Desugaring list comprehensions and array comprehensions
\begin{code}
-{-# OPTIONS -w #-}
+{-# OPTIONS -fno-warn-incomplete-patterns #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and fix
-- any warnings in the module. See
import {-# SOURCE #-} DsExpr ( dsLExpr, dsLocalBinds )
-import BasicTypes
import HsSyn
import TcHsSyn
import CoreSyn
+import MkCore
import DsMonad -- the monadery used in the desugarer
import DsUtils
import DynFlags
import CoreUtils
-import Var
+import Id
import Type
-import TysPrim
import TysWiredIn
import Match
import PrelNames
-import PrelInfo
import SrcLoc
-import Panic
import Outputable
-
-import Control.Monad ( liftM2 )
+import FastString
\end{code}
List comprehensions may be desugared in one of two ways: ``ordinary''
dflags <- getDOptsDs
let quals = map unLoc lquals
- if not (dopt Opt_RewriteRules dflags) || dopt Opt_IgnoreInterfacePragmas dflags
+ if not (dopt Opt_EnableRewriteRules dflags) || dopt Opt_IgnoreInterfacePragmas dflags
-- Either rules are switched off, or we are ignoring what there are;
-- Either way foldr/build won't happen, so use the more efficient
-- Wadler-style desugaring
|| isParallelComp quals
-- Foldr-style desugaring can't handle parallel list comprehensions
then deListComp quals body (mkNilExpr elt_ty)
- else do -- Foldr/build should be enabled, so desugar
- -- into foldrs and builds
- [n_tyvar] <- newTyVarsDs [alphaTyVar]
-
- let n_ty = mkTyVarTy n_tyvar
- c_ty = mkFunTys [elt_ty, n_ty] n_ty
- [c, n] <- newSysLocalsDs [c_ty, n_ty]
-
- result <- dfListComp c n quals body
- build_id <- dsLookupGlobalId buildName
- returnDs (Var build_id `App` Type elt_ty `App` mkLams [n_tyvar, c, n] result)
+ else mkBuildExpr elt_ty (\(c, _) (n, _) -> dfListComp c n quals body)
+ -- Foldr/build should be enabled, so desugar
+ -- into foldrs and builds
where
-- We must test for ParStmt anywhere, not just at the head, because an extension
-- Given such a statement it gives you back an expression representing how to compute the transformed
-- list and the tuple that you need to bind from that list in order to proceed with your desugaring
dsTransformStmt :: Stmt Id -> DsM (CoreExpr, LPat Id)
-dsTransformStmt (TransformStmt (stmts, binders) usingExpr maybeByExpr) = do
+dsTransformStmt (TransformStmt stmts binders usingExpr maybeByExpr) = do
(expr, binders_tuple_type) <- dsInnerListComp (stmts, binders)
usingExpr' <- dsLExpr usingExpr
-- Given such a statement it gives you back an expression representing how to compute the transformed
-- list and the tuple that you need to bind from that list in order to proceed with your desugaring
dsGroupStmt :: Stmt Id -> DsM (CoreExpr, LPat Id)
-dsGroupStmt (GroupStmt (stmts, binderMap) groupByClause) = do
+dsGroupStmt (GroupStmt stmts binderMap by using) = do
let (fromBinders, toBinders) = unzip binderMap
fromBindersTypes = map idType fromBinders
toBindersTupleType = mkBigCoreTupTy toBindersTypes
-- Desugar an inner comprehension which outputs a list of tuples of the "from" binders
- (expr, fromBindersTupleType) <- dsInnerListComp (stmts, fromBinders)
+ (expr, from_tup_ty) <- dsInnerListComp (stmts, fromBinders)
-- Work out what arguments should be supplied to that expression: i.e. is an extraction
