[Haskell-cafe] ANN: has-0.4 Entity based records
vogt.adam at gmail.com
Wed May 19 16:31:29 EDT 2010
On Thu, May 13, 2010 at 7:16 PM, HASHIMOTO, Yusaku <nonowarn at gmail.com> wrote:
> Sorry for spamming, what I wanted to write is I think `has' has better
> interface than other record packages in types.
> There are many libraries to write function "takes an record has Foo
> and Bar and returns something." But writing type of the function is
> still difficult. I can't write such types using HList or records
> without reading documents. I think, using has, There's few effort to
> write such types.
In which manner do you need to read less documentation to write:
] f :: Has Foo r => r -> ...
Instead when using HList:
] f :: HasField Foo record fieldType => ...
> I think `has' fits the needs of Haskellers who have the good habit of
> writing a type of a function before its definition.
What does this mean exactly in terms of the type inference possible?
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