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 (showSDoc (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
1146 gen_Data_binds :: SrcSpan
1148 -> (LHsBinds RdrName, -- The method bindings
1149 DerivAuxBinds) -- Auxiliary bindings
1150 gen_Data_binds loc tycon
1151 = (listToBag [gfoldl_bind, gunfold_bind, toCon_bind, dataTypeOf_bind],
1152 -- Auxiliary definitions: the data type and constructors
1153 MkTyCon tycon : map MkDataCon data_cons)
1155 data_cons = tyConDataCons tycon
1156 n_cons = length data_cons
1157 one_constr = n_cons == 1
1160 gfoldl_bind = mk_FunBind loc gfoldl_RDR (map gfoldl_eqn data_cons)
1161 gfoldl_eqn con = ([nlVarPat k_RDR, nlVarPat z_RDR, nlConVarPat con_name as_needed],
1162 foldl mk_k_app (nlHsVar z_RDR `nlHsApp` nlHsVar con_name) as_needed)
1165 con_name = getRdrName con
1166 as_needed = take (dataConSourceArity con) as_RDRs
1167 mk_k_app e v = nlHsPar (nlHsOpApp e k_RDR (nlHsVar v))
1169 ------------ gunfold
1170 gunfold_bind = mk_FunBind loc
1172 [([k_Pat, z_Pat, if one_constr then nlWildPat else c_Pat],
1176 | one_constr = mk_unfold_rhs (head data_cons) -- No need for case
1177 | otherwise = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr)
1178 (map gunfold_alt data_cons)
1180 gunfold_alt dc = mkSimpleHsAlt (mk_unfold_pat dc) (mk_unfold_rhs dc)
1181 mk_unfold_rhs dc = foldr nlHsApp
1182 (nlHsVar z_RDR `nlHsApp` nlHsVar (getRdrName dc))
1183 (replicate (dataConSourceArity dc) (nlHsVar k_RDR))
1185 mk_unfold_pat dc -- Last one is a wild-pat, to avoid
1186 -- redundant test, and annoying warning
1187 | tag-fIRST_TAG == n_cons-1 = nlWildPat -- Last constructor
1188 | otherwise = nlConPat intDataCon_RDR [nlLitPat (HsIntPrim (toInteger tag))]
1192 ------------ toConstr
1193 toCon_bind = mk_FunBind loc toConstr_RDR (map to_con_eqn data_cons)
1194 to_con_eqn dc = ([nlWildConPat dc], nlHsVar (mk_constr_name dc))
1196 ------------ dataTypeOf
1197 dataTypeOf_bind = mk_easy_FunBind
1201 (nlHsVar (mk_data_type_name tycon))
1204 gfoldl_RDR, gunfold_RDR, toConstr_RDR, dataTypeOf_RDR, mkConstr_RDR,
1205 mkDataType_RDR, conIndex_RDR, prefix_RDR, infix_RDR :: RdrName
1206 gfoldl_RDR = varQual_RDR gENERICS (fsLit "gfoldl")
1207 gunfold_RDR = varQual_RDR gENERICS (fsLit "gunfold")
1208 toConstr_RDR = varQual_RDR gENERICS (fsLit "toConstr")
1209 dataTypeOf_RDR = varQual_RDR gENERICS (fsLit "dataTypeOf")
1210 mkConstr_RDR = varQual_RDR gENERICS (fsLit "mkConstr")
1211 mkDataType_RDR = varQual_RDR gENERICS (fsLit "mkDataType")
1212 conIndex_RDR = varQual_RDR gENERICS (fsLit "constrIndex")
1213 prefix_RDR = dataQual_RDR gENERICS (fsLit "Prefix")
1214 infix_RDR = dataQual_RDR gENERICS (fsLit "Infix")
1219 %************************************************************************
1223 %************************************************************************
1227 data T a = T1 Int a | T2 (T a)
1229 We generate the instance:
1231 instance Functor T where
1232 fmap f (T1 b1 a) = T1 b1 (f a)
1233 fmap f (T2 ta) = T2 (fmap f ta)
1235 Notice that we don't simply apply 'fmap' to the constructor arguments.
1237 - Do nothing to an argument whose type doesn't mention 'a'
1238 - Apply 'f' to an argument of type 'a'
1239 - Apply 'fmap f' to other arguments
1240 That's why we have to recurse deeply into the constructor argument types,
1241 rather than just one level, as we typically do.
