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"
64 import Data.List ( partition, intersperse )
68 type DerivAuxBinds = [DerivAuxBind]
70 data DerivAuxBind -- Please add these auxiliary top-level bindings
71 = GenCon2Tag TyCon -- The con2Tag for given TyCon
72 | GenTag2Con TyCon -- ...ditto tag2Con
73 | GenMaxTag TyCon -- ...and maxTag
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 [
189 mk_FunBind loc eq_RDR ((map pats_etc nonnullary_cons) ++ rest),
190 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 For a derived @Ord@, we concentrate our attentions on @compare@
222 compare :: a -> a -> Ordering
223 data Ordering = LT | EQ | GT deriving ()
226 We will use the same example data type as above:
228 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
233 We do all the other @Ord@ methods with calls to @compare@:
235 instance ... (Ord <wurble> <wurble>) where
236 a < b = case (compare a b) of { LT -> True; EQ -> False; GT -> False }
237 a <= b = case (compare a b) of { LT -> True; EQ -> True; GT -> False }
238 a >= b = case (compare a b) of { LT -> False; EQ -> True; GT -> True }
239 a > b = case (compare a b) of { LT -> False; EQ -> False; GT -> True }
241 max a b = case (compare a b) of { LT -> b; EQ -> a; GT -> a }
242 min a b = case (compare a b) of { LT -> a; EQ -> b; GT -> b }
244 -- compare to come...
248 @compare@ always has two parts. First, we use the compared
249 data-constructors' tags to deal with the case of different
252 compare a b = case (con2tag_Foo a) of { a# ->
253 case (con2tag_Foo b) of { b# ->
254 case (a# ==# b#) of {
256 False -> case (a# <# b#) of
261 cmp_eq = ... to come ...
265 We are only left with the ``help'' function @cmp_eq@, to deal with
266 comparing data constructors with the same tag.
268 For the ordinary constructors (if any), we emit the sorta-obvious
269 compare-style stuff; for our example:
271 cmp_eq (O1 a1 b1) (O1 a2 b2)
272 = case (compare a1 a2) of { LT -> LT; EQ -> compare b1 b2; GT -> GT }
274 cmp_eq (O2 a1) (O2 a2)
277 cmp_eq (O3 a1 b1 c1) (O3 a2 b2 c2)
278 = case (compare a1 a2) of {
281 EQ -> case compare b1 b2 of {
289 Again, we must be careful about unlifted comparisons. For example,
290 if \tr{a1} and \tr{a2} were \tr{Int#}s in the 2nd example above, we'd need to
294 cmp_eq lt eq gt (O2 a1) (O2 a2)
296 -- or maybe the unfolded equivalent
300 For the remaining nullary constructors, we already know that the
307 If there is only one constructor in the Data Type we don't need the WildCard Pattern.
311 gen_Ord_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
313 gen_Ord_binds loc tycon
314 | Just (con, prim_tc) <- primWrapperType_maybe tycon
315 = gen_PrimOrd_binds con prim_tc
318 = (unitBag compare, aux_binds)
319 -- `AndMonoBinds` compare
320 -- The default declaration in PrelBase handles this
322 aux_binds | single_con_type = []
323 | otherwise = [GenCon2Tag tycon]
325 compare = L loc (mkFunBind (L loc compare_RDR) compare_matches)
326 compare_matches = [mkMatch [a_Pat, b_Pat] compare_rhs cmp_eq_binds]
327 cmp_eq_binds = HsValBinds (ValBindsIn (unitBag cmp_eq) [])
330 | single_con_type = cmp_eq_Expr a_Expr b_Expr
332 = untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)]
333 (cmp_tags_Expr eqInt_RDR ah_RDR bh_RDR
334 (cmp_eq_Expr a_Expr b_Expr) -- True case
335 -- False case; they aren't equal
336 -- So we need to do a less-than comparison on the tags
337 (cmp_tags_Expr ltInt_RDR ah_RDR bh_RDR ltTag_Expr gtTag_Expr))
339 tycon_data_cons = tyConDataCons tycon
340 single_con_type = isSingleton tycon_data_cons
341 (nullary_cons, nonnullary_cons)
342 | isNewTyCon tycon = ([], tyConDataCons tycon)
343 | otherwise = partition isNullarySrcDataCon tycon_data_cons
345 cmp_eq = mk_FunBind loc cmp_eq_RDR cmp_eq_match
347 | isEnumerationTyCon tycon
348 -- We know the tags are equal, so if it's an enumeration TyCon,
349 -- then there is nothing left to do
350 -- Catch this specially to avoid warnings
351 -- about overlapping patterns from the desugarer,
352 -- and to avoid unnecessary pattern-matching
353 = [([nlWildPat,nlWildPat], eqTag_Expr)]
355 = map pats_etc nonnullary_cons ++
356 (if single_con_type then -- Omit wildcards when there's just one
357 [] -- constructor, to silence desugarer
359 [([nlWildPat, nlWildPat], default_rhs)])
361 default_rhs | null nullary_cons = impossible_Expr -- Keep desugarer from complaining about
362 -- inexhaustive patterns
363 | otherwise = eqTag_Expr -- Some nullary constructors;
364 -- Tags are equal, no args => return EQ
366 = ([con1_pat, con2_pat],
367 nested_compare_expr tys_needed as_needed bs_needed)
369 con1_pat = nlConVarPat data_con_RDR as_needed
370 con2_pat = nlConVarPat data_con_RDR bs_needed
372 data_con_RDR = getRdrName data_con
373 con_arity = length tys_needed
374 as_needed = take con_arity as_RDRs
375 bs_needed = take con_arity bs_RDRs
376 tys_needed = dataConOrigArgTys data_con
378 nested_compare_expr [ty] [a] [b]
379 = careful_compare_Case tycon ty eqTag_Expr (nlHsVar a) (nlHsVar b)
381 nested_compare_expr (ty:tys) (a:as) (b:bs)
382 = let eq_expr = nested_compare_expr tys as bs
383 in careful_compare_Case tycon ty eq_expr (nlHsVar a) (nlHsVar b)
385 nested_compare_expr _ _ _ = panic "nested_compare_expr" -- Args always equal length
388 Note [Comparision of primitive types]
389 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
390 The general plan does not work well for data types like
391 data T = MkT Int# deriving( Ord )
392 The general plan defines the 'compare' method, gets (<) etc from it. But
393 that means we get silly code like:
395 (>) (I# x) (I# y) = case <# x y of
397 False -> case ==# x y of
400 We would prefer to use the (>#) primop. See also Trac #2130
404 gen_PrimOrd_binds :: DataCon -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
405 -- See Note [Comparison of primitive types]
406 gen_PrimOrd_binds data_con prim_tc
407 = (listToBag [mk_op lt_RDR lt_op, mk_op le_RDR le_op,
408 mk_op ge_RDR ge_op, mk_op gt_RDR gt_op], [])
410 mk_op op_RDR op = mk_FunBind (getSrcSpan data_con) op_RDR
411 [([apat, bpat], genOpApp a_Expr (primOpRdrName op) b_Expr)]
412 con_RDR = getRdrName data_con
413 apat = nlConVarPat con_RDR [a_RDR]
414 bpat = nlConVarPat con_RDR [b_RDR]
416 (lt_op, le_op, ge_op, gt_op)
417 | prim_tc == charPrimTyCon = (CharLtOp, CharLeOp, CharGeOp, CharGtOp)
418 | prim_tc == intPrimTyCon = (IntLtOp, IntLeOp, IntGeOp, IntGtOp)
419 | prim_tc == wordPrimTyCon = (WordLtOp, WordLeOp, WordGeOp, WordGtOp)
420 | prim_tc == addrPrimTyCon = (AddrLtOp, AddrLeOp, AddrGeOp, AddrGtOp)
421 | prim_tc == floatPrimTyCon = (FloatLtOp, FloatLeOp, FloatGeOp, FloatGtOp)
422 | prim_tc == doublePrimTyCon = (DoubleLtOp, DoubleLeOp, DoubleGeOp, DoubleGtOp)
423 | otherwise = pprPanic "Unexpected primitive tycon" (ppr prim_tc)
426 primWrapperType_maybe :: TyCon -> Maybe (DataCon, TyCon)
427 -- True of data types that are wrappers around prmitive types
428 -- data T = MkT Word#
429 -- For these we want to generate all the (<), (<=) etc operations individually
430 primWrapperType_maybe tc
431 | [con] <- tyConDataCons tc
432 , [ty] <- dataConOrigArgTys con
433 , Just (prim_tc, []) <- tcSplitTyConApp_maybe ty
434 , isPrimTyCon prim_tc
435 = Just (con, prim_tc)
440 %************************************************************************
444 %************************************************************************
446 @Enum@ can only be derived for enumeration types. For a type
448 data Foo ... = N1 | N2 | ... | Nn
451 we use both @con2tag_Foo@ and @tag2con_Foo@ functions, as well as a
452 @maxtag_Foo@ variable (all generated by @gen_tag_n_con_binds@).
