import TysWiredIn
import Match
import PrelNames
-import PrelInfo
import SrcLoc
import Outputable
import FastString
-
-import Control.Monad ( liftM2 )
\end{code}
List comprehensions may be desugared in one of two ways: ``ordinary''
-- 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
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
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
--
dePArrComp (LetStmt ds : qs) body pa cea = do
mapP <- dsLookupGlobalId mapPName
- let xs = map unLoc (collectLocalBinders ds)
+ let xs = collectLocalBinders ds
ty'cea = parrElemType cea
v <- newSysLocalDs ty'cea
clet <- dsLocalBinds ds (mkCoreTup (map Var xs))
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