▼scramble:   Assorted Utility Libraries
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result/  c
partition-results
8.16.0.4
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14 Results🔗ℹ

 (require scramble/result) package: scramble-lib

Added in version 0.3 of package scramble-lib.

This module defines a result type. In general, a result is either ok and carries a success value, or it is bad and carries a value representing failure.

Examples:
> (ok 5)             ; (Result Integer)

'#s(ok 5)

> (ok (ok 5))        ; (Result (Result Integer))

'#s(ok #s(ok 5))

> (ok 'hello)        ; (Result Symbol)

'#s(ok hello)

> (ok (list 1 2 3))  ; (Result (Listof Integer))

'#s(ok (1 2 3))

> (ok (bad 123))     ; (Result (Result _ Integer))

'#s(ok #s(bad 123))

struct

(struct ok (value)
    #:prefab)
  value : any/c
Struct type for wrapped OK results.

struct

(struct bad (value)
    #:prefab)
  value : any/c
Struct type for bad results.

procedure

(result? v) → boolean?

  v : any/c
Equivalent to (or (ok? v) (bad? v)).

procedure

(result/c ok-value/c [bad-value/c]) → contract?

  ok-value/c : contract?
  bad-value/c : contract? = any/c
A value result is accepted by (result/c ok-value/c bad-value/c) if

  • result is (ok v) and v is accepted by ok-value/c, or

  • result is (bad v) and v is accepted by bad-value/c.

procedure

(partition-results rs) → 
(listof X) (listof Y)
  rs : (listof (result/c X Y))
Returns the list of OK values and the list of bad values occurring in rs. The order of values is preserved.

Example:
> (partition-results (list (ok 1) (bad 2) (ok 3)))

'(1 3)

'(2)

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