455 instance ... Enum (Foo ...) where
456 succ x = toEnum (1 + fromEnum x)
457 pred x = toEnum (fromEnum x - 1)
459 toEnum i = tag2con_Foo i
461 enumFrom a = map tag2con_Foo [con2tag_Foo a .. maxtag_Foo]
465 = case con2tag_Foo a of
466 a# -> map tag2con_Foo (enumFromTo (I# a#) maxtag_Foo)
469 = map tag2con_Foo [con2tag_Foo a, con2tag_Foo b .. maxtag_Foo]
473 = case con2tag_Foo a of { a# ->
474 case con2tag_Foo b of { b# ->
475 map tag2con_Foo (enumFromThenTo (I# a#) (I# b#) maxtag_Foo)
479 For @enumFromTo@ and @enumFromThenTo@, we use the default methods.
482 gen_Enum_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
483 gen_Enum_binds loc tycon
484 = (method_binds, aux_binds)
486 method_binds = listToBag [
494 aux_binds = [GenCon2Tag tycon, GenTag2Con tycon, GenMaxTag tycon]
496 occ_nm = getOccString tycon
499 = mk_easy_FunBind loc succ_RDR [a_Pat] $
500 untag_Expr tycon [(a_RDR, ah_RDR)] $
501 nlHsIf (nlHsApps eq_RDR [nlHsVar (maxtag_RDR tycon),
502 nlHsVarApps intDataCon_RDR [ah_RDR]])
503 (illegal_Expr "succ" occ_nm "tried to take `succ' of last tag in enumeration")
504 (nlHsApp (nlHsVar (tag2con_RDR tycon))
505 (nlHsApps plus_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
509 = mk_easy_FunBind loc pred_RDR [a_Pat] $
510 untag_Expr tycon [(a_RDR, ah_RDR)] $
511 nlHsIf (nlHsApps eq_RDR [nlHsIntLit 0,
512 nlHsVarApps intDataCon_RDR [ah_RDR]])
513 (illegal_Expr "pred" occ_nm "tried to take `pred' of first tag in enumeration")
514 (nlHsApp (nlHsVar (tag2con_RDR tycon))
515 (nlHsApps plus_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
516 nlHsLit (HsInt (-1))]))
519 = mk_easy_FunBind loc toEnum_RDR [a_Pat] $
520 nlHsIf (nlHsApps and_RDR
521 [nlHsApps ge_RDR [nlHsVar a_RDR, nlHsIntLit 0],
522 nlHsApps le_RDR [nlHsVar a_RDR, nlHsVar (maxtag_RDR tycon)]])
523 (nlHsVarApps (tag2con_RDR tycon) [a_RDR])
524 (illegal_toEnum_tag occ_nm (maxtag_RDR tycon))
527 = mk_easy_FunBind loc enumFrom_RDR [a_Pat] $
528 untag_Expr tycon [(a_RDR, ah_RDR)] $
530 [nlHsVar (tag2con_RDR tycon),
531 nlHsPar (enum_from_to_Expr
532 (nlHsVarApps intDataCon_RDR [ah_RDR])
533 (nlHsVar (maxtag_RDR tycon)))]
536 = mk_easy_FunBind loc enumFromThen_RDR [a_Pat, b_Pat] $
537 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)] $
538 nlHsApp (nlHsVarApps map_RDR [tag2con_RDR tycon]) $
539 nlHsPar (enum_from_then_to_Expr
540 (nlHsVarApps intDataCon_RDR [ah_RDR])
541 (nlHsVarApps intDataCon_RDR [bh_RDR])
542 (nlHsIf (nlHsApps gt_RDR [nlHsVarApps intDataCon_RDR [ah_RDR],
543 nlHsVarApps intDataCon_RDR [bh_RDR]])
545 (nlHsVar (maxtag_RDR tycon))
549 = mk_easy_FunBind loc fromEnum_RDR [a_Pat] $
550 untag_Expr tycon [(a_RDR, ah_RDR)] $
551 (nlHsVarApps intDataCon_RDR [ah_RDR])
554 %************************************************************************
558 %************************************************************************
561 gen_Bounded_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
562 gen_Bounded_binds loc tycon
563 | isEnumerationTyCon tycon
564 = (listToBag [ min_bound_enum, max_bound_enum ], [])
566 = ASSERT(isSingleton data_cons)
567 (listToBag [ min_bound_1con, max_bound_1con ], [])
569 data_cons = tyConDataCons tycon
571 ----- enum-flavored: ---------------------------
572 min_bound_enum = mkVarBind loc minBound_RDR (nlHsVar data_con_1_RDR)
573 max_bound_enum = mkVarBind loc maxBound_RDR (nlHsVar data_con_N_RDR)
575 data_con_1 = head data_cons
576 data_con_N = last data_cons
577 data_con_1_RDR = getRdrName data_con_1
578 data_con_N_RDR = getRdrName data_con_N
580 ----- single-constructor-flavored: -------------
581 arity = dataConSourceArity data_con_1
583 min_bound_1con = mkVarBind loc minBound_RDR $
584 nlHsVarApps data_con_1_RDR (nOfThem arity minBound_RDR)
585 max_bound_1con = mkVarBind loc maxBound_RDR $
586 nlHsVarApps data_con_1_RDR (nOfThem arity maxBound_RDR)
589 %************************************************************************
593 %************************************************************************
595 Deriving @Ix@ is only possible for enumeration types and
596 single-constructor types. We deal with them in turn.
598 For an enumeration type, e.g.,
600 data Foo ... = N1 | N2 | ... | Nn
602 things go not too differently from @Enum@:
604 instance ... Ix (Foo ...) where
606 = map tag2con_Foo [con2tag_Foo a .. con2tag_Foo b]
610 = case (con2tag_Foo a) of { a# ->
611 case (con2tag_Foo b) of { b# ->
612 map tag2con_Foo (enumFromTo (I# a#) (I# b#))
615 -- Generate code for unsafeIndex, becuase using index leads
616 -- to lots of redundant range tests
617 unsafeIndex c@(a, b) d
618 = case (con2tag_Foo d -# con2tag_Foo a) of
623 p_tag = con2tag_Foo c
625 p_tag >= con2tag_Foo a && p_tag <= con2tag_Foo b
629 = case (con2tag_Foo a) of { a_tag ->
630 case (con2tag_Foo b) of { b_tag ->
631 case (con2tag_Foo c) of { c_tag ->
632 if (c_tag >=# a_tag) then
638 (modulo suitable case-ification to handle the unlifted tags)
640 For a single-constructor type (NB: this includes all tuples), e.g.,
642 data Foo ... = MkFoo a b Int Double c c
644 we follow the scheme given in Figure~19 of the Haskell~1.2 report
648 gen_Ix_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
650 gen_Ix_binds loc tycon
651 | isEnumerationTyCon tycon
652 = (enum_ixes, [GenCon2Tag tycon, GenTag2Con tycon, GenMaxTag tycon])
654 = (single_con_ixes, [GenCon2Tag tycon])
656 --------------------------------------------------------------
657 enum_ixes = listToBag [ enum_range, enum_index, enum_inRange ]
660 = mk_easy_FunBind loc range_RDR [nlTuplePat [a_Pat, b_Pat] Boxed] $
661 untag_Expr tycon [(a_RDR, ah_RDR)] $
662 untag_Expr tycon [(b_RDR, bh_RDR)] $
663 nlHsApp (nlHsVarApps map_RDR [tag2con_RDR tycon]) $
664 nlHsPar (enum_from_to_Expr
665 (nlHsVarApps intDataCon_RDR [ah_RDR])
666 (nlHsVarApps intDataCon_RDR [bh_RDR]))
669 = mk_easy_FunBind loc unsafeIndex_RDR
670 [noLoc (AsPat (noLoc c_RDR)
671 (nlTuplePat [a_Pat, nlWildPat] Boxed)),
673 untag_Expr tycon [(a_RDR, ah_RDR)] (
674 untag_Expr tycon [(d_RDR, dh_RDR)] (
676 rhs = nlHsVarApps intDataCon_RDR [c_RDR]
679 (genOpApp (nlHsVar dh_RDR) minusInt_RDR (nlHsVar ah_RDR))
680 [mkSimpleHsAlt (nlVarPat c_RDR) rhs]
685 = mk_easy_FunBind loc inRange_RDR [nlTuplePat [a_Pat, b_Pat] Boxed, c_Pat] $
686 untag_Expr tycon [(a_RDR, ah_RDR)] (
687 untag_Expr tycon [(b_RDR, bh_RDR)] (
688 untag_Expr tycon [(c_RDR, ch_RDR)] (
689 nlHsIf (genOpApp (nlHsVar ch_RDR) geInt_RDR (nlHsVar ah_RDR)) (
690 (genOpApp (nlHsVar ch_RDR) leInt_RDR (nlHsVar bh_RDR))
695 --------------------------------------------------------------
697 = listToBag [single_con_range, single_con_index, single_con_inRange]
700 = case tyConSingleDataCon_maybe tycon of -- just checking...
