CODEWITHSUNDEEP
frege
Dave Moten
Dave Moten

Reputation: 12097

frege pure functions and performance optimizations

My understanding of haskell's pure functions is that they enable performance optimizations like caching (because a pure function returns the same result for the same input every time). What performance optimizations occur for frege's pure functions?

Upvotes: 1

Views: 128

Answers (1)

Ingo
Ingo

Reputation: 36349

Certainly not caching. I'm not aware of any language that would do this automatically, and for good reasons.

What we do currently is inlining, beta-reduction and elimination of certain value constructions and deconstructions. For example, when you have:

case (\a -> (Just a, Just a)) 42 of (Just b, Just c) -> [c,b]

the compiler just generates code to construct the list

[ 42, 42 ]

This looks not very useful at first sight, since certainly nobody would write such bloated code. However, consider that the lambda expression may be the result of inlining some other function. In fact, in highly abstract code like monadic code, the expansion of the (>>=) operator often leads to code that can be optimized in this way.

While inlining and beta-reduction is good in some cases, one must take care not do overdo it, lest one gets code bloat. Especially in the JVM environment, it is a disadvantage to have huge functions (that is, methods). The JIT can and will do a great job for small methods.

Upvotes: 1

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