-- function required? If so, create that desugared function and add to arguments
- (usingExpr', usingArgs) <-
- case groupByClause of
- GroupByNothing usingExpr -> liftM2 (,) (dsLExpr usingExpr) (return [expr])
- GroupBySomething usingExpr byExpr -> do
- usingExpr' <- dsLExpr (either id noLoc usingExpr)
-
- byExpr' <- dsLExpr byExpr
-
- us <- newUniqueSupply
- [fromBindersTuple] <- newSysLocalsDs [fromBindersTupleType]
- let byExprWrapper = mkTupleCase us fromBinders byExpr' fromBindersTuple (Var fromBindersTuple)
-
- return (usingExpr', [Lam fromBindersTuple byExprWrapper, expr])
+ usingExpr' <- dsLExpr (either id noLoc using)
+ usingArgs <- case by of
+ Nothing -> return [expr]
+ Just by_e -> do { by_e' <- dsLExpr by_e
+ ; us <- newUniqueSupply
+ ; [from_tup_id] <- newSysLocalsDs [from_tup_ty]
+ ; let by_wrap = mkTupleCase us fromBinders by_e'
+ from_tup_id (Var from_tup_id)
+ ; return [Lam from_tup_id by_wrap, expr] }
-- Create an unzip function for the appropriate arity and element types and find "map"
(unzip_fn, unzip_rhs) <- mkUnzipBind fromBindersTypes
-- Generate the expressions to build the grouped list
let -- First we apply the grouping function to the inner list
- inner_list_expr = mkApps usingExpr' ((Type fromBindersTupleType) : usingArgs)
+ inner_list_expr = mkApps usingExpr' ((Type from_tup_ty) : usingArgs)
-- Then we map our "unzip" across it to turn the lists of tuples into tuples of lists
-- We make sure we instantiate the type variable "a" to be a list of "from" tuples and
-- the "b" to be a tuple of "to" lists!
unzipped_inner_list_expr = mkApps (Var map_id)
- [Type (mkListTy fromBindersTupleType), Type toBindersTupleType, Var unzip_fn, inner_list_expr]
+ [Type (mkListTy from_tup_ty), Type toBindersTupleType, Var unzip_fn, inner_list_expr]
-- Then finally we bind the unzip function around that expression
bound_unzipped_inner_list_expr = Let (Rec [(unzip_fn, unzip_rhs)]) unzipped_inner_list_expr
deListComp (ParStmt stmtss_w_bndrs : quals) body list
= do
- exps_and_qual_tys <- mappM dsInnerListComp stmtss_w_bndrs
+ exps_and_qual_tys <- mapM dsInnerListComp stmtss_w_bndrs
let (exps, qual_tys) = unzip exps_and_qual_tys
(zip_fn, zip_rhs) <- mkZipBind qual_tys
bndrs_s = map snd stmtss_w_bndrs
-- pat is the pattern ((x1,..,xn), (y1,..,ym)) in the example above
- pat = mkBigLHsPatTup pats
+ pat = mkBigLHsPatTup pats
pats = map mkBigLHsVarPatTup bndrs_s
-- Last: the one to return
-deListComp [] body list -- Figure 7.4, SLPJ, p 135, rule C above
- = dsLExpr body `thenDs` \ core_body ->
- returnDs (mkConsExpr (exprType core_body) core_body list)
+deListComp [] body list = do -- Figure 7.4, SLPJ, p 135, rule C above
+ core_body <- dsLExpr body
+ return (mkConsExpr (exprType core_body) core_body list)
-- Non-last: must be a guard
-deListComp (ExprStmt guard _ _ : quals) body list -- rule B above
- = dsLExpr guard `thenDs` \ core_guard ->
- deListComp quals body list `thenDs` \ core_rest ->
- returnDs (mkIfThenElse core_guard core_rest list)
+deListComp (ExprStmt guard _ _ : quals) body list = do -- rule B above
+ core_guard <- dsLExpr guard
+ core_rest <- deListComp quals body list
+ return (mkIfThenElse core_guard core_rest list)
-- [e | let B, qs] = let B in [e | qs]
