Commit 9c6014db by mnislaih

### Formatting and minor changes in the ghci debugger section

parent 1b92395b
 ... ... @@ -1826,14 +1826,15 @@ x :: Integer Debugging Higher-Order functions It is possible to use the debugger to examine lambdas. When we are at a breakpoint and a lambda is in scope, the debugger cannot show you the source code that constitutes it; however, it is possible to get some information by applying it to some arguments and observing the result. The process is slightly complicated when the binding is polymorphic. We will use a example to show the process. To keep it simple, we will use the well known map function: We show the process by means of an example. To keep things simple, we will use the well known map function: import Prelude hiding (map) ... ... @@ -1841,6 +1842,7 @@ map :: (a->b) -> a -> b map f [] = [] map f (x:xs) = f x : map f xs We set a breakpoint on map, and call it. *Main> :break map ... ... @@ -1854,10 +1856,11 @@ xs :: [a] GHCi tells us that, among other bindings, f is in scope. However, its type is not fully known yet, and thus it is not possible to apply it yet to any and thus it is not possible to apply it to any arguments. Nevertheless, observe that the type of its first argument is the same as the type of x, and its result type is the same as the type of _result. The debugger has some intelligence built-in to update the type of f whenever the types of x or _result are reconstructed. So what we do in this scenario is ... ... @@ -1868,6 +1871,7 @@ xs :: [a] *Main> :print x x = 1 We can check now that as expected, the type of x has been reconstructed, and with it the type of f has been too: ... ... @@ -1877,6 +1881,7 @@ x :: Integer *Main> :t f f :: Integer -> b From here, we can apply f to any argument of type Integer and observe the results. f. But after that, we are free to use f normally. Tips ... ...
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