':tp ++ "}: " ++ msg)))
1892 -- illegal_toEnum_tag is an extended version of illegal_Expr, which also allows you
1893 -- to include the value of a_RDR in the error string.
1894 illegal_toEnum_tag :: String -> RdrName -> LHsExpr RdrName
1895 illegal_toEnum_tag tp maxtag =
1896 nlHsApp (nlHsVar error_RDR)
1897 (nlHsApp (nlHsApp (nlHsVar append_RDR)
1898 (nlHsLit (mkHsString ("toEnum{" ++ tp ++ "}: tag ("))))
1899 (nlHsApp (nlHsApp (nlHsApp
1900 (nlHsVar showsPrec_RDR)
1904 (nlHsVar append_RDR)
1905 (nlHsLit (mkHsString ") is outside of enumeration's range (0,")))
1906 (nlHsApp (nlHsApp (nlHsApp
1907 (nlHsVar showsPrec_RDR)
1910 (nlHsLit (mkHsString ")"))))))
1912 parenify :: LHsExpr RdrName -> LHsExpr RdrName
1913 parenify e@(L _ (HsVar _)) = e
1914 parenify e = mkHsPar e
1916 -- genOpApp wraps brackets round the operator application, so that the
1917 -- renamer won't subsequently try to re-associate it.
1918 genOpApp :: LHsExpr RdrName -> RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1919 genOpApp e1 op e2 = nlHsPar (nlHsOpApp e1 op e2)
1923 a_RDR, b_RDR, c_RDR, d_RDR, f_RDR, k_RDR, z_RDR, ah_RDR, bh_RDR, ch_RDR, dh_RDR
1925 a_RDR = mkVarUnqual (fsLit "a")
1926 b_RDR = mkVarUnqual (fsLit "b")
1927 c_RDR = mkVarUnqual (fsLit "c")
1928 d_RDR = mkVarUnqual (fsLit "d")
1929 f_RDR = mkVarUnqual (fsLit "f")
1930 k_RDR = mkVarUnqual (fsLit "k")
1931 z_RDR = mkVarUnqual (fsLit "z")
1932 ah_RDR = mkVarUnqual (fsLit "a#")
1933 bh_RDR = mkVarUnqual (fsLit "b#")
1934 ch_RDR = mkVarUnqual (fsLit "c#")
1935 dh_RDR = mkVarUnqual (fsLit "d#")
1937 as_RDRs, bs_RDRs, cs_RDRs :: [RdrName]
1938 as_RDRs = [ mkVarUnqual (mkFastString ("a"++show i)) | i <- [(1::Int) .. ] ]
1939 bs_RDRs = [ mkVarUnqual (mkFastString ("b"++show i)) | i <- [(1::Int) .. ] ]
1940 cs_RDRs = [ mkVarUnqual (mkFastString ("c"++show i)) | i <- [(1::Int) .. ] ]
1942 a_Expr, c_Expr, f_Expr, z_Expr, ltTag_Expr, eqTag_Expr, gtTag_Expr,
1943 false_Expr, true_Expr :: LHsExpr RdrName
1944 a_Expr = nlHsVar a_RDR
1945 -- b_Expr = nlHsVar b_RDR
1946 c_Expr = nlHsVar c_RDR
1947 f_Expr = nlHsVar f_RDR
1948 z_Expr = nlHsVar z_RDR
1949 ltTag_Expr = nlHsVar ltTag_RDR
1950 eqTag_Expr = nlHsVar eqTag_RDR
1951 gtTag_Expr = nlHsVar gtTag_RDR
1952 false_Expr = nlHsVar false_RDR
1953 true_Expr = nlHsVar true_RDR
1955 a_Pat, b_Pat, c_Pat, d_Pat, f_Pat, k_Pat, z_Pat :: LPat RdrName
1956 a_Pat = nlVarPat a_RDR
1957 b_Pat = nlVarPat b_RDR
1958 c_Pat = nlVarPat c_RDR
1959 d_Pat = nlVarPat d_RDR
1960 f_Pat = nlVarPat f_RDR
1961 k_Pat = nlVarPat k_RDR
1962 z_Pat = nlVarPat z_RDR
1964 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon -> RdrName
1965 -- Generates Orig s RdrName, for the binding positions
1966 con2tag_RDR tycon = mk_tc_deriv_name tycon mkCon2TagOcc
1967 tag2con_RDR tycon = mk_tc_deriv_name tycon mkTag2ConOcc
1968 maxtag_RDR tycon = mk_tc_deriv_name tycon mkMaxTagOcc
1970 mk_tc_deriv_name :: TyCon -> (OccName -> OccName) -> RdrName
1971 mk_tc_deriv_name tycon occ_fun = mkAuxBinderName (tyConName tycon) occ_fun
1973 mkAuxBinderName :: Name -> (OccName -> OccName) -> RdrName
1974 mkAuxBinderName parent occ_fun = mkRdrUnqual (occ_fun (nameOccName parent))
1975 -- Was: mkDerivedRdrName name occ_fun, which made an original name
1976 -- But: (a) that does not work well for standalone-deriving
1977 -- (b) an unqualified name is just fine, provided it can't clash with user code
1980 s RdrName for PrimOps. Can't be done in PrelNames, because PrimOp imports
1981 PrelNames, so PrelNames can't import PrimOp.
1984 primOpRdrName :: PrimOp -> RdrName
1985 primOpRdrName op = getRdrName (primOpId op)
1987 minusInt_RDR, eqInt_RDR, ltInt_RDR, geInt_RDR, gtInt_RDR, leInt_RDR,
1988 tagToEnum_RDR :: RdrName
1989 minusInt_RDR = primOpRdrName IntSubOp
1990 eqInt_RDR = primOpRdrName IntEqOp
1991 ltInt_RDR = primOpRdrName IntLtOp
1992 geInt_RDR = primOpRdrName IntGeOp
1993 gtInt_RDR = primOpRdrName IntGtOp
1994 leInt_RDR = primOpRdrName IntLeOp
1995 tagToEnum_RDR = primOpRdrName TagToEnumOp
1997 error_RDR :: RdrName
1998 error_RDR = getRdrName eRROR_ID