1243 What about types with more than one type parameter? In general, we only
1244 derive Functor for the last position:
1246 data S a b = S1 [b] | S2 (a, T a b)
1247 instance Functor (S a) where
1248 fmap f (S1 bs) = S1 (fmap f bs)
1249 fmap f (S2 (p,q)) = S2 (a, fmap f q)
1251 However, we have special cases for
1255 More formally, we write the derivation of fmap code over type variable
1256 'a for type 'b as ($fmap 'a 'b). In this general notation the derived
1259 instance Functor T where
1260 fmap f (T1 x1 x2) = T1 ($(fmap 'a 'b1) x1) ($(fmap 'a 'a) x2)
1261 fmap f (T2 x1) = T2 ($(fmap 'a '(T a)) x1)
1263 $(fmap 'a 'b) x = x -- when b does not contain a
1264 $(fmap 'a 'a) x = f x
1265 $(fmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(fmap 'a 'b1) x1, $(fmap 'a 'b2) x2)
1266 $(fmap 'a '(T b1 b2)) x = fmap $(fmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1267 $(fmap 'a '(b -> c)) x = \b -> $(fmap 'a' 'c) (x ($(cofmap 'a 'b) b))
1269 For functions, the type parameter 'a can occur in a contravariant position,
1270 which means we need to derive a function like:
1272 cofmap :: (a -> b) -> (f b -> f a)
1274 This is pretty much the same as $fmap, only without the $(cofmap 'a 'a) case:
1276 $(cofmap 'a 'b) x = x -- when b does not contain a
1277 $(cofmap 'a 'a) x = error "type variable in contravariant position"
1278 $(cofmap 'a '(b1,b2)) x = case x of (x1,x2) -> ($(cofmap 'a 'b1) x1, $(cofmap 'a 'b2) x2)
1279 $(cofmap 'a '[b]) x = map $(cofmap 'a 'b) x
1280 $(cofmap 'a '(T b1 b2)) x = fmap $(cofmap 'a 'b2) x -- when a only occurs in the last parameter, b2
1281 $(cofmap 'a '(b -> c)) x = \b -> $(cofmap 'a' 'c) (x ($(fmap 'a 'c) b))
1284 gen_Functor_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1285 gen_Functor_binds loc tycon
1286 = (unitBag fmap_bind, [])
1288 data_cons = tyConDataCons tycon
1290 fmap_bind = L loc $ mkFunBind (L loc fmap_RDR) (map fmap_eqn data_cons)
1291 fmap_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1293 parts = foldDataConArgs ft_fmap con
1295 ft_fmap :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1296 -- Tricky higher order type; I can't say I fully understand this code :-(
1297 ft_fmap = FT { ft_triv = \x -> return x -- fmap f x = x
1298 , ft_var = \x -> return (nlHsApp f_Expr x) -- fmap f x = f x
1299 , ft_fun = \g h x -> mkSimpleLam (\b -> h =<< (nlHsApp x `fmap` g b))
1300 -- fmap f x = \b -> h (x (g b))
1301 , ft_tup = mkSimpleTupleCase match_for_con -- fmap f x = case x of (a1,a2,..) -> (g1 a1,g2 a2,..)
1302 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- fmap f x = fmap g x
1303 return $ nlHsApps fmap_RDR [gg,x]
1304 , ft_forall = \_ g x -> g x
1305 , ft_bad_app = panic "in other argument"
1306 , ft_co_var = panic "contravariant" }
1308 match_for_con = mkSimpleConMatch $
1309 \con_name xsM -> do xs <- sequence xsM
1310 return (nlHsApps con_name xs) -- Con (g1 v1) (g2 v2) ..