701 Nothing -> panic "get_Ix_binds"
704 con_arity = dataConSourceArity data_con
705 data_con_RDR = getRdrName data_con
707 as_needed = take con_arity as_RDRs
708 bs_needed = take con_arity bs_RDRs
709 cs_needed = take con_arity cs_RDRs
711 con_pat xs = nlConVarPat data_con_RDR xs
712 con_expr = nlHsVarApps data_con_RDR cs_needed
714 --------------------------------------------------------------
716 = mk_easy_FunBind loc range_RDR
717 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed] $
718 nlHsDo ListComp stmts con_expr
720 stmts = zipWith3Equal "single_con_range" mk_qual as_needed bs_needed cs_needed
722 mk_qual a b c = noLoc $ mkBindStmt (nlVarPat c)
723 (nlHsApp (nlHsVar range_RDR)
724 (nlTuple [nlHsVar a, nlHsVar b] Boxed))
728 = mk_easy_FunBind loc unsafeIndex_RDR
729 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed,
731 -- We need to reverse the order we consider the components in
733 -- range (l,u) !! index (l,u) i == i -- when i is in range
734 -- (from http://haskell.org/onlinereport/ix.html) holds.
735 (mk_index (reverse $ zip3 as_needed bs_needed cs_needed))
737 -- index (l1,u1) i1 + rangeSize (l1,u1) * (index (l2,u2) i2 + ...)
738 mk_index [] = nlHsIntLit 0
739 mk_index [(l,u,i)] = mk_one l u i
740 mk_index ((l,u,i) : rest)
745 (nlHsApp (nlHsVar unsafeRangeSize_RDR)
746 (nlTuple [nlHsVar l, nlHsVar u] Boxed))
747 ) times_RDR (mk_index rest)
750 = nlHsApps unsafeIndex_RDR [nlTuple [nlHsVar l, nlHsVar u] Boxed, nlHsVar i]
754 = mk_easy_FunBind loc inRange_RDR
755 [nlTuplePat [con_pat as_needed, con_pat bs_needed] Boxed,
757 foldl1 and_Expr (zipWith3Equal "single_con_inRange" in_range as_needed bs_needed cs_needed)
759 in_range a b c = nlHsApps inRange_RDR [nlTuple [nlHsVar a, nlHsVar b] Boxed,
763 %************************************************************************
767 %************************************************************************
777 instance Read T where
781 do x <- ReadP.step Read.readPrec
782 Symbol "%%" <- Lex.lex
783 y <- ReadP.step Read.readPrec
787 -- Note the "+1" part; "T2 T1 {f1=3}" should parse ok
788 -- Record construction binds even more tightly than application
789 do Ident "T1" <- Lex.lex
791 Ident "f1" <- Lex.lex
793 x <- ReadP.reset Read.readPrec
795 return (T1 { f1 = x }))
798 do Ident "T2" <- Lex.lexP
799 x <- ReadP.step Read.readPrec
803 readListPrec = readListPrecDefault
804 readList = readListDefault
808 gen_Read_binds :: FixityEnv -> SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
810 gen_Read_binds get_fixity loc tycon
811 = (listToBag [read_prec, default_readlist, default_readlistprec], [])
813 -----------------------------------------------------------------------
815 = mkVarBind loc readList_RDR (nlHsVar readListDefault_RDR)
818 = mkVarBind loc readListPrec_RDR (nlHsVar readListPrecDefault_RDR)
819 -----------------------------------------------------------------------
821 data_cons = tyConDataCons tycon
822 (nullary_cons, non_nullary_cons) = partition isNullarySrcDataCon data_cons
824 read_prec = mkVarBind loc readPrec_RDR
825 (nlHsApp (nlHsVar parens_RDR) read_cons)
827 read_cons = foldr1 mk_alt (read_nullary_cons ++ read_non_nullary_cons)
828 read_non_nullary_cons = map read_non_nullary_con non_nullary_cons
831 = case nullary_cons of
833 [con] -> [nlHsDo DoExpr [bindLex (ident_pat (data_con_str con))]
834 (result_expr con [])]
835 _ -> [nlHsApp (nlHsVar choose_RDR)
836 (nlList (map mk_pair nullary_cons))]
838 mk_pair con = nlTuple [nlHsLit (mkHsString (data_con_str con)),
842 read_non_nullary_con data_con
843 | is_infix = mk_parser infix_prec infix_stmts body
844 | is_record = mk_parser record_prec record_stmts body
845 -- Using these two lines instead allows the derived
846 -- read for infix and record bindings to read the prefix form
847 -- | is_infix = mk_alt prefix_parser (mk_parser infix_prec infix_stmts body)
848 -- | is_record = mk_alt prefix_parser (mk_parser record_prec record_stmts body)
849 | otherwise = prefix_parser
851 body = result_expr data_con as_needed
852 con_str = data_con_str data_con
854 prefix_parser = mk_parser prefix_prec prefix_stmts body
857 | isSym con_str = [read_punc "(", bindLex (symbol_pat con_str), read_punc ")"]
858 | otherwise = [bindLex (ident_pat con_str)]
861 | isSym con_str = [bindLex (symbol_pat con_str)]
862 | otherwise = [read_punc "`", bindLex (ident_pat con_str), read_punc "`"]
864 prefix_stmts -- T a b c
865 = read_prefix_con ++ read_args
867 infix_stmts -- a %% b, or a `T` b
872 record_stmts -- T { f1 = a, f2 = b }
875 ++ concat (intersperse [read_punc ","] field_stmts)
878 field_stmts = zipWithEqual "lbl_stmts" read_field labels as_needed
880 con_arity = dataConSourceArity data_con
881 labels = dataConFieldLabels data_con
882 dc_nm = getName data_con
883 is_infix = dataConIsInfix data_con
884 is_record = length labels > 0
885 as_needed = take con_arity as_RDRs
886 read_args = zipWithEqual "gen_Read_binds" read_arg as_needed (dataConOrigArgTys data_con)
887 (read_a1:read_a2:_) = read_args
889 prefix_prec = appPrecedence
890 infix_prec = getPrecedence get_fixity dc_nm
891 record_prec = appPrecedence + 1 -- Record construction binds even more tightly
892 -- than application; e.g. T2 T1 {x=2} means T2 (T1 {x=2})
894 ------------------------------------------------------------------------
896 ------------------------------------------------------------------------
897 mk_alt e1 e2 = genOpApp e1 alt_RDR e2 -- e1 +++ e2
898 mk_parser p ss b = nlHsApps prec_RDR [nlHsIntLit p, nlHsDo DoExpr ss b] -- prec p (do { ss ; b })
899 bindLex pat = noLoc (mkBindStmt pat (nlHsVar lexP_RDR)) -- pat <- lexP
900 con_app con as = nlHsVarApps (getRdrName con) as -- con as
901 result_expr con as = nlHsApp (nlHsVar returnM_RDR) (con_app con as) -- return (con as)
903 punc_pat s = nlConPat punc_RDR [nlLitPat (mkHsString s)] -- Punc 'c'
904 ident_pat s = nlConPat ident_RDR [nlLitPat (mkHsString s)] -- Ident "foo"
905 symbol_pat s = nlConPat symbol_RDR [nlLitPat (mkHsString s)] -- Symbol ">>"
907 data_con_str con = occNameString (getOccName con)
909 read_punc c = bindLex (punc_pat c)
910 read_arg a ty = ASSERT( not (isUnLiftedType ty) )
911 noLoc (mkBindStmt (nlVarPat a) (nlHsVarApps step_RDR [readPrec_RDR]))
913 read_field lbl a = read_lbl lbl ++
915 noLoc (mkBindStmt (nlVarPat a) (nlHsVarApps reset_RDR [readPrec_RDR]))]
917 -- When reading field labels we might encounter
922 read_lbl lbl | isSym lbl_str
924 bindLex (symbol_pat lbl_str),
927 = [bindLex (ident_pat lbl_str)]
929 lbl_str = occNameString (getOccName lbl)
933 %************************************************************************
937 %************************************************************************
943 data Tree a = Leaf a | Tree a :^: Tree a
945 instance (Show a) => Show (Tree a) where
947 showsPrec d (Leaf m) = showParen (d > app_prec) showStr
949 showStr = showString "Leaf " . showsPrec (app_prec+1) m
951 showsPrec d (u :^: v) = showParen (d > up_prec) showStr
953 showStr = showsPrec (up_prec+1) u .
