lfold: fold a lazy stream

In TobCap/lazystreamr: Provides basic functions that handle lazy stream objects

Description

The order of arguments position is different from that of Haskell's because it is easy for magrittr's pipe to pass a lazy stream as the first argument.

Usage

lfoldl(x, f, init)

lfoldl1(x, f)

lfoldl_dash(x, f, init)

lfoldl1_dash(x, f)

lfoldr(x, f, init)

lfoldr1(x, f)

lscanl(x, f, init)

lscanl1(x, f)

lscanr(x, f, init)

lscanr1(x, f)

lunfold_haskell(x, g)

lunfoldl(x, f_pred, f_map, f_gen)

lunfoldr(x, f_pred, f_map, f_gen)

Arguments

x	a lazy stream
f	function who must takes two areguments
init	initial value if needed
g	a function that takes one argument and returns lcons or lempty
f_pred	a predicate function for unfold
f_map	a mapping function for unfold
f_gen	a generating function for unfold

Examples

lfoldl(1%..%10, `+`, 0) # => 55

lfoldl(1%..%10, function(x,y) paste0("(",x,"+",y,")"), 0)
# => "((((((((((0+1)+2)+3)+4)+5)+6)+7)+8)+9)+10)"
lfoldr(1%..%10, function(x,y) paste0("(",x,"+",y,")"), 0)
# => "(1+(2+(3+(4+(5+(6+(7+(8+(9+(10+0))))))))))"
lscanl(1%..%10,`+`, 0) # => llist(0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55)
## library("magrittr")
## liota() %>% ltake(10) %>% lfoldl1(`+`) # => 45

lunfold_haskell(0, function(x) if (x >= 10) lempty else lcons(x, x + 1))
lunfoldl(1, function(x) x > 10, function(x) x ^ 2, function(x) x + 1)

TobCap/lazystreamr documentation built on May 9, 2019, 4:50 p.m.