1313 Utility functions related to Functor deriving.
1315 Since several things use the same pattern of traversal, this is abstracted into functorLikeTraverse.
1316 This function works like a fold: it makes a value of type 'a' in a bottom up way.
1319 -- Generic traversal for Functor deriving
1320 data FFoldType a -- Describes how to fold over a Type in a functor like way
1321 = FT { ft_triv :: a -- Does not contain variable
1322 , ft_var :: a -- The variable itself
1323 , ft_co_var :: a -- The variable itself, contravariantly
1324 , ft_fun :: a -> a -> a -- Function type
1325 , ft_tup :: Boxity -> [a] -> a -- Tuple type
1326 , ft_ty_app :: Type -> a -> a -- Type app, variable only in last argument
1327 , ft_bad_app :: a -- Type app, variable other than in last argument
1328 , ft_forall :: TcTyVar -> a -> a -- Forall type
1331 functorLikeTraverse :: TyVar -- ^ Variable to look for
1332 -> FFoldType a -- ^ How to fold
1333 -> Type -- ^ Type to process
1335 functorLikeTraverse var (FT { ft_triv = caseTrivial, ft_var = caseVar
1336 , ft_co_var = caseCoVar, ft_fun = caseFun
1337 , ft_tup = caseTuple, ft_ty_app = caseTyApp
1338 , ft_bad_app = caseWrongArg, ft_forall = caseForAll })
1341 where -- go returns (result of type a, does type contain var)
1342 go co ty | Just ty' <- coreView ty = go co ty'
1343 go co (TyVarTy v) | v == var = (if co then caseCoVar else caseVar,True)
1344 go co (FunTy (PredTy _) b) = go co b
1345 go co (FunTy x y) | xc || yc = (caseFun xr yr,True)
1346 where (xr,xc) = go (not co) x
1348 go co (AppTy x y) | xc = (caseWrongArg, True)
1349 | yc = (caseTyApp x yr, True)
1350 where (_, xc) = go co x
1352 go co ty@(TyConApp con args)
1353 | isTupleTyCon con = (caseTuple (tupleTyConBoxity con) xrs,True)
1354 | null args = (caseTrivial,False) -- T
1355 | or (init xcs) = (caseWrongArg,True) -- T (..var..) ty
1356 | last xcs = -- T (..no var..) ty
1357 (caseTyApp (fst (splitAppTy ty)) (last xrs),True)
1358 where (xrs,xcs) = unzip (map (go co) args)
1359 go co (ForAllTy v x) | v /= var && xc = (caseForAll v xr,True)
1360 where (xr,xc) = go co x
1361 go _ _ = (caseTrivial,False)
1363 -- Return all syntactic subterms of ty that contain var somewhere
1364 -- These are the things that should appear in instance constraints
1365 deepSubtypesContaining :: TyVar -> Type -> [TcType]
1366 deepSubtypesContaining tv
1367 = functorLikeTraverse tv
1370 , ft_fun = (++), ft_tup = \_ xs -> concat xs
1372 , ft_bad_app = panic "in other argument"
1373 , ft_co_var = panic "contravariant"
1374 , ft_forall = \v xs -> filterOut ((v `elemVarSet`) . tyVarsOfType) xs })
1377 foldDataConArgs :: FFoldType a -> DataCon -> [a]
1378 -- Fold over the arguments of the datacon
1379 foldDataConArgs ft con
1380 = map (functorLikeTraverse tv ft) (dataConOrigArgTys con)
1382 tv = last (dataConUnivTyVars con)
1383 -- Argument to derive for, 'a in the above description
1384 -- The validity checks have ensured that con is
1385 -- a vanilla data constructor
1387 -- Make a HsLam using a fresh variable from a State monad
1388 mkSimpleLam :: (LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1389 -- (mkSimpleLam fn) returns (\x. fn(x))
1390 mkSimpleLam lam = do
1393 body <- lam (nlHsVar n)
1394 return (mkHsLam [nlVarPat n] body)
1396 mkSimpleLam2 :: (LHsExpr id -> LHsExpr id -> State [id] (LHsExpr id)) -> State [id] (LHsExpr id)
1397 mkSimpleLam2 lam = do
1398 (n1:n2:names) <- get
1400 body <- lam (nlHsVar n1) (nlHsVar n2)
1401 return (mkHsLam [nlVarPat n1,nlVarPat n2] body)
1403 -- "Con a1 a2 a3 -> fold [x1 a1, x2 a2, x3 a3]"
1404 mkSimpleConMatch :: Monad m => (RdrName -> [a] -> m (LHsExpr RdrName)) -> [LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName)
1405 mkSimpleConMatch fold extra_pats con insides = do
1406 let con_name = getRdrName con
1407 let vars_needed = takeList insides as_RDRs
1408 let pat = nlConVarPat con_name vars_needed
1409 rhs <- fold con_name (zipWith ($) insides (map nlHsVar vars_needed))
1410 return $ mkMatch (extra_pats ++ [pat]) rhs emptyLocalBinds
1412 -- "case x of (a1,a2,a3) -> fold [x1 a1, x2 a2, x3 a3]"
1413 mkSimpleTupleCase :: Monad m => ([LPat RdrName] -> DataCon -> [LHsExpr RdrName -> a] -> m (LMatch RdrName))
1414 -> Boxity -> [LHsExpr RdrName -> a] -> LHsExpr RdrName -> m (LHsExpr RdrName)
1415 mkSimpleTupleCase match_for_con boxity insides x = do
1416 let con = tupleCon boxity (length insides)
1417 match <- match_for_con [] con insides
1418 return $ nlHsCase x [match]
1422 %************************************************************************
1426 %************************************************************************
1428 Deriving Foldable instances works the same way as Functor instances,
1429 only Foldable instances are not possible for function types at all.
