module MicroKanren::Lisp
Public Instance Methods
assp(func, alist)
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Search association list by predicate function. Based on lua implementation by silentbicycle: github.com/silentbicycle/lua-ukanren/blob/master/ukanren.lua#L53:L61
Additional reference for this function is scheme: Ref for assp: www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-4.html
# File lib/micro_kanren/lisp.rb, line 39 def assp(func, alist) if alist first_pair = car(alist) first_value = car(first_pair) if func.call(first_value) first_pair else assp(func, cdr(alist)) end else false end end
car(z)
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# File lib/micro_kanren/lisp.rb, line 11 def car(z) ; z.call(-> (p, q) { p }) ; end
ccel?()
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# File lib/micro_kanren/lisp.rb, line 7 def ccel? ; true ; end
cdr(z)
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# File lib/micro_kanren/lisp.rb, line 12 def cdr(z) ; z.call(-> (p, q) { q }) ; end
cons(x, y)
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Returns a Cons cell that is also marked as such for later identification.
# File lib/micro_kanren/lisp.rb, line 5 def cons(x, y) -> (m) { m.call(x, y) }.tap do |func| func.instance_eval{ def ccel? ; true ; end } end end
cons?(d)
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# File lib/micro_kanren/lisp.rb, line 14 def cons?(d) d.respond_to?(:ccel?) && d.ccel? end
Also aliased as: pair?
length(list)
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# File lib/micro_kanren/lisp.rb, line 23 def length(list) list.nil? ? 0 : 1 + length(cdr(list)) end
lists_equal?(a, b)
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# File lib/micro_kanren/lisp.rb, line 73 def lists_equal?(a, b) if cons?(a) && cons?(b) lists_equal?(car(a), car(b)) && lists_equal?(cdr(a), cdr(b)) else a == b end end
lprint(node, cons_in_cdr = false)
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Converts Lisp
AST to a String. Algorithm is a recursive implementation of www.mat.uc.pt/~pedro/cientificos/funcional/lisp/gcl_22.html#SEC1238.
# File lib/micro_kanren/lisp.rb, line 56 def lprint(node, cons_in_cdr = false) if cons?(node) str = cons_in_cdr ? '' : '(' str += lprint(car(node)) if cons?(cdr(node)) str += ' ' + lprint(cdr(node), true) else str += ' . ' + lprint(cdr(node)) unless cdr(node).nil? end cons_in_cdr ? str : str << ')' else atom_string(node) end end
map(func, list)
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# File lib/micro_kanren/lisp.rb, line 19 def map(func, list) cons(func.call(car(list)), map(func, cdr(list))) if list end
procedure?(elt)
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We implement scheme cons cells as Procs. This function returns a boolean identically to the Scheme procedure? function to avoid false positives.
# File lib/micro_kanren/lisp.rb, line 29 def procedure?(elt) elt.is_a?(Proc) && !cons?(elt) end
Private Instance Methods
atom_string(node)
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# File lib/micro_kanren/lisp.rb, line 83 def atom_string(node) case node when NilClass, Array, String node.inspect else node.to_s end end