20 行
674 B
TeX
20 行
674 B
TeX
And now we are going to write functions to use it:
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\begin{haskellcode}
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isListEmpty :: List t -> Bool
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isListEmpty Emtpy = True
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isListEmpty x = False
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\end{haskellcode}
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\pause
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We can even have more generic stuff like:
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\begin{haskellcode}
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f :: a -> b
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\end{haskellcode}
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Whatever the function does... it gets something of one type and returns something of another type (it could be the same type, but doesn't need to). That's all we know.
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\vspace{\baselineskip}
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\\
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\pause
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Similarly, remember the function \hinline{head} which gives us the first element of a list? The type signature actually looks like this:
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\begin{haskellcode}
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head :: [a] -> a
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\end{haskellcode}
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Makes sense? |