1430 Here the derived instance for the type T above is:
1432 instance Foldable T where
1433 foldr f z (T1 x1 x2 x3) = $(foldr 'a 'b1) x1 ( $(foldr 'a 'a) x2 ( $(foldr 'a 'b2) x3 z ) )
1437 $(foldr 'a 'b) x z = z -- when b does not contain a
1438 $(foldr 'a 'a) x z = f x z
1439 $(foldr 'a '(b1,b2)) x z = case x of (x1,x2) -> $(foldr 'a 'b1) x1 ( $(foldr 'a 'b2) x2 z )
1440 $(foldr 'a '(T b1 b2)) x z = foldr $(foldr 'a 'b2) x z -- when a only occurs in the last parameter, b2
1442 Note that the arguments to the real foldr function are the wrong way around,
1443 since (f :: a -> b -> b), while (foldr f :: b -> t a -> b).
1446 gen_Foldable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1447 gen_Foldable_binds loc tycon
1448 = (unitBag foldr_bind, [])
1450 data_cons = tyConDataCons tycon
1452 foldr_bind = L loc $ mkFunBind (L loc foldr_RDR) (map foldr_eqn data_cons)
1453 foldr_eqn con = evalState (match_for_con z_Expr [f_Pat,z_Pat] con parts) bs_RDRs
1455 parts = foldDataConArgs ft_foldr con
1457 ft_foldr :: FFoldType (LHsExpr RdrName -> LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1458 ft_foldr = FT { ft_triv = \_ z -> return z -- foldr f z x = z
1459 , ft_var = \x z -> return (nlHsApps f_RDR [x,z]) -- foldr f z x = f x z
1460 , ft_tup = \b gs x z -> mkSimpleTupleCase (match_for_con z) b gs x
1461 , ft_ty_app = \_ g x z -> do gg <- mkSimpleLam2 g -- foldr f z x = foldr (\xx zz -> g xx zz) z x
1462 return $ nlHsApps foldable_foldr_RDR [gg,z,x]
1463 , ft_forall = \_ g x z -> g x z
1464 , ft_co_var = panic "covariant"
1465 , ft_fun = panic "function"
1466 , ft_bad_app = panic "in other argument" }
1468 match_for_con z = mkSimpleConMatch (\_con_name -> foldrM ($) z) -- g1 v1 (g2 v2 (.. z))
1472 %************************************************************************
1474 Traversable instances
1476 %************************************************************************
1478 Again, Traversable is much like Functor and Foldable.
1482 $(traverse 'a 'b) x = pure x -- when b does not contain a
1483 $(traverse 'a 'a) x = f x
1484 $(traverse 'a '(b1,b2)) x = case x of (x1,x2) -> (,) <$> $(traverse 'a 'b1) x1 <*> $(traverse 'a 'b2) x2
1485 $(traverse 'a '(T b1 b2)) x = traverse $(traverse 'a 'b2) x -- when a only occurs in the last parameter, b2
1487 Note that the generated code is not as efficient as it could be. For instance:
1489 data T a = T Int a deriving Traversable
1491 gives the function: traverse f (T x y) = T <$> pure x <*> f y
1492 instead of: traverse f (T x y) = T x <$> f y
1495 gen_Traversable_binds :: SrcSpan -> TyCon -> (LHsBinds RdrName, DerivAuxBinds)
1496 gen_Traversable_binds loc tycon
1497 = (unitBag traverse_bind, [])
1499 data_cons = tyConDataCons tycon
1501 traverse_bind = L loc $ mkFunBind (L loc traverse_RDR) (map traverse_eqn data_cons)
1502 traverse_eqn con = evalState (match_for_con [f_Pat] con parts) bs_RDRs
1504 parts = foldDataConArgs ft_trav con
1507 ft_trav :: FFoldType (LHsExpr RdrName -> State [RdrName] (LHsExpr RdrName))
1508 ft_trav = FT { ft_triv = \x -> return (nlHsApps pure_RDR [x]) -- traverse f x = pure x
1509 , ft_var = \x -> return (nlHsApps f_RDR [x]) -- travese f x = f x
1510 , ft_tup = mkSimpleTupleCase match_for_con -- travese f x z = case x of (a1,a2,..) ->
1511 -- (,,) <$> g1 a1 <*> g2 a2 <*> ..
1512 , ft_ty_app = \_ g x -> do gg <- mkSimpleLam g -- travese f x = travese (\xx -> g xx) x
1513 return $ nlHsApps traverse_RDR [gg,x]
1514 , ft_forall = \_ g x -> g x
1515 , ft_co_var = panic "covariant"
1516 , ft_fun = panic "function"
1517 , ft_bad_app = panic "in other argument" }
1519 match_for_con = mkSimpleConMatch $
1520 \con_name xsM -> do xs <- sequence xsM
1521 return (mkApCon (nlHsVar con_name) xs)
1523 -- ((Con <$> x1) <*> x2) <*> ..
