#4116: Type supplement for constructor specific uses of sum types
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Reporter: gabrielrf | Owner:
Type: proposal | Status: new
Priority: normal | Component: Compiler
Version: | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by gabrielrf):
Final considerations:
Narrowing types with value patterns makes programming cleaner and safer.
Avoids the treatment of out-of-domain values in partially defined
functions
(like constructor-specific functions on sum types) with the corresponding
use of calls to ''error'', exception throwing or ''Maybe'' results.
The value patterns can be gathered at the caller through case analysis
and assigned to as-pattern variables or as refinements of the case
variable,
and checked at compile time when used as actual parameters.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4116#comment:11>
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