Parens causing problems in function/pred application

[mlavrent]

Seems that Forge throws errors when we use parens instead of brackets for function application. Need to either enforce that fun/pred definitions only use brackets or that parens/brackets are interchangeable in this sense. See https://piazza.com/class/k47gct456or1u6?cid=275

[mlavrent]

Also:

• https://piazza.com/class/k47gct456or1u6?cid=253

[tnelson]

Looking at the Piazza thread for this, I believe the issue was that students were trying to use syntax like p(a) instead of p[a]. While the situation has improved, the errors could be better. Here are two examples:

#lang forge
sig A {}
pred p[a: A] {}
test expect { {some x: A | p(x)} is sat }

produces: x: unbound identifier at the use of x.

#lang forge
sig A {}
pred p[a: A] {}
test expect { {some x: A | {p(x)}} is sat }

produces: Element 1 of this block was an ill-formed predicate or helper function call. Check that the number of arguments given matches the declaration.

The latter indicates that, when enclosed in braces, Forge detects that predicate p is being used incorrectly. (Under the hood, >0-ary p is a Racket procedure. )