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Diffstat (limited to 'compiler/prelude/PrelRules.hs')
| -rw-r--r-- | compiler/prelude/PrelRules.hs | 13 |
1 files changed, 0 insertions, 13 deletions
diff --git a/compiler/prelude/PrelRules.hs b/compiler/prelude/PrelRules.hs index e94490007f..28c0628f16 100644 --- a/compiler/prelude/PrelRules.hs +++ b/compiler/prelude/PrelRules.hs @@ -1030,19 +1030,6 @@ dataToTagRule = a `mplus` b guard $ ty1 `eqType` ty2 return tag - -- Why don't we simplify tagToEnum# (dataToTag# x) to x? We would - -- like to, but it seems tricky. See #14282. The trouble is that - -- we never actually see tagToEnum# (dataToTag# x). Because dataToTag# - -- is can_fail, this expression is immediately transformed into - -- - -- case dataToTag# @T x of wild - -- { __DEFAULT -> tagToEnum# @T wild } - -- - -- and wild has no unfolding. Simon Peyton Jones speculates one way around - -- might be to arrange to give unfoldings to case binders of CONLIKE - -- applications and mark dataToTag# CONLIKE, but he doubts it's really - -- worth the trouble. - -- dataToTag (K e1 e2) ==> tag-of K -- This also works (via exprIsConApp_maybe) for -- dataToTag x |