On Sat, 1 Mar 2014 21:35:09 +0900, KwangYul Seo
In Java, the Checker Framework ( http://types.cs.washington.edu/checker-framework/) provides a way to type check string literals. For example, Java signatures type system differentiates strings literals in different forms:
1. Unqualified strings : "Hello, world!" -> @Unqualified String
2. Fully qualified names: "package.Outer.Inner" -> @FullyQualifiedString String
3. Binary names: "package.Outer$Inner" -> @BinaryName String
4. Field descriptors: "Lpackage/Outer$Inner;" -> @FieldDescriptor String
It can do the similar checks with regular expressions or SQL statements.
Is it possible to type check string literals in Haskell? I think it would be nice if we can check if a given string literal is a valid URL or an email address at compile time.
Regards, Kwang Yul Seo Non-text part: text/html _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
I think QuasiQuoters were designed for pretty much this purpose. They're basically functions from Strings to expressions (or types/declarations/patterns, depending on the context). A quasiquoter like [url|http://example.com] could parse the string passed to it ("http://example.com") at compile time and return an expression of type URL (or throw an error or something else), or maybe even some other data structure that will end up being useful.