955 showsPrec (up_prec+1) v
956 -- Note: right-associativity of :^: ignored
958 up_prec = 5 -- Precedence of :^:
959 app_prec = 10 -- Application has precedence one more than
960 -- the most tightly-binding operator
963 gen_Show_binds :: FixityEnv -> SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
965 gen_Show_binds get_fixity loc tycon
966 = (listToBag [shows_prec, show_list], [])
968 -----------------------------------------------------------------------
969 show_list = mkVarBind loc showList_RDR
970 (nlHsApp (nlHsVar showList___RDR) (nlHsPar (nlHsApp (nlHsVar showsPrec_RDR) (nlHsIntLit 0))))
971 -----------------------------------------------------------------------
972 shows_prec = mk_FunBind loc showsPrec_RDR (map pats_etc (tyConDataCons tycon))
975 | nullary_con = -- skip the showParen junk...
976 ASSERT(null bs_needed)
977 ([nlWildPat, con_pat], mk_showString_app con_str)
980 showParen_Expr (nlHsPar (genOpApp a_Expr ge_RDR (nlHsLit (HsInt con_prec_plus_one))))
981 (nlHsPar (nested_compose_Expr show_thingies)))
983 data_con_RDR = getRdrName data_con
984 con_arity = dataConSourceArity data_con
985 bs_needed = take con_arity bs_RDRs
986 arg_tys = dataConOrigArgTys data_con -- Correspond 1-1 with bs_needed
987 con_pat = nlConVarPat data_con_RDR bs_needed
988 nullary_con = con_arity == 0
989 labels = dataConFieldLabels data_con
990 lab_fields = length labels
991 record_syntax = lab_fields > 0
993 dc_nm = getName data_con
994 dc_occ_nm = getOccName data_con
995 con_str = occNameString dc_occ_nm
996 op_con_str = wrapOpParens con_str
997 backquote_str = wrapOpBackquotes con_str
1000 | is_infix = [show_arg1, mk_showString_app (" " ++ backquote_str ++ " "), show_arg2]
1001 | record_syntax = mk_showString_app (op_con_str ++ " {") :
1002 show_record_args ++ [mk_showString_app "}"]
1003 | otherwise = mk_showString_app (op_con_str ++ " ") : show_prefix_args
1005 show_label l = mk_showString_app (nm ++ " = ")
1006 -- Note the spaces around the "=" sign. If we don't have them
1007 -- then we get Foo { x=-1 } and the "=-" parses as a single
1008 -- lexeme. Only the space after the '=' is necessary, but
1009 -- it seems tidier to have them both sides.
1011 occ_nm = getOccName l
1012 nm = wrapOpParens (occNameString occ_nm)
1014 show_args = zipWith show_arg bs_needed arg_tys
1015 (show_arg1:show_arg2:_) = show_args
1016 show_prefix_args = intersperse (nlHsVar showSpace_RDR) show_args
1018 -- Assumption for record syntax: no of fields == no of labelled fields
1019 -- (and in same order)
1020 show_record_args = concat $
1021 intersperse [mk_showString_app ", "] $
1022 [ [show_label lbl, arg]
1023 | (lbl,arg) <- zipEqual "gen_Show_binds"
1026 -- Generates (showsPrec p x) for argument x, but it also boxes
1027 -- the argument first if necessary. Note that this prints unboxed
1028 -- things without any '#' decorations; could change that if need be
1029 show_arg b arg_ty = nlHsApps showsPrec_RDR [nlHsLit (HsInt arg_prec),
1030 box_if_necy "Show" tycon (nlHsVar b) arg_ty]
1033 is_infix = dataConIsInfix data_con
1034 con_prec_plus_one = 1 + getPrec is_infix get_fixity dc_nm
1035 arg_prec | record_syntax = 0 -- Record fields don't need parens
1036 | otherwise = con_prec_plus_one
1038 wrapOpParens :: String -> String
1039 wrapOpParens s | isSym s = '(' : s ++ ")"
1042 wrapOpBackquotes :: String -> String
1043 wrapOpBackquotes s | isSym s = s
1044 | otherwise = '`' : s ++ "`"
1046 isSym :: String -> Bool
1048 isSym (c : _) = startsVarSym c || startsConSym c
1050 mk_showString_app :: String -> LHsExpr RdrName
1051 mk_showString_app str = nlHsApp (nlHsVar showString_RDR) (nlHsLit (mkHsString str))
1055 getPrec :: Bool -> FixityEnv -> Name -> Integer
1056 getPrec is_infix get_fixity nm
1057 | not is_infix = appPrecedence
1058 | otherwise = getPrecedence get_fixity nm
1060 appPrecedence :: Integer
1061 appPrecedence = fromIntegral maxPrecedence + 1
1062 -- One more than the precedence of the most
1063 -- tightly-binding operator
1065 getPrecedence :: FixityEnv -> Name -> Integer
1066 getPrecedence get_fixity nm
1067 = case lookupFixity get_fixity nm of
1068 Fixity x _assoc -> fromIntegral x
1069 -- NB: the Report says that associativity is not taken
1070 -- into account for either Read or Show; hence we
1071 -- ignore associativity here
1075 %************************************************************************
1077 \subsection{Typeable}
1079 %************************************************************************
1087 instance Typeable2 T where
1088 typeOf2 _ = mkTyConApp (mkTyConRep "T") []
1090 We are passed the Typeable2 class as well as T
1093 gen_Typeable_binds :: SrcSpan -> TyCon -> LHsBinds RdrName
1094 gen_Typeable_binds loc tycon
1097 (mk_typeOf_RDR tycon) -- Name of appropriate type0f function
1099 (nlHsApps mkTypeRep_RDR [tycon_rep, nlList []])
1101 tycon_rep = nlHsVar mkTyConRep_RDR `nlHsApp` nlHsLit (mkHsString (showSDocOneLine (ppr tycon)))
1103 mk_typeOf_RDR :: TyCon -> RdrName
1104 -- Use the arity of the TyCon to make the right typeOfn function
1105 mk_typeOf_RDR tycon = varQual_RDR tYPEABLE (mkFastString ("typeOf" ++ suffix))
1107 arity = tyConArity tycon
1108 suffix | arity == 0 = ""
1109 | otherwise = show arity
1114 %************************************************************************
1118 %************************************************************************
1122 data T a b = T1 a b | T2
1126 $cT1 = mkDataCon $dT "T1" Prefix
1127 $cT2 = mkDataCon $dT "T2" Prefix
1128 $dT = mkDataType "Module.T" [] [$con_T1, $con_T2]
1129 -- the [] is for field labels.