1524 mkApCon con [] = nlHsApps pure_RDR [con]
1525 mkApCon con (x:xs) = foldl appAp (nlHsApps fmap_RDR [con,x]) xs
1526 where appAp x y = nlHsApps ap_RDR [x,y]
1531 %************************************************************************
1533 \subsection{Generating extra binds (@con2tag@ and @tag2con@)}
1535 %************************************************************************
1540 con2tag_Foo :: Foo ... -> Int#
1541 tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
1542 maxtag_Foo :: Int -- ditto (NB: not unlifted)
1545 The `tags' here start at zero, hence the @fIRST_TAG@ (currently one)
1549 genAuxBind :: SrcSpan -> DerivAuxBind -> LHsBind RdrName
1550 genAuxBind loc (GenCon2Tag tycon)
1551 | lots_of_constructors
1552 = mk_FunBind loc rdr_name [([], get_tag_rhs)]
1555 = mk_FunBind loc rdr_name (map mk_stuff (tyConDataCons tycon))
1558 rdr_name = con2tag_RDR tycon
1560 tvs = map (mkRdrUnqual . getOccName) (tyConTyVars tycon)
1561 -- We can't use gerRdrName because that makes an Exact RdrName
1562 -- and we can't put them in the LocalRdrEnv
1564 -- Give a signature to the bound variable, so
1565 -- that the case expression generated by getTag is
1566 -- monomorphic. In the push-enter model we get better code.
1567 get_tag_rhs = L loc $ ExprWithTySig
1568 (nlHsLam (mkSimpleHsAlt (nlVarPat a_RDR)
1569 (nlHsApp (nlHsVar getTag_RDR) a_Expr)))
1570 (noLoc (mkExplicitHsForAllTy (map (noLoc.UserTyVar) tvs) (noLoc []) con2tag_ty))
1572 con2tag_ty = nlHsTyConApp (getRdrName tycon) (map nlHsTyVar tvs)
1574 nlHsTyVar (getRdrName intPrimTyCon)
1576 lots_of_constructors = tyConFamilySize tycon > 8
1577 -- was: mAX_FAMILY_SIZE_FOR_VEC_RETURNS
1578 -- but we don't do vectored returns any more.
1580 mk_stuff :: DataCon -> ([LPat RdrName], LHsExpr RdrName)
1581 mk_stuff con = ([nlWildConPat con],
1582 nlHsLit (HsIntPrim (toInteger ((dataConTag con) - fIRST_TAG))))
1584 genAuxBind loc (GenTag2Con tycon)
1585 = mk_FunBind loc rdr_name
1586 [([nlConVarPat intDataCon_RDR [a_RDR]],
1587 noLoc (ExprWithTySig (nlHsApp (nlHsVar tagToEnum_RDR) a_Expr)
1588 (nlHsTyVar (getRdrName tycon))))]
1590 rdr_name = tag2con_RDR tycon
1592 genAuxBind loc (GenMaxTag tycon)
1593 = mkVarBind loc rdr_name
1594 (nlHsApp (nlHsVar intDataCon_RDR) (nlHsLit (HsIntPrim max_tag)))
1596 rdr_name = maxtag_RDR tycon
1597 max_tag = case (tyConDataCons tycon) of
1598 data_cons -> toInteger ((length data_cons) - fIRST_TAG)
1600 genAuxBind loc (MkTyCon tycon) -- $dT
1601 = mkVarBind loc (mk_data_type_name tycon)
1602 ( nlHsVar mkDataType_RDR
1603 `nlHsApp` nlHsLit (mkHsString (showSDoc (ppr tycon)))
1604 `nlHsApp` nlList constrs )
1606 constrs = [nlHsVar (mk_constr_name con) | con <- tyConDataCons tycon]
1608 genAuxBind loc (MkDataCon dc) -- $cT1 etc
1609 = mkVarBind loc (mk_constr_name dc)
1610 (nlHsApps mkConstr_RDR constr_args)
1613 = [ -- nlHsIntLit (toInteger (dataConTag dc)), -- Tag
1614 nlHsVar (mk_data_type_name (dataConTyCon dc)), -- DataType
1615 nlHsLit (mkHsString (occNameString dc_occ)), -- String name
1616 nlList labels, -- Field labels
1617 nlHsVar fixity] -- Fixity
1619 labels = map (nlHsLit . mkHsString . getOccString)
1620 (dataConFieldLabels dc)
1621 dc_occ = getOccName dc
1622 is_infix = isDataSymOcc dc_occ
1623 fixity | is_infix = infix_RDR
1624 | otherwise = prefix_RDR
1626 mk_data_type_name :: TyCon -> RdrName -- "$tT"
1627 mk_data_type_name tycon = mkAuxBinderName (tyConName tycon) mkDataTOcc
1629 mk_constr_name :: DataCon -> RdrName -- "$cC"
1630 mk_constr_name con = mkAuxBinderName (dataConName con) mkDataCOcc
1633 %************************************************************************
1635 \subsection{Utility bits for generating bindings}
1637 %************************************************************************
1640 ToDo: Better SrcLocs.
1644 LHsExpr RdrName -- What to do for equality
1645 -> LHsExpr RdrName -> LHsExpr RdrName
1647 careful_compare_Case :: -- checks for primitive types...
