diff options
| author | sheaf <sam.derbyshire@gmail.com> | 2022-02-25 12:11:01 +0100 |
|---|---|---|
| committer | Zubin Duggal <zubin.duggal@gmail.com> | 2022-05-09 13:14:37 +0530 |
| commit | 509ed1a9b8c5a507e3d0886a6d3a933e492b9e4c (patch) | |
| tree | 806c924b14313bc19486594e74ecfd7a46186dad /docs | |
| parent | 19d2143a6d41951f2cec8a5d7033584d99161359 (diff) | |
| download | haskell-509ed1a9b8c5a507e3d0886a6d3a933e492b9e4c.tar.gz | |
GHCi: don't normalise partially instantiated types
This patch skips performing type normalisation when we haven't
fully instantiated the type. That is, in tcRnExpr
(used only for :type in GHCi), skip normalisation if
the result type responds True to isSigmaTy.
Fixes #20974
(cherry picked from commit 4ad8ce0b5c741862e2f94fd362077068b9b669d3)
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/ghci.rst | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/docs/users_guide/ghci.rst b/docs/users_guide/ghci.rst index ebafc7fda5..6585d297a3 100644 --- a/docs/users_guide/ghci.rst +++ b/docs/users_guide/ghci.rst @@ -2981,13 +2981,19 @@ commonly used commands. Infers and prints the type of ⟨expression⟩. For polymorphic types it instantiates the 'inferred' forall quantifiers (but not the - 'specified' ones; see :ref:`inferred-vs-specified`), solves constraints, and re-generalises. + 'specified' ones; see :ref:`inferred-vs-specified`), solves constraints, + re-generalises, and then reduces type families as much as possible. .. code-block:: none *X> :type length length :: Foldable t => t a -> Int + Type family reduction is skipped if the function is not fully instantiated, + as this has been observed to give more intuitive results. + You may want to use :ghci-cmd:`:info` if you are not applying any arguments, + as that will return the original type of the function without instantiating. + .. ghci-cmd:: :type +v; ⟨expression⟩ Infers and prints the type of ⟨expression⟩, binding inferred type variables |