1131 instance (Data a, Data b) => Data (T a b) where
1132 gfoldl k z (T1 a b) = z T `k` a `k` b
1133 gfoldl k z T2 = z T2
1134 -- ToDo: add gmapT,Q,M, gfoldr
1136 gunfold k z c = case conIndex c of
1137 I# 1# -> k (k (z T1))
1140 toConstr (T1 _ _) = $cT1
1145 dataCast1 = gcast1 -- If T :: * -> *
1146 dataCast2 = gcast2 -- if T :: * -> * -> *
1150 gen_Data_binds :: SrcSpan
1152 -> (LHsBinds RdrName, -- The method bindings
1153 DerivAuxBinds) -- Auxiliary bindings
1154 gen_Data_binds loc tycon
1155 = (listToBag [gfoldl_bind, gunfold_bind, toCon_bind, dataTypeOf_bind]
1156 `unionBags` gcast_binds,
1157 -- Auxiliary definitions: the data type and constructors
1158 MkTyCon tycon : map MkDataCon data_cons)
1160 data_cons = tyConDataCons tycon
1161 n_cons = length data_cons
1162 one_constr = n_cons == 1
1165 gfoldl_bind = mk_FunBind loc gfoldl_RDR (map gfoldl_eqn data_cons)
1166 gfoldl_eqn con = ([nlVarPat k_RDR, nlVarPat z_RDR, nlConVarPat con_name as_needed],
1167 foldl mk_k_app (nlHsVar z_RDR `nlHsApp` nlHsVar con_name) as_needed)
1170 con_name = getRdrName con
1171 as_needed = take (dataConSourceArity con) as_RDRs
1172 mk_k_app e v = nlHsPar (nlHsOpApp e k_RDR (nlHsVar v))
1174 ------------ gunfold
1175 gunfold_bind = mk_FunBind loc
1177 [([k_Pat, z_Pat, if one_constr then nlWildPat else c_Pat],
1181 | one_constr = mk_unfold_rhs (head data_cons) -- No need for case
1182 | otherwise = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr)
1183 (map gunfold_alt data_cons)
1185 gunfold_alt dc = mkSimpleHsAlt (mk_unfold_pat dc) (mk_unfold_rhs dc)
1186 mk_unfold_rhs dc = foldr nlHsApp
1187 (nlHsVar z_RDR `nlHsApp` nlHsVar (getRdrName dc))
1188 (replicate (dataConSourceArity dc) (nlHsVar k_RDR))
1190 mk_unfold_pat dc -- Last one is a wild-pat, to avoid
1191 -- redundant test, and annoying warning
1192 | tag-fIRST_TAG == n_cons-1 = nlWildPat -- Last constructor
1193 | otherwise = nlConPat intDataCon_RDR [nlLitPat (HsIntPrim (toInteger tag))]
1197 ------------ toConstr
1198 toCon_bind = mk_FunBind loc toConstr_RDR (map to_con_eqn data_cons)
1199 to_con_eqn dc = ([nlWildConPat dc], nlHsVar (mk_constr_name dc))
1201 ------------ dataTypeOf
1202 dataTypeOf_bind = mk_easy_FunBind
1206 (nlHsVar (mk_data_type_name tycon))
1208 ------------ gcast1/2
1209 tycon_kind = tyConKind tycon
1210 gcast_binds | tycon_kind `eqKind` kind1 = mk_gcast dataCast1_RDR gcast1_RDR
1211 | tycon_kind `eqKind` kind2 = mk_gcast dataCast2_RDR gcast2_RDR
1212 | otherwise = emptyBag
1213 mk_gcast dataCast_RDR gcast_RDR
1214 = unitBag (mk_easy_FunBind loc dataCast_RDR [nlVarPat f_RDR]
1215 (nlHsVar gcast_RDR `nlHsApp` nlHsVar f_RDR))
1218 kind1, kind2 :: Kind
1219 kind1 = liftedTypeKind `mkArrowKind` liftedTypeKind
1220 kind2 = liftedTypeKind `mkArrowKind` kind1
1222 gfoldl_RDR, gunfold_RDR, toConstr_RDR, dataTypeOf_RDR, mkConstr_RDR,
1223 mkDataType_RDR, conIndex_RDR, prefix_RDR, infix_RDR,
1224 dataCast1_RDR, dataCast2_RDR, gcast1_RDR, gcast2_RDR :: RdrName
1225 gfoldl_RDR = varQual_RDR gENERICS (fsLit "gfoldl")
1226 gunfold_RDR = varQual_RDR gENERICS (fsLit "gunfold")
1227 toConstr_RDR = varQual_RDR gENERICS (fsLit "toConstr")
1228 dataTypeOf_RDR = varQual_RDR gENERICS (fsLit "dataTypeOf")
1229 dataCast1_RDR = varQual_RDR gENERICS (fsLit "dataCast1")
1230 dataCast2_RDR = varQual_RDR gENERICS (fsLit "dataCast2")
1231 gcast1_RDR = varQual_RDR tYPEABLE (fsLit "gcast1")
1232 gcast2_RDR = varQual_RDR tYPEABLE (fsLit "gcast2")
1233 mkConstr_RDR = varQual_RDR gENERICS (fsLit "mkConstr")
1234 mkDataType_RDR = varQual_RDR gENERICS (fsLit "mkDataType")
1235 conIndex_RDR = varQual_RDR gENERICS (fsLit "constrIndex")
1236 prefix_RDR = dataQual_RDR gENERICS (fsLit "Prefix")
1237 infix_RDR = dataQual_RDR gENERICS (fsLit "Infix")
1242 %************************************************************************
1246 %************************************************************************
1250 data T a = T1 Int a | T2 (T a)
1252 We generate the instance:
1254 instance Functor T where
1255 fmap f (T1 b1 a) = T1 b1 (f a)
1256 fmap f (T2 ta) = T2 (fmap f ta)
1258 Notice that we don't simply apply 'fmap' to the constructor arguments.
1260 - Do nothing to an argument whose type doesn't mention 'a'
1261 - Apply 'f' to an argument of type 'a'
1262 - Apply 'fmap f' to other arguments
1263 That's why we have to recurse deeply into the constructor argument types,
1264 rather than just one level, as we typically do.
1266 What about types with more than one type parameter? In general, we only
1267 derive Functor for the last position:
1269 data S a b = S1 [b] | S2 (a, T a b)
1270 instance Functor (S a) where
1271 fmap f (S1 bs) = S1 (fmap f bs)
1272 fmap f (S2 (p,q)) = S2 (a, fmap f q)
1274 However, we have special cases for
1278 More formally, we write the derivation of fmap code over type variable
1279 'a for type 'b as ($fmap 'a 'b). In this general notation the derived
1282 instance Functor T where
1283 fmap f (T1 x1 x2) = T1 ($(fmap 'a 'b1) x1) ($(fmap 'a 'a) x2)
1284 fmap f (T2 x1) = T2 ($(fmap 'a '(T a)) x1)
1286 $(fmap 'a 'b) x = x -- when b does not contain a
1287 $(fmap 'a 'a) x = f x
1288 $(fmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(fmap 'a 'b1) x1, $(fmap 'a 'b2) x2)
1289 $(fmap 'a '(T b1 b2)) x = fmap $(fmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1290 $(fmap 'a '(b -> c)) x = \b -> $(fmap 'a' 'c) (x ($(cofmap 'a 'b) b))
1292 For functions, the type parameter 'a can occur in a contravariant position,
1293 which means we need to derive a function like:
1295 cofmap :: (a -> b) -> (f b -> f a)
1297 This is pretty much the same as $fmap, only without the $(cofmap 'a 'a) case:
1299 $(cofmap 'a 'b) x = x -- when b does not contain a
1300 $(cofmap 'a 'a) x = error "type variable in contravariant position"
1301 $(cofmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(cofmap 'a 'b1) x1, $(cofmap 'a 'b2) x2)
1302 $(cofmap 'a '[b]) x = map $(cofmap 'a 'b) x
1303 $(cofmap 'a '(T b1 b2)) x = fmap $(cofmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1304 $(cofmap 'a '(b -> c)) x = \b -> $(cofmap 'a' 'c) (x ($(fmap 'a 'c) b))
1307 gen_Functor_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1308 gen_Functor_binds loc tycon
1309 = (unitBag fmap_bind, [])
1311 data_cons = tyConDataCons tycon
1313 fmap_bind = L loc $ mkFunBind (L loc fmap_RDR) (map fmap_eqn data_cons)
1314 fmap_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1316 parts = foldDataConArgs ft_fmap con
1318 ft_fmap :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1319 -- Tricky higher order type; I can't say I fully understand this code :-(
1320 ft_fmap = FT { ft_triv = \x -> return x -- fmap f x = x
1321 , ft_var = \x -> return (nlHsApp f_Expr x) -- fmap f x = f x
1322 , ft_fun = \g h x -> mkSimpleLam (\b -> h =<< (nlHsApp x `fmap` g b))
1323 -- fmap f x = \b -> h (x (g b))
1324 , ft_tup = mkSimpleTupleCase match_for_con -- fmap f x = case x of (a1,a2,..) -> (g1 a1,g2 a2,..)
1325 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- fmap f x = fmap g x
1326 return $ nlHsApps fmap_RDR [gg,x]
1327 , ft_forall = \_ g x -> g x
1328 , ft_bad_app = panic "in other argument"
1329 , ft_co_var = panic "contravariant" }
1331 match_for_con = mkSimpleConMatch $
1332 \con_name xsM -> do xs <- sequence xsM
1333 return (nlHsApps con_name xs) -- Con (g1 v1) (g2 v2) ..