1648 TyCon -- The tycon we are deriving for
1650 -> LHsExpr RdrName -- What to do for equality
1651 -> LHsExpr RdrName -> LHsExpr RdrName
1654 cmp_eq_Expr :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1655 cmp_eq_Expr a b = nlHsApp (nlHsApp (nlHsVar cmp_eq_RDR) a) b
1656 -- Was: compare_gen_Case cmp_eq_RDR
1658 compare_gen_Case (L _ (HsVar eq_tag)) a b | eq_tag == eqTag_RDR
1659 = nlHsApp (nlHsApp (nlHsVar compare_RDR) a) b -- Simple case
1660 compare_gen_Case eq a b -- General case
1661 = nlHsCase (nlHsPar (nlHsApp (nlHsApp (nlHsVar compare_RDR) a) b)) {-of-}
1662 [mkSimpleHsAlt (nlNullaryConPat ltTag_RDR) ltTag_Expr,
1663 mkSimpleHsAlt (nlNullaryConPat eqTag_RDR) eq,
1664 mkSimpleHsAlt (nlNullaryConPat gtTag_RDR) gtTag_Expr]
1666 careful_compare_Case tycon ty eq a b
1667 | not (isUnLiftedType ty)
1668 = compare_gen_Case eq a b
1669 | otherwise -- We have to do something special for primitive things...
1670 = nlHsIf (genOpApp a relevant_lt_op b) -- Test (<) first, not (==), becuase the latter
1671 ltTag_Expr -- is true less often, so putting it first would
1672 -- mean more tests (dynamically)
1673 (nlHsIf (genOpApp a relevant_eq_op b) eq gtTag_Expr)
1675 relevant_eq_op = primOpRdrName (assoc_ty_id "Ord" tycon eq_op_tbl ty)
1676 relevant_lt_op = primOpRdrName (assoc_ty_id "Ord" tycon lt_op_tbl ty)
1679 box_if_necy :: String -- The class involved
1680 -> TyCon -- The tycon involved
1681 -> LHsExpr RdrName -- The argument
1682 -> Type -- The argument type
1683 -> LHsExpr RdrName -- Boxed version of the arg
1684 box_if_necy cls_str tycon arg arg_ty
1685 | isUnLiftedType arg_ty = nlHsApp (nlHsVar box_con) arg
1688 box_con = assoc_ty_id cls_str tycon box_con_tbl arg_ty
1690 assoc_ty_id :: String -- The class involved
1691 -> TyCon -- The tycon involved
1692 -> [(Type,a)] -- The table
1694 -> a -- The result of the lookup
1695 assoc_ty_id cls_str _ tbl ty
1696 | null res = pprPanic "Error in deriving:" (text "Can't derive" <+> text cls_str <+>
1697 text "for primitive type" <+> ppr ty)
1698 | otherwise = head res
1700 res = [id | (ty',id) <- tbl, ty `tcEqType` ty']
1702 eq_op_tbl :: [(Type, PrimOp)]
1704 [(charPrimTy, CharEqOp)
1705 ,(intPrimTy, IntEqOp)
1706 ,(wordPrimTy, WordEqOp)
1707 ,(addrPrimTy, AddrEqOp)
1708 ,(floatPrimTy, FloatEqOp)
1709 ,(doublePrimTy, DoubleEqOp)
1712 lt_op_tbl :: [(Type, PrimOp)]
1714 [(charPrimTy, CharLtOp)
1715 ,(intPrimTy, IntLtOp)
1716 ,(wordPrimTy, WordLtOp)
1717 ,(addrPrimTy, AddrLtOp)
1718 ,(floatPrimTy, FloatLtOp)
1719 ,(doublePrimTy, DoubleLtOp)
1722 box_con_tbl :: [(Type, RdrName)]
1724 [(charPrimTy, getRdrName charDataCon)
1725 ,(intPrimTy, getRdrName intDataCon)
1726 ,(wordPrimTy, wordDataCon_RDR)
1727 ,(floatPrimTy, getRdrName floatDataCon)
1728 ,(doublePrimTy, getRdrName doubleDataCon)
1731 -----------------------------------------------------------------------
1733 and_Expr :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1734 and_Expr a b = genOpApp a and_RDR b
1736 -----------------------------------------------------------------------
1738 eq_Expr :: TyCon -> Type -> LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1739 eq_Expr tycon ty a b = genOpApp a eq_op b
1742 | not (isUnLiftedType ty) = eq_RDR
1743 | otherwise = primOpRdrName (assoc_ty_id "Eq" tycon eq_op_tbl ty)
1744 -- we have to do something special for primitive things...
