Allow parametrized yet monomorphic data types in {#pointer ... #}

[ian-ross]

Bug imported from C2HS Trac

Trac ticket created: 2011-01-26T12:46:00-0800

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Hello.

Currently pointer declaration could only use non-parametrized types. But sometimes it's too restrictive. I think examples below are self-explanatory:

This is OK but pointer is untyped

{#pointer *OKA__Hit as OKA_Hit #}

This doesn't work although it's perfectly sound. On syntactic level it may require addition of parenthesis.

{#pointer *OKA__Hit as OKA_Hit -> Hit Chan () #}

./Event.chs:23: (column 42) [ERROR]  >>> Syntax error!
  The phrase `Chan' is not allowed here.

There is workaround with type synonyms but it's not very elegant.

type Typedef = Hit Chan ()
{#pointer *OKA__Hit as OKA_Hit -> Typedef #}

[ian-ross]

This is now implemented in HEAD, although the syntax is a little different from what was proposed. Specifically, you need to write

{#pointer *OKA__Hit as OKA_Hit -> `Hit Chan ()' #}

to use parametrized types on the right hand side of the arrow in pointer hooks. (This is because the parser for what can appear inside C2HS hooks doesn't include a full Haskell parser, so you need to mark verbatim Haskell code with a backquote-forward quote pair.)