CODEWITHSUNDEEP
prologlambda-calculus
Britishgoat
Britishgoat

Reputation: 23

lambda Calculus symbol syntax error prolog

I am trying to implement beta reduction, DCG, and lexicon in Prolog. When I tried to compile, it gave me a syntax error which is the operator @. How can I fix it?

beta(Exp,Exp):-
    atomic(Exp),
    !.

beta(lbd(V,F_body)@Exp,Result):-
    !,
    substitute(V,Exp,F_body,Result1),
    beta(Result1,Result).

beta(Exp,Result):-
    Exp=..ExpList,
    maplist(beta,ExpList,ResultList),
    Result=..ResultList.

s(SSem) --> np(NPSem), vp(VPSem),{var_replace(NPSem,NPSem1),beta(NPSem1@VPSem,SSem)}.

vp(VPSem) --> v(VSem), np(NPSem),{var_replace(VSem,VSem1),beta(VSem1@NPSem,VPSem)}.

np(lbd(p,p@john)) --> [john].

np(lbd(p,p@mary)) --> [mary].

v(lbd(s,lbd(x,s@lbd(y,likes(x,y))))) --> [likes].

Upvotes: 0

Views: 72

Answers (1)

mat
mat

Reputation: 40778

You can define @ as a binary operator, using, for example:

 :- op(500, xfy, @).

If you add this directive at the top of your program, it compiles without errors and warnings, and you can use (@)/2 as an infix operator from then on.

Example:

?- write_canonical(a@b@c).
@(a,@(b,c))

I leave choosing the suitable associativity for this operator as an exercise.

Upvotes: 1

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