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https://github.com/nim-lang/Nim.git
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ac5435ecd0
* Allow empty new-styled concept Slightly improve error messages * Make empty new-styled concepts an error
106 lines
1.6 KiB
Nim
106 lines
1.6 KiB
Nim
discard """
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output: '''4
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0
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4
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4
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1
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2
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3
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yes int
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string int'''
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joinable: false
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"""
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import hashes
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type
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Comparable = concept # no T, an atom
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proc cmp(a, b: Self): int
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ToStringable = concept
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proc `$`(a: Self): string
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Hashable = concept ## the most basic of identity assumptions
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proc hash(x: Self): int
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proc `==`(x, y: Self): bool
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Swapable = concept
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proc swap(x, y: var Self)
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proc h(x: Hashable) =
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echo x
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h(4)
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when true:
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proc compare(a: Comparable) =
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echo cmp(a, a)
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compare(4)
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proc dollar(x: ToStringable) =
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echo x
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when true:
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dollar 4
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dollar "4"
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#type D = distinct int
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#dollar D(4)
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when true:
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type
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Iterable[Ix] = concept
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iterator items(c: Self): Ix
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proc g[Tu](it: Iterable[Tu]) =
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for x in it:
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echo x
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g(@[1, 2, 3])
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proc hs(x: Swapable) =
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var y = x
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swap y, y
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hs(4)
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type
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Indexable[T] = concept # has a T, a collection
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proc `[]`(a: Self; index: int): T # we need to describe how to infer 'T'
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# and then we can use the 'T' and it must match:
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proc `[]=`(a: var Self; index: int; value: T)
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proc len(a: Self): int
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proc indexOf[T](a: Indexable[T]; value: T) =
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echo "yes ", T
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block:
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var x = @[1, 2, 3]
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indexOf(x, 4)
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import tables, typetraits
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type
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Dict[K, V] = concept
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proc `[]`(s: Self; k: K): V
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proc `[]=`(s: var Self; k: K; v: V)
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proc d[K2, V2](x: Dict[K2, V2]) =
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echo K2, " ", V2
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var x = initTable[string, int]()
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d(x)
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type Monoid = concept
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proc `+`(x, y: Self): Self
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proc z(t: typedesc[Self]): Self
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proc z(x: typedesc[int]): int = 0
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doAssert int is Monoid
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