1336 Utility functions related to Functor deriving.
1338 Since several things use the same pattern of traversal, this is abstracted into functorLikeTraverse.
1339 This function works like a fold: it makes a value of type 'a' in a bottom up way.
1342 -- Generic traversal for Functor deriving
1343 data FFoldType a -- Describes how to fold over a Type in a functor like way
1344 = FT { ft_triv :: a -- Does not contain variable
1345 , ft_var :: a -- The variable itself
1346 , ft_co_var :: a -- The variable itself, contravariantly
1347 , ft_fun :: a -> a -> a -- Function type
1348 , ft_tup :: Boxity -> [a] -> a -- Tuple type
1349 , ft_ty_app :: Type -> a -> a -- Type app, variable only in last argument
1350 , ft_bad_app :: a -- Type app, variable other than in last argument
1351 , ft_forall :: TcTyVar -> a -> a -- Forall type
1354 functorLikeTraverse :: TyVar -- ^ Variable to look for
1355 -> FFoldType a -- ^ How to fold
1356 -> Type -- ^ Type to process
1358 functorLikeTraverse var (FT { ft_triv = caseTrivial, ft_var = caseVar
1359 , ft_co_var = caseCoVar, ft_fun = caseFun
1360 , ft_tup = caseTuple, ft_ty_app = caseTyApp
1361 , ft_bad_app = caseWrongArg, ft_forall = caseForAll })
1364 where -- go returns (result of type a, does type contain var)
1365 go co ty | Just ty' <- coreView ty = go co ty'
1366 go co (TyVarTy v) | v == var = (if co then caseCoVar else caseVar,True)
1367 go co (FunTy (PredTy _) b) = go co b
1368 go co (FunTy x y) | xc || yc = (caseFun xr yr,True)
1369 where (xr,xc) = go (not co) x
1371 go co (AppTy x y) | xc = (caseWrongArg, True)
1372 | yc = (caseTyApp x yr, True)
1373 where (_, xc) = go co x
1375 go co ty@(TyConApp con args)
1376 | isTupleTyCon con = (caseTuple (tupleTyConBoxity con) xrs,True)
1377 | null args = (caseTrivial,False) -- T
1378 | or (init xcs) = (caseWrongArg,True) -- T (..var..) ty
1379 | last xcs = -- T (..no var..) ty
1380 (caseTyApp (fst (splitAppTy ty)) (last xrs),True)
1381 where (xrs,xcs) = unzip (map (go co) args)
1382 go co (ForAllTy v x) | v /= var && xc = (caseForAll v xr,True)
1383 where (xr,xc) = go co x
1384 go _ _ = (caseTrivial,False)
1386 -- Return all syntactic subterms of ty that contain var somewhere
1387 -- These are the things that should appear in instance constraints
1388 deepSubtypesContaining :: TyVar -> Type -> [TcType]
1389 deepSubtypesContaining tv
1390 = functorLikeTraverse tv
1393 , ft_fun = (++), ft_tup = \_ xs -> concat xs
1395 , ft_bad_app = panic "in other argument"
1396 , ft_co_var = panic "contravariant"
1397 , ft_forall = \v xs -> filterOut ((v `elemVarSet`) . tyVarsOfType) xs })
1400 foldDataConArgs :: FFoldType a -> DataCon -> [a]
1401 -- Fold over the arguments of the datacon
1402 foldDataConArgs ft con
1403 = map (functorLikeTraverse tv ft) (dataConOrigArgTys con)
1405 tv = last (dataConUnivTyVars con)
1406 -- Argument to derive for, 'a in the above description
1407 -- The validity checks have ensured that con is
1408 -- a vanilla data constructor
1410 -- Make a HsLam using a fresh variable from a State monad
1411 mkSimpleLam :: (LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1412 -- (mkSimpleLam fn) returns (\x. fn(x))
1413 mkSimpleLam lam = do
1416 body <- lam (nlHsVar n)
1417 return (mkHsLam [nlVarPat n] body)
1419 mkSimpleLam2 :: (LHsExpr id -> LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1420 mkSimpleLam2 lam = do
1421 (n1:n2:names) <- get
1423 body <- lam (nlHsVar n1) (nlHsVar n2)
1424 return (mkHsLam [nlVarPat n1,nlVarPat n2] body)
1426 -- "Con a1 a2 a3 -> fold [x1 a1, x2 a2, x3 a3]"
1427 mkSimpleConMatch :: Monad m => (RdrName -> [a] -> m (LHsExpr RdrName)) -> [LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName)
1428 mkSimpleConMatch fold extra_pats con insides = do
1429 let con_name = getRdrName con
1430 let vars_needed = takeList insides as_RDRs
1431 let pat = nlConVarPat con_name vars_needed
1432 rhs <- fold con_name (zipWith ($) insides (map nlHsVar vars_needed))
1433 return $ mkMatch (extra_pats ++ [pat]) rhs emptyLocalBinds
1435 -- "case x of (a1,a2,a3) -> fold [x1 a1, x2 a2, x3 a3]"
1436 mkSimpleTupleCase :: Monad m => ([LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName))
1437 -> Boxity -> [LHsExpr RdrName -> a] -> LHsExpr RdrName -> m (LHsExpr RdrName)
1438 mkSimpleTupleCase match_for_con boxity insides x = do
1439 let con = tupleCon boxity (length insides)
1440 match <- match_for_con [] con insides
1441 return $ nlHsCase x [match]
1445 %************************************************************************
1449 %************************************************************************
1451 Deriving Foldable instances works the same way as Functor instances,
1452 only Foldable instances are not possible for function types at all.
1453 Here the derived instance for the type T above is:
1455 instance Foldable T where
1456 foldr f z (T1 x1 x2 x3) = $(foldr 'a 'b1) x1 ( $(foldr 'a 'a) x2 ( $(foldr 'a 'b2) x3 z ) )
1460 $(foldr 'a 'b) x z = z -- when b does not contain a
1461 $(foldr 'a 'a) x z = f x z
1462 $(foldr 'a '(b1,b2)) x z = case x of (x1,x2) -> $(foldr 'a 'b1) x1 ( $(foldr 'a 'b2) x2 z )
1463 $(foldr 'a '(T b1 b2)) x z = foldr $(foldr 'a 'b2) x z -- when a only occurs in the last parameter, b2
1465 Note that the arguments to the real foldr function are the wrong way around,
1466 since (f :: a -> b -> b), while (foldr f :: b -> t a -> b).
1469 gen_Foldable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1470 gen_Foldable_binds loc tycon
1471 = (unitBag foldr_bind, [])
1473 data_cons = tyConDataCons tycon
1475 foldr_bind = L loc $ mkFunBind (L loc foldr_RDR) (map foldr_eqn data_cons)
1476 foldr_eqn con = evalState (match_for_con z_Expr [f_Pat,z_Pat] con parts) bs_RDRs
1478 parts = foldDataConArgs ft_foldr con
1480 ft_foldr :: FFoldType (LHsExpr RdrName -> LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1481 ft_foldr = FT { ft_triv = \_ z -> return z -- foldr f z x = z
1482 , ft_var = \x z -> return (nlHsApps f_RDR [x,z]) -- foldr f z x = f x z
1483 , ft_tup = \b gs x z -> mkSimpleTupleCase (match_for_con z) b gs x
1484 , ft_ty_app = \_ g x z -> do gg <- mkSimpleLam2 g -- foldr f z x = foldr (\xx zz -> g xx zz) z x
1485 return $ nlHsApps foldable_foldr_RDR [gg,z,x]
1486 , ft_forall = \_ g x z -> g x z
1487 , ft_co_var = panic "covariant"
1488 , ft_fun = panic "function"
1489 , ft_bad_app = panic "in other argument" }
1491 match_for_con z = mkSimpleConMatch (\_con_name -> foldrM ($) z) -- g1 v1 (g2 v2 (.. z))
1495 %************************************************************************
1497 Traversable instances
1499 %************************************************************************
1501 Again, Traversable is much like Functor and Foldable.
1505 $(traverse 'a 'b) x = pure x -- when b does not contain a
1506 $(traverse 'a 'a) x = f x
1507 $(traverse 'a '(b1,b2)) x = case x of (x1,x2) -> (,) <$> $(traverse 'a 'b1) x1 <*> $(traverse 'a 'b2) x2
1508 $(traverse 'a '(T b1 b2)) x = traverse $(traverse 'a 'b2) x -- when a only occurs in the last parameter, b2
1510 Note that the generated code is not as efficient as it could be. For instance:
1512 data T a = T Int a deriving Traversable
1514 gives the function: traverse f (T x y) = T <$> pure x <*> f y
1515 instead of: traverse f (T x y) = T x <$> f y
1518 gen_Traversable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1519 gen_Traversable_binds loc tycon
1520 = (unitBag traverse_bind, [])
1522 data_cons = tyConDataCons tycon
1524 traverse_bind = L loc $ mkFunBind (L loc traverse_RDR) (map traverse_eqn data_cons)
1525 traverse_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1527 parts = foldDataConArgs ft_trav con
1530 ft_trav :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1531 ft_trav = FT { ft_triv = \x -> return (nlHsApps pure_RDR [x]) -- traverse f x = pure x
1532 , ft_var = \x -> return (nlHsApps f_RDR [x]) -- travese f x = f x
1533 , ft_tup = mkSimpleTupleCase match_for_con -- travese f x z = case x of (a1,a2,..) ->
1534 -- (,,) <$> g1 a1 <*> g2 a2 <*> ..
1535 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- travese f x = travese (\xx -> g xx) x
1536 return $ nlHsApps traverse_RDR [gg,x]
1537 , ft_forall = \_ g x -> g x
1538 , ft_co_var = panic "covariant"
1539 , ft_fun = panic "function"
1540 , ft_bad_app = panic "in other argument" }
1542 match_for_con = mkSimpleConMatch $
1543 \con_name xsM -> do xs <- sequence xsM
1544 return (mkApCon (nlHsVar con_name) xs)
1546 -- ((Con <$> x1) <*> x2) <*> ..
