tcfail010.hs:3:
Ambiguous type variable(s) `t' in the constraint `Num [t]'
- arising from use of `+' at tcfail010.hs:3
+ arising from the literal `2' at tcfail010.hs:3
+ In the second argument of `+', namely `2'
In the right-hand side of a lambda abstraction: z + 2
Compilation had errors