Sharing-aware improvements in a call-by-need functional core language

An Environment for Analyzing Space Optimizations in Call-by-Need Functional Languages

“…5. The fold-function definitions are taken from [15], concat and concatMap are inlined versions of the definitions in [6]. We first consider foldfunctions of Haskell.…”

“…foldr is the usual right-fold, foldl the usual left-fold and foldl' a more strict variant of foldl, which is not completely strict, since the used seq only evaluates w until a value is achieved. Following [15], we use the LRPi to find an example in which foldl is worse than foldr if ) is not fulfilled for s 1 = True, s 2 = False, s 3 = False. A list starting with a single True element followed by k − 1 Falseelements generated using a take-function/list generator approach (using a Peano encoding to represent the numbers) is used as input list.…”

“…time usage (the number of reduction steps), is e.g. [9,10,11] for call-by-name and [8,15,13,14] for call-by-need. There seem to be only a few studies on space improvements, by Gustavsson and Sands [4,5,3].…”