diff options
Diffstat (limited to 'docs/users_guide/ghci.xml')
| -rw-r--r-- | docs/users_guide/ghci.xml | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/docs/users_guide/ghci.xml b/docs/users_guide/ghci.xml index b5642b127f..929e9dd376 100644 --- a/docs/users_guide/ghci.xml +++ b/docs/users_guide/ghci.xml @@ -633,9 +633,9 @@ Prelude> it * 2 expression, and if it doesn't have an <literal>IO</literal> type, then it transforms it as follows: an expression <replaceable>e</replaceable> turns into -<screen> - let it = <replaceable>e</replaceable>; - print it +<screen> +let it = <replaceable>e</replaceable>; +print it </screen> which is then run as an IO-action.</para> @@ -644,10 +644,14 @@ Prelude> it * 2 complain:</para> <screen> -Prelude> id -No instance for `Show (a -> a)' -arising from use of `print' -in a `do' expression pattern binding: print it +Prelude> id + +<interactive>:1:0: + No instance for (Show (a -> a)) + arising from use of `print' at <interactive>:1:0-1 + Possible fix: add an instance declaration for (Show (a -> a)) + In the expression: print it + In a 'do' expression: print it </screen> <para>The error message contains some clues as to the @@ -659,14 +663,15 @@ in a `do' expression pattern binding: print it which is of type <literal>a</literal>. eg.:</para> <screen> Prelude> Time.getClockTime +Wed Mar 14 12:23:13 GMT 2001 Prelude> print it Wed Mar 14 12:23:13 GMT 2001 </screen> <para>The corresponding translation for an IO-typed <replaceable>e</replaceable> is -<screen> - it <- <replaceable>e</replaceable> +<screen> +it <- <replaceable>e</replaceable> </screen> </para> |