Add from-optional function

coalton-lang · Dec 3, 2024 · eacb0df · eacb0df
1 parent 19965eb
commit eacb0df
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diff --git a/library/optional.lisp b/library/optional.lisp
@@ -7,6 +7,7 @@
    (#:cell #:coalton-library/cell)
    (#:iter #:coalton-library/iterator))
   (:export
+   #:from-optional
    #:from-some
    #:some?
    #:none?))
@@ -23,6 +24,13 @@
   ;; Optional
   ;;
 
+  (declare from-optional (:a -> (Optional :a) -> :a))
+  (define (from-optional def opt)
+    "Get the value of OPT, or return DEF if OPT is None."
+    (match opt
+      ((Some x) x)
+      ((None) def)))
+
   (declare from-some (String -> (Optional :a) -> :a))
   (define (from-some str opt)
     "Get the value of OPT, erroring with the provided string if it is None."

diff --git a/library/prelude.lisp b/library/prelude.lisp
@@ -130,10 +130,12 @@
 
   (:import-from
    #:coalton-library/optional
+   #:from-optional
    #:from-some
    #:some?
    #:none?)
   (:export
+   #:from-optional
    #:from-some
    #:some?
    #:none?)