Function tract_dim_eval 

pub unsafe extern "C" fn tract_dim_eval(
    dim: *const TractDim,
    nb_symbols: usize,
    symbols: *const *const i8,
    values: *const i64,
    result: *mut *mut TractDim,
) -> TRACT_RESULT

Substitute symbols by the provided values in the Dim, generating a new one.