derivedFilters.ts

//greater than or equal
export const gte = <A, K extends keyof A>(field: K, val: A[K]): Filter<A> =>
  or(greater(field, val), equals(field, val));

//less than or equal
export const lte = <A, K extends keyof A>(field: K, val: A[K]): Filter<A> =>
  or(less(field, val), equals(field, val));

//combine 1 to many filters returning true if all are true (and)
export const all = <A>(...dsl: Filter<A>[]): Filter<A> =>
  dsl.reduce((p, c) => and(p, c));

//combine 1 to many filters returning true if any are true (or)
export const any = <A>(...dsl: Filter<A>[]): Filter<A> =>
  dsl.reduce((p, c) => or(p, c));

//essentially sql's in operator.  Given a field and a collection of values
//this returns true if any are true.
export const oneOf = <A, K extends keyof A>(field: keyof A, ...vals: A[K][]): Filter<A> =>
  any(...vals.map(x => equals(field, x)));