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typetraits.arity: improve the documentation; fixes #8965

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Araq 2018-09-15 13:46:00 +02:00
commit 0841eaa273
1 changed files with 7 additions and 2 deletions
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9
lib/pure/typetraits.nim
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@ -35,8 +35,13 @@ proc `$`*(t: typedesc): string =
## An alias for `name`. ## An alias for `name`.
name(t) name(t)
proc arity*(t: typedesc): int {.magic: "TypeTrait".} proc arity*(t: typedesc): int {.magic: "TypeTrait".} =
## Returns the arity of the given type ## Returns the arity of the given type. This is the number of "type" components or
## the number of generic parameters a given type ``t`` has.
runnableExamples:
assert arity(seq[string]) == 1
assert arity(array[3, int]) == 2
assert arity((int, int, float, string)) == 4
proc genericHead*(t: typedesc): typedesc {.magic: "TypeTrait".} proc genericHead*(t: typedesc): typedesc {.magic: "TypeTrait".}
## Accepts an instantiated generic type and returns its ## Accepts an instantiated generic type and returns its