-deListComp (LetStmt binds : quals) body list
- = deListComp quals body list `thenDs` \ core_rest ->
+deListComp (LetStmt binds : quals) body list = do
+ core_rest <- deListComp quals body list
dsLocalBinds binds core_rest
-deListComp (stmt@(TransformStmt _ _ _) : quals) body list = do
+deListComp (stmt@(TransformStmt {}) : quals) body list = do
(inner_list_expr, pat) <- dsTransformStmt stmt
deBindComp pat inner_list_expr quals body list
-deListComp (stmt@(GroupStmt _ _) : quals) body list = do
+deListComp (stmt@(GroupStmt {}) : quals) body list = do
(inner_list_expr, pat) <- dsGroupStmt stmt
deBindComp pat inner_list_expr quals body list
-deListComp (BindStmt pat list1 _ _ : quals) body core_list2 -- rule A' above
- = dsLExpr list1 `thenDs` \ core_list1 ->
+deListComp (BindStmt pat list1 _ _ : quals) body core_list2 = do -- rule A' above
+ core_list1 <- dsLExpr list1
deBindComp pat core_list1 quals body core_list2
\end{code}
\begin{code}
+deBindComp :: OutPat Id
+ -> CoreExpr
+ -> [Stmt Id]
+ -> LHsExpr Id
+ -> CoreExpr
+ -> DsM (Expr Id)
deBindComp pat core_list1 quals body core_list2 = do
let
u3_ty@u1_ty = exprType core_list1 -- two names, same thing
-> DsM CoreExpr
-- Last: the one to return
-dfListComp c_id n_id [] body
- = dsLExpr body `thenDs` \ core_body ->
- returnDs (mkApps (Var c_id) [core_body, Var n_id])
+dfListComp c_id n_id [] body = do
+ core_body <- dsLExpr body
+ return (mkApps (Var c_id) [core_body, Var n_id])
-- Non-last: must be a guard
-dfListComp c_id n_id (ExprStmt guard _ _ : quals) body
- = dsLExpr guard `thenDs` \ core_guard ->
- dfListComp c_id n_id quals body `thenDs` \ core_rest ->
- returnDs (mkIfThenElse core_guard core_rest (Var n_id))
-
-dfListComp c_id n_id (LetStmt binds : quals) body
- -- new in 1.3, local bindings
- = dfListComp c_id n_id quals body `thenDs` \ core_rest ->
+dfListComp c_id n_id (ExprStmt guard _ _ : quals) body = do
+ core_guard <- dsLExpr guard
+ core_rest <- dfListComp c_id n_id quals body
+ return (mkIfThenElse core_guard core_rest (Var n_id))
+
+dfListComp c_id n_id (LetStmt binds : quals) body = do
+ -- new in 1.3, local bindings
+ core_rest <- dfListComp c_id n_id quals body
dsLocalBinds binds core_rest
-dfListComp c_id n_id (stmt@(TransformStmt _ _ _) : quals) body = do
+dfListComp c_id n_id (stmt@(TransformStmt {}) : quals) body = do
(inner_list_expr, pat) <- dsTransformStmt stmt
-- Anyway, we bind the newly transformed list via the generic binding function
dfBindComp c_id n_id (pat, inner_list_expr) quals body
-dfListComp c_id n_id (stmt@(GroupStmt _ _) : quals) body = do
+dfListComp c_id n_id (stmt@(GroupStmt {}) : quals) body = do
(inner_list_expr, pat) <- dsGroupStmt stmt
-- Anyway, we bind the newly grouped list via the generic binding function
dfBindComp c_id n_id (pat, inner_list_expr) quals body
pat core_rest (Var b)
-- now build the outermost foldr, and return
- foldr_id <- dsLookupGlobalId foldrName
- return (Var foldr_id `App` Type x_ty
- `App` Type b_ty
- `App` mkLams [x, b] core_expr
- `App` Var n_id
- `App` core_list1)
-
+ mkFoldrExpr x_ty b_ty (mkLams [x, b] core_expr) (Var n_id) core_list1
\end{code}
%************************************************************************
-- (a2:as'2) -> (a1, a2) : zip as'1 as'2)]