1547 mkApCon con [] = nlHsApps pure_RDR [con]
1548 mkApCon con (x:xs) = foldl appAp (nlHsApps fmap_RDR [con,x]) xs
1549 where appAp x y = nlHsApps ap_RDR [x,y]
1554 %************************************************************************
1556 \subsection{Generating extra binds (@con2tag@ and @tag2con@)}
1558 %************************************************************************
1563 con2tag_Foo :: Foo ... -> Int#
1564 tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
1565 maxtag_Foo :: Int -- ditto (NB: not unlifted)
1568 The `tags' here start at zero, hence the @fIRST_TAG@ (currently one)
1572 genAuxBind :: SrcSpan -> DerivAuxBind -> LHsBind RdrName
1573 genAuxBind loc (GenCon2Tag tycon)
1574 | lots_of_constructors
1575 = mk_FunBind loc rdr_name [([], get_tag_rhs)]
1578 = mk_FunBind loc rdr_name (map mk_stuff (tyConDataCons tycon))
1581 rdr_name = con2tag_RDR tycon
1583 tvs = map (mkRdrUnqual . getOccName) (tyConTyVars tycon)
1584 -- We can't use gerRdrName because that makes an Exact RdrName
1585 -- and we can't put them in the LocalRdrEnv
1587 -- Give a signature to the bound variable, so
1588 -- that the case expression generated by getTag is
1589 -- monomorphic. In the push-enter model we get better code.
1590 get_tag_rhs = L loc $ ExprWithTySig
1591 (nlHsLam (mkSimpleHsAlt (nlVarPat a_RDR)
1592 (nlHsApp (nlHsVar getTag_RDR) a_Expr)))
1593 (noLoc (mkExplicitHsForAllTy (map (noLoc.UserTyVar) tvs) (noLoc []) con2tag_ty))
1595 con2tag_ty = nlHsTyConApp (getRdrName tycon) (map nlHsTyVar tvs)
1597 nlHsTyVar (getRdrName intPrimTyCon)
1599 lots_of_constructors = tyConFamilySize tycon > 8
1600 -- was: mAX_FAMILY_SIZE_FOR_VEC_RETURNS
1601 -- but we don't do vectored returns any more.
1603 mk_stuff :: DataCon -> ([LPat RdrName], LHsExpr RdrName)
1604 mk_stuff con = ([nlWildConPat con],
1605 nlHsLit (HsIntPrim (toInteger ((dataConTag con) - fIRST_TAG))))
1607 genAuxBind loc (GenTag2Con tycon)
1608 = mk_FunBind loc rdr_name
1609 [([nlConVarPat intDataCon_RDR [a_RDR]],
1610 noLoc (ExprWithTySig (nlHsApp (nlHsVar tagToEnum_RDR) a_Expr)
1611 (nlHsTyVar (getRdrName tycon))))]
1613 rdr_name = tag2con_RDR tycon
1615 genAuxBind loc (GenMaxTag tycon)
1616 = mkVarBind loc rdr_name
1617 (nlHsApp (nlHsVar intDataCon_RDR) (nlHsLit (HsIntPrim max_tag)))
1619 rdr_name = maxtag_RDR tycon
1620 max_tag = case (tyConDataCons tycon) of
1621 data_cons -> toInteger ((length data_cons) - fIRST_TAG)
1623 genAuxBind loc (MkTyCon tycon) -- $dT
1624 = mkVarBind loc (mk_data_type_name tycon)
1625 ( nlHsVar mkDataType_RDR
1626 `nlHsApp` nlHsLit (mkHsString (showSDocOneLine (ppr tycon)))
1627 `nlHsApp` nlList constrs )
1629 constrs = [nlHsVar (mk_constr_name con) | con <- tyConDataCons tycon]
1631 genAuxBind loc (MkDataCon dc) -- $cT1 etc
1632 = mkVarBind loc (mk_constr_name dc)
1633 (nlHsApps mkConstr_RDR constr_args)
1636 = [ -- nlHsIntLit (toInteger (dataConTag dc)), -- Tag
1637 nlHsVar (mk_data_type_name (dataConTyCon dc)), -- DataType
1638 nlHsLit (mkHsString (occNameString dc_occ)), -- String name
1639 nlList labels, -- Field labels
1640 nlHsVar fixity] -- Fixity
1642 labels = map (nlHsLit . mkHsString . getOccString)
1643 (dataConFieldLabels dc)
1644 dc_occ = getOccName dc
1645 is_infix = isDataSymOcc dc_occ
1646 fixity | is_infix = infix_RDR
1647 | otherwise = prefix_RDR
1649 mk_data_type_name :: TyCon -> RdrName -- "$tT"
1650 mk_data_type_name tycon = mkAuxBinderName (tyConName tycon) mkDataTOcc
1652 mk_constr_name :: DataCon -> RdrName -- "$cC"
1653 mk_constr_name con = mkAuxBinderName (dataConName con) mkDataCOcc
1656 %************************************************************************
1658 \subsection{Utility bits for generating bindings}
1660 %************************************************************************
1663 ToDo: Better SrcLocs.
1667 LHsExpr RdrName -- What to do for equality
1668 -> LHsExpr RdrName -> LHsExpr RdrName
1670 careful_compare_Case :: -- checks for primitive types...
1671 TyCon -- The tycon we are deriving for
1673 -> LHsExpr RdrName -- What to do for equality
1674 -> LHsExpr RdrName -> LHsExpr RdrName
1677 cmp_eq_Expr :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1678 cmp_eq_Expr a b = nlHsApp (nlHsApp (nlHsVar cmp_eq_RDR) a) b
1679 -- Was: compare_gen_Case cmp_eq_RDR
1681 compare_gen_Case (L _ (HsVar eq_tag)) a b | eq_tag == eqTag_RDR
1682 = nlHsApp (nlHsApp (nlHsVar compare_RDR) a) b -- Simple case
1683 compare_gen_Case eq a b -- General case
1684 = nlHsCase (nlHsPar (nlHsApp (nlHsApp (nlHsVar compare_RDR) a) b)) {-of-}
1685 [mkSimpleHsAlt (nlNullaryConPat ltTag_RDR) ltTag_Expr,
1686 mkSimpleHsAlt (nlNullaryConPat eqTag_RDR) eq,
1687 mkSimpleHsAlt (nlNullaryConPat gtTag_RDR) gtTag_Expr]
1689 careful_compare_Case tycon ty eq a b
1690 | not (isUnLiftedType ty)
1691 = compare_gen_Case eq a b
1692 | otherwise -- We have to do something special for primitive things...
1693 = nlHsIf (genOpApp a relevant_lt_op b) -- Test (<) first, not (==), becuase the latter
1694 ltTag_Expr -- is true less often, so putting it first would
1695 -- mean more tests (dynamically)
1696 (nlHsIf (genOpApp a relevant_eq_op b) eq gtTag_Expr)
1698 relevant_eq_op = primOpRdrName (assoc_ty_id "Ord" tycon eq_op_tbl ty)
1699 relevant_lt_op = primOpRdrName (assoc_ty_id "Ord" tycon lt_op_tbl ty)
1702 box_if_necy :: String -- The class involved
1703 -> TyCon -- The tycon involved
1704 -> LHsExpr RdrName -- The argument
1705 -> Type -- The argument type
1706 -> LHsExpr RdrName -- Boxed version of the arg
1707 box_if_necy cls_str tycon arg arg_ty
1708 | isUnLiftedType arg_ty = nlHsApp (nlHsVar box_con) arg
1711 box_con = assoc_ty_id cls_str tycon box_con_tbl arg_ty
1713 assoc_ty_id :: String -- The class involved
1714 -> TyCon -- The tycon involved
1715 -> [(Type,a)] -- The table
1717 -> a -- The result of the lookup
1718 assoc_ty_id cls_str _ tbl ty
1719 | null res = pprPanic "Error in deriving:" (text "Can't derive" <+> text cls_str <+>
1720 text "for primitive type" <+> ppr ty)
1721 | otherwise = head res
1723 res = [id | (ty',id) <- tbl, ty `tcEqType` ty']
1725 eq_op_tbl :: [(Type, PrimOp)]
1727 [(charPrimTy, CharEqOp)
1728 ,(intPrimTy, IntEqOp)
1729 ,(wordPrimTy, WordEqOp)
1730 ,(addrPrimTy, AddrEqOp)
1731 ,(floatPrimTy, FloatEqOp)
1732 ,(doublePrimTy, DoubleEqOp)
1735 lt_op_tbl :: [(Type, PrimOp)]
1737 [(charPrimTy, CharLtOp)
1738 ,(intPrimTy, IntLtOp)
1739 ,(wordPrimTy, WordLtOp)
1740 ,(addrPrimTy, AddrLtOp)
1741 ,(floatPrimTy, FloatLtOp)
1742 ,(doublePrimTy, DoubleLtOp)
1745 box_con_tbl :: [(Type, RdrName)]
1747 [(charPrimTy, getRdrName charDataCon)
1748 ,(intPrimTy, getRdrName intDataCon)
1749 ,(wordPrimTy, wordDataCon_RDR)
1750 ,(floatPrimTy, getRdrName floatDataCon)
1751 ,(doublePrimTy, getRdrName doubleDataCon)
1754 -----------------------------------------------------------------------
1756 and_Expr :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1757 and_Expr a b = genOpApp a and_RDR b
1759 -----------------------------------------------------------------------
1761 eq_Expr :: TyCon -> Type -> LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1762 eq_Expr tycon ty a b = genOpApp a eq_op b
1765 | not (isUnLiftedType ty) = eq_RDR
1766 | otherwise = primOpRdrName (assoc_ty_id "Eq" tycon eq_op_tbl ty)
1767 -- we have to do something special for primitive things...