1748 untag_Expr :: TyCon -> [( RdrName, RdrName)] -> LHsExpr RdrName -> LHsExpr RdrName
1749 untag_Expr _ [] expr = expr
1750 untag_Expr tycon ((untag_this, put_tag_here) : more) expr
1751 = nlHsCase (nlHsPar (nlHsVarApps (con2tag_RDR tycon) [untag_this])) {-of-}
1752 [mkSimpleHsAlt (nlVarPat put_tag_here) (untag_Expr tycon more expr)]
1754 cmp_tags_Expr :: RdrName -- Comparison op
1755 -> RdrName -> RdrName -- Things to compare
1756 -> LHsExpr RdrName -- What to return if true
1757 -> LHsExpr RdrName -- What to return if false
1760 cmp_tags_Expr op a b true_case false_case
1761 = nlHsIf (genOpApp (nlHsVar a) op (nlHsVar b)) true_case false_case
1764 :: LHsExpr RdrName -> LHsExpr RdrName
1766 enum_from_then_to_Expr
1767 :: LHsExpr RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1770 enum_from_to_Expr f t2 = nlHsApp (nlHsApp (nlHsVar enumFromTo_RDR) f) t2
1771 enum_from_then_to_Expr f t t2 = nlHsApp (nlHsApp (nlHsApp (nlHsVar enumFromThenTo_RDR) f) t) t2
1774 :: LHsExpr RdrName -> LHsExpr RdrName
1777 showParen_Expr e1 e2 = nlHsApp (nlHsApp (nlHsVar showParen_RDR) e1) e2
1779 nested_compose_Expr :: [LHsExpr RdrName] -> LHsExpr RdrName
1781 nested_compose_Expr [] = panic "nested_compose_expr" -- Arg is always non-empty
1782 nested_compose_Expr [e] = parenify e
1783 nested_compose_Expr (e:es)
1784 = nlHsApp (nlHsApp (nlHsVar compose_RDR) (parenify e)) (nested_compose_Expr es)
1786 -- impossible_Expr is used in case RHSs that should never happen.
1787 -- We generate these to keep the desugarer from complaining that they *might* happen!
1788 impossible_Expr :: LHsExpr RdrName
1789 impossible_Expr = nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString "Urk! in TcGenDeriv"))
1791 -- illegal_Expr is used when signalling error conditions in the RHS of a derived
1792 -- method. It is currently only used by Enum.{succ,pred}
1793 illegal_Expr :: String -> String -> String -> LHsExpr RdrName
1794 illegal_Expr meth tp msg =
1795 nlHsApp (nlHsVar error_RDR) (nlHsLit (mkHsString (meth ++ '{':tp ++ "}: " ++ msg)))
1797 -- illegal_toEnum_tag is an extended version of illegal_Expr, which also allows you
1798 -- to include the value of a_RDR in the error string.
1799 illegal_toEnum_tag :: String -> RdrName -> LHsExpr RdrName
1800 illegal_toEnum_tag tp maxtag =
1801 nlHsApp (nlHsVar error_RDR)
1802 (nlHsApp (nlHsApp (nlHsVar append_RDR)
1803 (nlHsLit (mkHsString ("toEnum{" ++ tp ++ "}: tag ("))))
1804 (nlHsApp (nlHsApp (nlHsApp
1805 (nlHsVar showsPrec_RDR)
1809 (nlHsVar append_RDR)
1810 (nlHsLit (mkHsString ") is outside of enumeration's range (0,")))
1811 (nlHsApp (nlHsApp (nlHsApp
1812 (nlHsVar showsPrec_RDR)
1815 (nlHsLit (mkHsString ")"))))))
1817 parenify :: LHsExpr RdrName -> LHsExpr RdrName
1818 parenify e@(L _ (HsVar _)) = e
1819 parenify e = mkHsPar e
1821 -- genOpApp wraps brackets round the operator application, so that the
1822 -- renamer won't subsequently try to re-associate it.
