CODEWITHSUNDEEP
type-inferencesml
dividebyzero
dividebyzero

Reputation: 1283

define a "trick" standard ML function without specifying explicit type

This is an exercise from the standard ML tutorial seen here: http://homepages.inf.ed.ac.uk/stg/NOTES/node42.html

I am not taking a class so there is no cheating going on here. But I can't figure out how to do this. Can someone help?

The function fn x => fn y => x has type 'a -> ('b -> 'a). Without giving an explicit type constraint, define a function with type 'a -> ('a -> 'a)

Upvotes: 0

Views: 189

Answers (1)

Andreas Rossberg
Andreas Rossberg

Reputation: 36118

Hint 1: You have to find an expression that has 2 or more subexpressions but requires them to have the same type.

Hint 2: Lists or conditionals are good contenders.

Hint 3: Of course, the subexpressions you put in there are the two arguments.

Hint 4: You don't need to use the result of this expression.

Upvotes: 2

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