Type signature

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Current revision

A type signature is a line like

inc :: Num a => a -> a

that tells, what is the type of a variable.

In the example

inc

is the variable and

Num a => a -> a

is its type,

namely a function type.

It is considered good style to add a type signature to every top-level variable.

@@ Line 3: / Line 3: @@
 inc :: Num a => a -> a
 </haskell>
-that tells, what is the type of a variable.
+that tells, what is the [[type]] of a [[variable]].
 In the example <hask>inc</hask> is the variable and <hask>Num a => a -> a</hask> is its type,
-namely a function type.
+namely a [[function]] type.
 It is considered [[Type signatures as good style|good style]] to add a type signature to every [[top-level variable]].