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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2015-07-23 12:24:14 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2015-07-23 13:59:23 +0100 |
| commit | 608e76ced1ae2f8a9d2084d3092e37c47480fa91 (patch) | |
| tree | 78360b570fa4795c9839e650803a29a66cb06638 /docs | |
| parent | 7ec07e4027826ad92cf651798cc4b5b9eea34a18 (diff) | |
| download | haskell-608e76ced1ae2f8a9d2084d3092e37c47480fa91.tar.gz | |
Document type functions in the Paterson conditions
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index 2ec1d4e7b5..9685b1d29a 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -5246,7 +5246,12 @@ The Paterson Conditions: for each class constraint <literal>(C t1 ... tn)</liter <orderedlist> <listitem><para>No type variable has more occurrences in the constraint than in the head</para></listitem> <listitem><para>The constraint has fewer constructors and variables (taken together - and counting repetitions) than the head</para></listitem> + and counting repetitions) than the head +</para></listitem> +<listitem><para>The constraint mentions no type functions. +A type function application can in principle expand to a +type of arbitrary size, and so are rejected out of hand +</para></listitem> </orderedlist> </para></listitem> |