Created
December 10, 2012 17:33
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TypeScript Maybe(I want pattern match..)
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interface Functor { | |
fmap: (any) => any; | |
} | |
interface Monad extends Functor { | |
bind: (any) => Monad; | |
} | |
interface MaybeMatcher { | |
just: (any) => Maybe; | |
nothing: () => Maybe; | |
} | |
interface Maybe extends Monad { | |
fmap: (any) => any; | |
bind: (any) => Maybe; | |
match: (MaybeMatcher) => Maybe; | |
} | |
class Just implements Maybe { | |
private value: any; | |
constructor(a: any) { | |
this.value = a | |
} | |
fmap (f: (any) => any): Just { | |
return new Just(f(this.value)) | |
} | |
bind (f: (any) => Maybe): Maybe { | |
return f(this.value) | |
} | |
match (matcher: MaybeMatcher): Maybe { | |
return matcher.just(this.value) | |
} | |
} | |
class Nothing implements Maybe { | |
fmap (f: (any) => any): Nothing { | |
return this | |
} | |
bind (f: (any) => Maybe): Maybe { | |
return this | |
} | |
match (matcher: MaybeMatcher): Maybe { | |
return matcher.nothing() | |
} | |
} | |
var maybe = new Just("hoge") | |
var matched = maybe.match({ | |
just: (s: any): Maybe => { | |
return new Just(s + "hoge") | |
}, | |
nothing: (): Maybe => { | |
return new Just("nothing..") | |
} | |
}) | |
matched.fmap((s: any): any => {console.log(s)}) |
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