mkZipBind elt_tys = do
- ass <- mappM newSysLocalDs elt_list_tys
- as' <- mappM newSysLocalDs elt_tys
- as's <- mappM newSysLocalDs elt_list_tys
+ ass <- mapM newSysLocalDs elt_list_tys
+ as' <- mapM newSysLocalDs elt_tys
+ as's <- mapM newSysLocalDs elt_list_tys
zip_fn <- newSysLocalDs zip_fn_ty
ax <- newSysLocalDs elt_tuple_ty
axs <- newSysLocalDs elt_list_tuple_ty
ys <- newSysLocalDs elt_tuple_list_ty
- xs <- mappM newSysLocalDs elt_tys
- xss <- mappM newSysLocalDs elt_list_tys
+ xs <- mapM newSysLocalDs elt_tys
+ xss <- mapM newSysLocalDs elt_list_tys
unzip_fn <- newSysLocalDs unzip_fn_ty
- foldr_id <- dsLookupGlobalId foldrName
[us1, us2] <- sequence [newUniqueSupply, newUniqueSupply]
let nil_tuple = mkBigCoreTup (map mkNilExpr elt_tys)
folder_body_outer_case = mkTupleCase us2 xs folder_body_inner_case ax (Var ax)
folder_body = mkLams [ax, axs] folder_body_outer_case
- unzip_body = mkApps (Var foldr_id) [Type elt_tuple_ty, Type elt_list_tuple_ty, folder_body, nil_tuple, Var ys]
- unzip_body_saturated = mkLams [ys] unzip_body
-
- return (unzip_fn, unzip_body_saturated)
+ unzip_body <- mkFoldrExpr elt_tuple_ty elt_list_tuple_ty folder_body nil_tuple (Var ys)
+ return (unzip_fn, mkLams [ys] unzip_body)
where
elt_tuple_ty = mkBigCoreTupTy elt_tys
elt_tuple_list_ty = mkListTy elt_tuple_ty
-> DsM CoreExpr
dsPArrComp [ParStmt qss] body _ = -- parallel comprehension
dePArrParComp qss body
-dsPArrComp qs body _ = -- no ParStmt in `qs'
- dsLookupGlobalId singletonPName `thenDs` \sglP ->
- let unitArray = mkApps (Var sglP) [Type unitTy,
- mkCoreTup []]
- in
- dePArrComp qs body (mkLHsPatTup []) unitArray
+
+-- Special case for simple generators:
+--
+-- <<[:e' | p <- e, qs:]>> = <<[: e' | qs :]>> p e
+--
+-- if matching again p cannot fail, or else
+--
+-- <<[:e' | p <- e, qs:]>> =
+-- <<[:e' | qs:]>> p (filterP (\x -> case x of {p -> True; _ -> False}) e)
+--
+dsPArrComp (BindStmt p e _ _ : qs) body _ = do
+ filterP <- dsLookupGlobalId filterPName
+ ce <- dsLExpr e
+ let ety'ce = parrElemType ce
+ false = Var falseDataConId
+ true = Var trueDataConId
+ v <- newSysLocalDs ety'ce
+ pred <- matchSimply (Var v) (StmtCtxt PArrComp) p true false
+ let gen | isIrrefutableHsPat p = ce
+ | otherwise = mkApps (Var filterP) [Type ety'ce, mkLams [v] pred, ce]
+ dePArrComp qs body p gen
+
+dsPArrComp qs body _ = do -- no ParStmt in `qs'
+ sglP <- dsLookupGlobalId singletonPName
+ let unitArray = mkApps (Var sglP) [Type unitTy, mkCoreTup []]
+ dePArrComp qs body (noLoc $ WildPat unitTy) unitArray
--
-- <<[:e' | :]>> pa ea = mapP (\pa -> e') ea
--
-dePArrComp [] e' pa cea =
- dsLookupGlobalId mapPName `thenDs` \mapP ->
- let ty = parrElemType cea
- in
- deLambda ty pa e' `thenDs` \(clam,
- ty'e') ->
- returnDs $ mkApps (Var mapP) [Type ty, Type ty'e', clam, cea]
+dePArrComp [] e' pa cea = do
+ mapP <- dsLookupGlobalId mapPName
+ let ty = parrElemType cea
+ (clam, ty'e') <- deLambda ty pa e'
+ return $ mkApps (Var mapP) [Type ty, Type ty'e', clam, cea]
--
-- <<[:e' | b, qs:]>> pa ea = <<[:e' | qs:]>> pa (filterP (\pa -> b) ea)
--
-dePArrComp (ExprStmt b _ _ : qs) body pa cea =
- dsLookupGlobalId filterPName `thenDs` \filterP ->
- let ty = parrElemType cea
- in
- deLambda ty pa b `thenDs` \(clam,_) ->