1771 untag_Expr :: TyCon -> [( RdrName, RdrName)] -> LHsExpr RdrName -> LHsExpr RdrName
1772 untag_Expr _ [] expr = expr
1773 untag_Expr tycon ((untag_this, put_tag_here) : more) expr
1774 = nlHsCase (nlHsPar (nlHsVarApps (con2tag_RDR tycon) [untag_this])) {-of-}
1775 [mkSimpleHsAlt (nlVarPat put_tag_here) (untag_Expr tycon more expr)]
1777 cmp_tags_Expr :: RdrName -- Comparison op
1778 -> RdrName -> RdrName -- Things to compare
1779 -> LHsExpr RdrName -- What to return if true
1780 -> LHsExpr RdrName -- What to return if false
1783 cmp_tags_Expr op a b true_case false_case
1784 = nlHsIf (genOpApp (nlHsVar a) op (nlHsVar b)) true_case false_case
1787 :: LHsExpr RdrName -> LHsExpr RdrName
1789 enum_from_then_to_Expr
1790 :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1793 enum_from_to_Expr f t2 = nlHsApp (nlHsApp (nlHsVar enumFromTo_RDR) f) t2
1794 enum_from_then_to_Expr f t t2 = nlHsApp (nlHsApp (nlHsApp (nlHsVar enumFromThenTo_RDR) f) t) t2
1797 :: LHsExpr RdrName -> LHsExpr RdrName
1800 showParen_Expr e1 e2 = nlHsApp (nlHsApp (nlHsVar showParen_RDR) e1) e2
1802 nested_compose_Expr :: [LHsExpr RdrName] -> LHsExpr RdrName
1804 nested_compose_Expr [] = panic "nested_compose_expr" -- Arg is always non-empty
1805 nested_compose_Expr [e] = parenify e
1806 nested_compose_Expr (e:es)
1807 = nlHsApp (nlHsApp (nlHsVar compose_RDR) (parenify e)) (nested_compose_Expr es)
1809 -- impossible_Expr is used in case RHSs that should never happen.
1810 -- We generate these to keep the desugarer from complaining that they *might* happen!
1811 impossible_Expr :: LHsExpr RdrName
1812 impossible_Expr = nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString "Urk! in TcGenDeriv"))
1814 -- illegal_Expr is used when signalling error conditions in the RHS of a derived
1815 -- method. It is currently only used by Enum.{succ,pred}
1816 illegal_Expr :: String -> String -> String -> LHsExpr RdrName
1817 illegal_Expr meth tp msg =
1818 nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString (meth ++ '{':tp ++ "}: " ++ msg)))
1820 -- illegal_toEnum_tag is an extended version of illegal_Expr, which also allows you
1821 -- to include the value of a_RDR in the error string.
1822 illegal_toEnum_tag :: String -> RdrName -> LHsExpr RdrName
1823 illegal_toEnum_tag tp maxtag =
1824 nlHsApp (nlHsVar error_RDR)
1825 (nlHsApp (nlHsApp (nlHsVar append_RDR)
1826 (nlHsLit (mkHsString ("toEnum{" ++ tp ++ "}: tag ("))))
1827 (nlHsApp (nlHsApp (nlHsApp
1828 (nlHsVar showsPrec_RDR)
1832 (nlHsVar append_RDR)
1833 (nlHsLit (mkHsString ") is outside of enumeration's range (0,")))
1834 (nlHsApp (nlHsApp (nlHsApp
1835 (nlHsVar showsPrec_RDR)
1838 (nlHsLit (mkHsString ")"))))))
1840 parenify :: LHsExpr RdrName -> LHsExpr RdrName
1841 parenify e@(L _ (HsVar _)) = e
1842 parenify e = mkHsPar e
1844 -- genOpApp wraps brackets round the operator application, so that the
1845 -- renamer won't subsequently try to re-associate it.
1846 genOpApp :: LHsExpr RdrName -> RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1847 genOpApp e1 op e2 = nlHsPar (nlHsOpApp e1 op e2)
1851 a_RDR, b_RDR, c_RDR, d_RDR, f_RDR, k_RDR, z_RDR, ah_RDR, bh_RDR, ch_RDR, dh_RDR,
1852 cmp_eq_RDR :: RdrName
1853 a_RDR = mkVarUnqual (fsLit "a")
1854 b_RDR = mkVarUnqual (fsLit "b")
1855 c_RDR = mkVarUnqual (fsLit "c")
1856 d_RDR = mkVarUnqual (fsLit "d")
1857 f_RDR = mkVarUnqual (fsLit "f")
1858 k_RDR = mkVarUnqual (fsLit "k")
1859 z_RDR = mkVarUnqual (fsLit "z")
1860 ah_RDR = mkVarUnqual (fsLit "a#")
1861 bh_RDR = mkVarUnqual (fsLit "b#")
1862 ch_RDR = mkVarUnqual (fsLit "c#")
1863 dh_RDR = mkVarUnqual (fsLit "d#")
1864 cmp_eq_RDR = mkVarUnqual (fsLit "cmp_eq")
1866 as_RDRs, bs_RDRs, cs_RDRs :: [RdrName]
1867 as_RDRs = [ mkVarUnqual (mkFastString ("a"++show i)) | i <- [(1::Int) .. ] ]
1868 bs_RDRs = [ mkVarUnqual (mkFastString ("b"++show i)) | i <- [(1::Int) .. ] ]
1869 cs_RDRs = [ mkVarUnqual (mkFastString ("c"++show i)) | i <- [(1::Int) .. ] ]
1871 a_Expr, b_Expr, c_Expr, f_Expr, z_Expr, ltTag_Expr, eqTag_Expr, gtTag_Expr,
1872 false_Expr, true_Expr :: LHsExpr RdrName
1873 a_Expr = nlHsVar a_RDR
1874 b_Expr = nlHsVar b_RDR
1875 c_Expr = nlHsVar c_RDR
1876 f_Expr = nlHsVar f_RDR
1877 z_Expr = nlHsVar z_RDR
1878 ltTag_Expr = nlHsVar ltTag_RDR
1879 eqTag_Expr = nlHsVar eqTag_RDR
1880 gtTag_Expr = nlHsVar gtTag_RDR
1881 false_Expr = nlHsVar false_RDR
1882 true_Expr = nlHsVar true_RDR
1884 a_Pat, b_Pat, c_Pat, d_Pat, f_Pat, k_Pat, z_Pat :: LPat RdrName
1885 a_Pat = nlVarPat a_RDR
1886 b_Pat = nlVarPat b_RDR
1887 c_Pat = nlVarPat c_RDR
1888 d_Pat = nlVarPat d_RDR
1889 f_Pat = nlVarPat f_RDR
1890 k_Pat = nlVarPat k_RDR
1891 z_Pat = nlVarPat z_RDR
1893 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon -> RdrName
1894 -- Generates Orig s RdrName, for the binding positions
1895 con2tag_RDR tycon = mk_tc_deriv_name tycon mkCon2TagOcc
1896 tag2con_RDR tycon = mk_tc_deriv_name tycon mkTag2ConOcc
1897 maxtag_RDR tycon = mk_tc_deriv_name tycon mkMaxTagOcc
1899 mk_tc_deriv_name :: TyCon -> (OccName -> OccName) -> RdrName
1900 mk_tc_deriv_name tycon occ_fun = mkAuxBinderName (tyConName tycon) occ_fun
1902 mkAuxBinderName :: Name -> (OccName -> OccName) -> RdrName
1903 mkAuxBinderName parent occ_fun = mkRdrUnqual (occ_fun (nameOccName parent))
1904 -- Was: mkDerivedRdrName name occ_fun, which made an original name
1905 -- But: (a) that does not work well for standalone-deriving
1906 -- (b) an unqualified name is just fine, provided it can't clash with user code
1909 s RdrName for PrimOps. Can't be done in PrelNames, because PrimOp imports
1910 PrelNames, so PrelNames can't import PrimOp.
1913 primOpRdrName :: PrimOp -> RdrName
1914 primOpRdrName op = getRdrName (primOpId op)
1916 minusInt_RDR, eqInt_RDR, ltInt_RDR, geInt_RDR, leInt_RDR,
1917 tagToEnum_RDR :: RdrName
1918 minusInt_RDR = primOpRdrName IntSubOp
1919 eqInt_RDR = primOpRdrName IntEqOp
1920 ltInt_RDR = primOpRdrName IntLtOp
1921 geInt_RDR = primOpRdrName IntGeOp
1922 leInt_RDR = primOpRdrName IntLeOp
1923 tagToEnum_RDR = primOpRdrName TagToEnumOp
1925 error_RDR :: RdrName
1926 error_RDR = getRdrName eRROR_ID