prelude.flint

# higher-level dips
op dip2 = 'dip cons dip
op dip3 = 'dip cons dip2

# take a number of elems from a list
op take = [] 'cons rolldown times

# list length functions
op length = [pop 1 +] swap 0 swap fold
op small = length 2 <

# append 2 lists
op append = quote ~

# concatenate 2 lists with an element in the middle
op enconcat = 'cons dip swap ~

# apply a quote to 2 elements of the stack
op app2 = dup 'swap dip unary 'unary dip

# recursive combinators
op genrec = 4 take dup unquote ['rolldown dip swap] dip ['genrec ~ quote ~] dip ~ ifte
op linrec = 'unquote swap ~ genrec
op binrec = 'app2 swap ~ genrec
op tailrec = [] linrec

# higher-order list functions
op split = dup 'not ~ ['filter cons] app2 cleave
op fold = [dup null] [pop 'pop dip] [uncons 'rollup dip 'dup dip2] [rollup 2 n-ary] linrec
op map = [uncons swap] swap ~ 'swap ~ [dup null] [pop []] rolldown 'cons linrec
op filter = swap [] swap ['dup swap ~ 'unary cons [[swap cons] 'pop ifte] cons] dip2 fold