1823 genOpApp :: LHsExpr RdrName -> RdrName -> LHsExpr RdrName -> LHsExpr RdrName
1824 genOpApp e1 op e2 = nlHsPar (nlHsOpApp e1 op e2)
1828 a_RDR, b_RDR, c_RDR, d_RDR, f_RDR, k_RDR, z_RDR, ah_RDR, bh_RDR, ch_RDR, dh_RDR,
1829 cmp_eq_RDR :: RdrName
1830 a_RDR = mkVarUnqual (fsLit "a")
1831 b_RDR = mkVarUnqual (fsLit "b")
1832 c_RDR = mkVarUnqual (fsLit "c")
1833 d_RDR = mkVarUnqual (fsLit "d")
1834 f_RDR = mkVarUnqual (fsLit "f")
1835 k_RDR = mkVarUnqual (fsLit "k")
1836 z_RDR = mkVarUnqual (fsLit "z")
1837 ah_RDR = mkVarUnqual (fsLit "a#")
1838 bh_RDR = mkVarUnqual (fsLit "b#")
1839 ch_RDR = mkVarUnqual (fsLit "c#")
1840 dh_RDR = mkVarUnqual (fsLit "d#")
1841 cmp_eq_RDR = mkVarUnqual (fsLit "cmp_eq")
1843 as_RDRs, bs_RDRs, cs_RDRs :: [RdrName]
1844 as_RDRs = [ mkVarUnqual (mkFastString ("a"++show i)) | i <- [(1::Int) .. ] ]
1845 bs_RDRs = [ mkVarUnqual (mkFastString ("b"++show i)) | i <- [(1::Int) .. ] ]
1846 cs_RDRs = [ mkVarUnqual (mkFastString ("c"++show i)) | i <- [(1::Int) .. ] ]
1848 a_Expr, b_Expr, c_Expr, f_Expr, z_Expr, ltTag_Expr, eqTag_Expr, gtTag_Expr,
1849 false_Expr, true_Expr :: LHsExpr RdrName
1850 a_Expr = nlHsVar a_RDR
1851 b_Expr = nlHsVar b_RDR
1852 c_Expr = nlHsVar c_RDR
1853 f_Expr = nlHsVar f_RDR
1854 z_Expr = nlHsVar z_RDR
1855 ltTag_Expr = nlHsVar ltTag_RDR
1856 eqTag_Expr = nlHsVar eqTag_RDR
1857 gtTag_Expr = nlHsVar gtTag_RDR
1858 false_Expr = nlHsVar false_RDR
1859 true_Expr = nlHsVar true_RDR
1861 a_Pat, b_Pat, c_Pat, d_Pat, f_Pat, k_Pat, z_Pat :: LPat RdrName
1862 a_Pat = nlVarPat a_RDR
1863 b_Pat = nlVarPat b_RDR
1864 c_Pat = nlVarPat c_RDR
1865 d_Pat = nlVarPat d_RDR
1866 f_Pat = nlVarPat f_RDR
1867 k_Pat = nlVarPat k_RDR
1868 z_Pat = nlVarPat z_RDR
1870 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon -> RdrName
1871 -- Generates Orig s RdrName, for the binding positions
1872 con2tag_RDR tycon = mk_tc_deriv_name tycon mkCon2TagOcc
1873 tag2con_RDR tycon = mk_tc_deriv_name tycon mkTag2ConOcc
1874 maxtag_RDR tycon = mk_tc_deriv_name tycon mkMaxTagOcc
1876 mk_tc_deriv_name :: TyCon -> (OccName -> OccName) -> RdrName
1877 mk_tc_deriv_name tycon occ_fun = mkAuxBinderName (tyConName tycon) occ_fun
1879 mkAuxBinderName :: Name -> (OccName -> OccName) -> RdrName
1880 mkAuxBinderName parent occ_fun = mkRdrUnqual (occ_fun (nameOccName parent))
1881 -- Was: mkDerivedRdrName name occ_fun, which made an original name
1882 -- But: (a) that does not work well for standalone-deriving
1883 -- (b) an unqualified name is just fine, provided it can't clash with user code
1886 s RdrName for PrimOps. Can't be done in PrelNames, because PrimOp imports
1887 PrelNames, so PrelNames can't import PrimOp.
1890 primOpRdrName :: PrimOp -> RdrName
1891 primOpRdrName op = getRdrName (primOpId op)
1893 minusInt_RDR, eqInt_RDR, ltInt_RDR, geInt_RDR, leInt_RDR,
1894 tagToEnum_RDR :: RdrName
1895 minusInt_RDR = primOpRdrName IntSubOp
1896 eqInt_RDR = primOpRdrName IntEqOp
1897 ltInt_RDR = primOpRdrName IntLtOp
1898 geInt_RDR = primOpRdrName IntGeOp
1899 leInt_RDR = primOpRdrName IntLeOp
1900 tagToEnum_RDR = primOpRdrName TagToEnumOp
1902 error_RDR :: RdrName
1903 error_RDR = getRdrName eRROR_ID