- dePArrComp qs body pa (mkApps (Var filterP) [Type ty, clam, cea])
+dePArrComp (ExprStmt b _ _ : qs) body pa cea = do
+ filterP <- dsLookupGlobalId filterPName
+ let ty = parrElemType cea
+ (clam,_) <- deLambda ty pa b
+ dePArrComp qs body pa (mkApps (Var filterP) [Type ty, clam, cea])
--
-- <<[:e' | p <- e, qs:]>> pa ea =
-- in
-- <<[:e' | qs:]>> (pa, p) (crossMapP ea ef)
--
-dePArrComp (BindStmt p e _ _ : qs) body pa cea =
- dsLookupGlobalId filterPName `thenDs` \filterP ->
- dsLookupGlobalId crossMapPName `thenDs` \crossMapP ->
- dsLExpr e `thenDs` \ce ->
- let ety'cea = parrElemType cea
- ety'ce = parrElemType ce
- false = Var falseDataConId
- true = Var trueDataConId
- in
- newSysLocalDs ety'ce `thenDs` \v ->
- matchSimply (Var v) (StmtCtxt PArrComp) p true false `thenDs` \pred ->
- let cef | isIrrefutableHsPat p = ce
- | otherwise = mkApps (Var filterP) [Type ety'ce, mkLams [v] pred, ce]
- in
- mkLambda ety'cea pa cef `thenDs` \(clam,
- _ ) ->
- let ety'cef = ety'ce -- filter doesn't change the element type
- pa' = mkLHsPatTup [pa, p]
- in
- dePArrComp qs body pa' (mkApps (Var crossMapP)
- [Type ety'cea, Type ety'cef, cea, clam])
+dePArrComp (BindStmt p e _ _ : qs) body pa cea = do
+ filterP <- dsLookupGlobalId filterPName
+ crossMapP <- dsLookupGlobalId crossMapPName
+ ce <- dsLExpr e
+ let ety'cea = parrElemType cea
+ ety'ce = parrElemType ce
+ false = Var falseDataConId
+ true = Var trueDataConId
+ v <- newSysLocalDs ety'ce
+ pred <- matchSimply (Var v) (StmtCtxt PArrComp) p true false
+ let cef | isIrrefutableHsPat p = ce
+ | otherwise = mkApps (Var filterP) [Type ety'ce, mkLams [v] pred, ce]
+ (clam, _) <- mkLambda ety'cea pa cef
+ let ety'cef = ety'ce -- filter doesn't change the element type
+ pa' = mkLHsPatTup [pa, p]
+
+ dePArrComp qs body pa' (mkApps (Var crossMapP)
+ [Type ety'cea, Type ety'cef, cea, clam])
--
-- <<[:e' | let ds, qs:]>> pa ea =
-- <<[:e' | qs:]>> (pa, (x_1, ..., x_n))
-- where
-- {x_1, ..., x_n} = DV (ds) -- Defined Variables
--
-dePArrComp (LetStmt ds : qs) body pa cea =
- dsLookupGlobalId mapPName `thenDs` \mapP ->
- let xs = map unLoc (collectLocalBinders ds)
- ty'cea = parrElemType cea
- in
- newSysLocalDs ty'cea `thenDs` \v ->
- dsLocalBinds ds (mkCoreTup (map Var xs)) `thenDs` \clet ->
- newSysLocalDs (exprType clet) `thenDs` \let'v ->
- let projBody = mkDsLet (NonRec let'v clet) $
- mkCoreTup [Var v, Var let'v]
- errTy = exprType projBody
- errMsg = "DsListComp.dePArrComp: internal error!"
- in
- mkErrorAppDs pAT_ERROR_ID errTy errMsg `thenDs` \cerr ->
- matchSimply (Var v) (StmtCtxt PArrComp) pa projBody cerr`thenDs` \ccase ->
- let pa' = mkLHsPatTup [pa, mkLHsPatTup (map nlVarPat xs)]
- proj = mkLams [v] ccase
- in
- dePArrComp qs body pa' (mkApps (Var mapP)
- [Type ty'cea, Type errTy, proj, cea])
+dePArrComp (LetStmt ds : qs) body pa cea = do
+ mapP <- dsLookupGlobalId mapPName
+ let xs = collectLocalBinders ds
+ ty'cea = parrElemType cea
+ v <- newSysLocalDs ty'cea
+ clet <- dsLocalBinds ds (mkCoreTup (map Var xs))
+ let'v <- newSysLocalDs (exprType clet)
+ let projBody = mkCoreLet (NonRec let'v clet) $
+ mkCoreTup [Var v, Var let'v]
+ errTy = exprType projBody
+ errMsg = ptext (sLit "DsListComp.dePArrComp: internal error!")
