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semanticParsing.wppl
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semanticParsing.wppl
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var literalListener = function(utterance, qud) {
Enumerate(function() {
var m = meaning(utterance)
var world = worldPrior(3, m)
factor(m(world) ? 0 : -Infinity)
return qud(world)
})
}
var makeObj = function() {
return {blond: flip(0.5), nice: flip(0.5), tall: flip(0.5)}
}
var worldPrior = function(nObjLeft, meaningFn, worldSoFar, prevFactor) {
var worldSoFar = worldSoFar == undefined ? [] : worldSoFar
var prevFactor = prevFactor == undefined ? 0 : prevFactor
if (nObjLeft == 0) {
factor(-prevFactor)
return worldSoFar
} else {
var newObj = makeObj()
var newWorld = worldSoFar.concat([newObj])
var newFactor = meaningFn(newWorld) ? 0 : -100
factor(newFactor - prevFactor)
return worldPrior(nObjLeft - 1, meaningFn, newWorld, newFactor)
}
}
var meaning = function(utterance) {
return combineMeanings(
filter(function(m) {return !(m.sem == undefined)},
map(function(w) {return lexicalMeaning(w)},
utterance.split(' '))))
}
var lexicalMeaning = function(word) {
var wordMeanings = {
'blond' : {
sem: function(world) {return function(obj) {return obj.blond}},
syn: {dir: 'L', int: 'NP', out: 'S'} },
'nice' : {
sem: function(world) {return function(obj) {return obj.nice}},
syn: {dir: 'L', int: 'NP', out: 'S'} },
'Bob' : {
sem: function(world) {return find(function(obj) {return obj.name == 'Bob'}, world)},
syn: 'NP' },
'some' : {
sem: function(world) {return function(P) {return function(Q) {return filter(Q, filter(P, world)).length > 0}}},
syn: {dir: 'R',
int: {dir: 'L', int: 'NP', out: 'S'},
out: {dir: 'R',
int: {dir: 'L', int: 'NP', out: 'S'},
out: 'S'}} },
'all' : {
sem: function(world) {
return function(P) {
return function(Q) {
return filter(neg(Q), filter(P, world)).length == 0}}},
syn: {dir: 'R',
int: {dir: 'L', int: 'NP', out: 'S'},
out: {dir: 'R',
int: {dir: 'L', int: 'NP', out: 'S'},
out: 'S'}} }
}
var meaning = wordMeanings[word];
return meaning == undefined ? {sem: undefined, syn: ''} :meaning;
}
// We use this helper function to negate a predicate above:
var neg = function(Q) {
return function(x) {return !Q(x)}
}
// Assume that both f and a will give their actual semantic value
// after being applied to a world. make a new meaning that passes on
// world arg.
var applyWorldPassing = function(f, a) {
return function(w) {return f(w)(a(w))}
}
var combineMeaning = function(meanings) {
var possibleComb = canApply(meanings, 0)
var i = possibleComb[randomInteger(possibleComb.length)]
var s = meanings[i].syn
if (s.dir == 'L') {
var f = meanings[i].sem
var a = meanings[i - 1].sem
var newmeaning = {sem: applyWorldPassing(f, a), syn: s.out}
return meanings.slice(0, i - 1).concat([newmeaning]).concat(meanings.slice(i + 1))
}
if (s.dir == 'R') {
var f = meanings[i].sem
var a = meanings[i + 1].sem
var newmeaning = {sem: applyWorldPassing(f, a), syn: s.out}
return meanings.slice(0, i).concat([newmeaning]).concat(meanings.slice(i + 2))
}
}
//make a list of the indexes that can (syntactically) apply.
var canApply = function(meanings, i) {
if (i == meanings.length) {
return []
}
var s = meanings[i].syn
if (s.hasOwnProperty('dir')) { //a functor
var a = ((s.dir == 'L') ? syntaxMatch(s.int, meanings[i - 1].syn) : false) |
((s.dir == 'R') ? syntaxMatch(s.int, meanings[i + 1].syn) : false)
if (a) {return [i].concat(canApply(meanings, i + 1))}
}
return canApply(meanings, i + 1)
}
// The syntaxMatch function is a simple recursion to
// check if two syntactic types are equal.
var syntaxMatch = function(s, t) {
return !s.hasOwnProperty('dir') ? s == t :
s.dir == t.dir & syntaxMatch(s.int, t.int) & syntaxMatch(s.out, t.out)
}
// Recursively do the above until only one meaning is
// left, return it's semantics.
var combineMeanings = function(meanings) {
return meanings.length == 1 ? meanings[0].sem : combineMeanings(combineMeaning(meanings))
}
literalListener(
'all blond people are nice',
function(world) {return sum(map(function(x) {return x['nice']}, world))});