Josh's questions

export const identity = (a) => a
export const add = (a,b) => a+b
export const sub = (a,b) => a-b
export const mul = (a,b) => a*b
export const identityf = (a) => (() => a)
export const addf = (a) => ((b) => a+b)
export const curry = (f,b) => ((a) => f(a,b))
export const curryr = (f,b) => ((a) => f(a,b))
export const liftf = (f) => ((a) => curry(f,a))
export const twice = (f) => ((a) => f(a,a))
export const reverse = (f) => ((a,b)=>f(b,a))
export const composeu = (f1,f2) => ((a) => f2(f1(a)))
export const composeb = (f1, f2) => ((a,b,c)=>f2(f1(a,b), c))
export const limit = (f1, a) => ((...b) => {
  if(a <= 0) return;
  a = a-1;
  return f1(...b);
})
export const from = (a) => ( () => {
  a = a+1;
  return a-1;
})
export const to = (f1, v) => ( () => {
  const result = f1();
  if(result >= v) return;
  return result;
})
export const thru = (f1, v) => {
  return () => {
    const result = f1();
    if(result > v) return;
    return result;
  };
}
export const fromTo = (a,b) => {
  return () => {
    a += 1;
    if(a > b) return;
    return a-1;
  }
}
export const element = (arr, fn=fromTo(0, arr.length)) => {
  return () => {
    const i = fn();
    if(i || i=== 0) return arr[i];
  }
}
export const collect = (f, arr) => {
  return () => {
    const v = f();
    if(v || v === 0)
      arr.push(v);
    return v;
  }
}
export const filter = (f1,f2) => {
  return () => {
    let v = f1();
    while(v && !f2(v)) {
      v = f1();
    }
    return v;
  }
}
export const concat = (f1, f2) => {
  return () => {
    let v = f1();
    if(v !== undefined) {
      return v;
    }
    v = f2();
    if(v !== undefined) {
      return v;
    }
  }
}