+ cerr <- mkErrorAppDs pAT_ERROR_ID errTy errMsg
+ ccase <- matchSimply (Var v) (StmtCtxt PArrComp) pa projBody cerr
+ let pa' = mkLHsPatTup [pa, mkLHsPatTup (map nlVarPat xs)]
+ proj = mkLams [v] ccase
+ dePArrComp qs body pa' (mkApps (Var mapP)
+ [Type ty'cea, Type errTy, proj, cea])
--
-- The parser guarantees that parallel comprehensions can only appear as
-- singeltons qualifier lists, which we already special case in the caller.
-- where
-- {x_1, ..., x_n} = DV (qs)
--
-dePArrParComp qss body =
- deParStmt qss `thenDs` \(pQss,
- ceQss) ->
- dePArrComp [] body pQss ceQss
+dePArrParComp :: [([LStmt Id], [Id])] -> LHsExpr Id -> DsM CoreExpr
+dePArrParComp qss body = do
+ (pQss, ceQss) <- deParStmt qss
+ dePArrComp [] body pQss ceQss
where
deParStmt [] =
-- empty parallel statement lists have no source representation
panic "DsListComp.dePArrComp: Empty parallel list comprehension"
- deParStmt ((qs, xs):qss) = -- first statement
- let res_expr = mkLHsVarTup xs
- in
- dsPArrComp (map unLoc qs) res_expr undefined `thenDs` \cqs ->
+ deParStmt ((qs, xs):qss) = do -- first statement
+ let res_expr = mkLHsVarTuple xs
+ cqs <- dsPArrComp (map unLoc qs) res_expr undefined
parStmts qss (mkLHsVarPatTup xs) cqs
---
parStmts [] pa cea = return (pa, cea)
- parStmts ((qs, xs):qss) pa cea = -- subsequent statements (zip'ed)
- dsLookupGlobalId zipPName `thenDs` \zipP ->
+ parStmts ((qs, xs):qss) pa cea = do -- subsequent statements (zip'ed)
+ zipP <- dsLookupGlobalId zipPName
let pa' = mkLHsPatTup [pa, mkLHsVarPatTup xs]
- ty'cea = parrElemType cea
- res_expr = mkLHsVarTup xs
- in
- dsPArrComp (map unLoc qs) res_expr undefined `thenDs` \cqs ->
+ ty'cea = parrElemType cea
+ res_expr = mkLHsVarTuple xs
+ cqs <- dsPArrComp (map unLoc qs) res_expr undefined
let ty'cqs = parrElemType cqs
- cea' = mkApps (Var zipP) [Type ty'cea, Type ty'cqs, cea, cqs]
- in
+ cea' = mkApps (Var zipP) [Type ty'cea, Type ty'cqs, cea, cqs]
parStmts qss pa' cea'
-- generate Core corresponding to `\p -> e'
-> LHsExpr Id -- body
-> DsM (CoreExpr, Type)
deLambda ty p e =
- dsLExpr e `thenDs` \ce ->
- mkLambda ty p ce
+ mkLambda ty p =<< dsLExpr e
-- generate Core for a lambda pattern match, where the body is already in Core
--
-> LPat Id -- argument pattern
-> CoreExpr -- desugared body
-> DsM (CoreExpr, Type)
-mkLambda ty p ce =
- newSysLocalDs ty `thenDs` \v ->
- let errMsg = "DsListComp.deLambda: internal error!"
- ce'ty = exprType ce
- in
- mkErrorAppDs pAT_ERROR_ID ce'ty errMsg `thenDs` \cerr ->
- matchSimply (Var v) (StmtCtxt PArrComp) p ce cerr `thenDs` \res ->
- returnDs (mkLams [v] res, ce'ty)
+mkLambda ty p ce = do
+ v <- newSysLocalDs ty
+ let errMsg = ptext (sLit "DsListComp.deLambda: internal error!")
+ ce'ty = exprType ce
+ cerr <- mkErrorAppDs pAT_ERROR_ID ce'ty errMsg
+ res <- matchSimply (Var v) (StmtCtxt PArrComp) p ce cerr
+ return (mkLams [v] res, ce'ty)
-- obtain the element type of the parallel array produced by the given Core
-- expression
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