diff options
| author |  John Cowan
| 2021-08-15 22:44:59 -0400 |
|---|---|---|
| committer | John Cowan
| 2021-08-15 22:44:59 -0400 |
| commit | cb6cae4950d0af111760d9abfc88aa03fb211f0c (patch) | |
| tree | b0dcc4e1dd506a4a31ab4abc1f51709eedd1e027 /srfi-225.html | |
| parent | MN-W review (diff) | |
unfold, new issues
Diffstat (limited to 'srfi-225.html')
| -rw-r--r-- | srfi-225.html | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/srfi-225.html b/srfi-225.html index b21acd1..678d840 100644 --- a/srfi-225.html +++ b/srfi-225.html @@ -34,17 +34,17 @@ of the object is. Such an object is called a <em>dictionary</em> in this SRFI.< <h2 id="issues">Issues</h2> -<p>dict-unfold: as you would think.</p> <p>dict=?, dict<?, etc. Compare dictionaries for equality, subset, etc. A value comparator is passed in.</p> -<p>dict-union(!), dict-intersection(!), etc. -Functional and linear-update versions of these operations.</p> +<p>dict-union(!), dict-intersection(!), dict-difference(!), dict-xor(!).</p> -<p>dict-range=(!), dict-range<(!), etc. Return subsets whose keys are =, <, etc.</p> +<p>dict-range=(!), dict-range<(!), etc. Return subsets whose keys are =, <, etc. +of a provided value.</p> -<p>-dict-fold/reverse (maybe)</p> +<p>dict-open-mapping, dict-closed mapping, dict-open-closed-mapping, dict-closed-open-mapping. +Returns subsets whose keys are in a certain interval specified by upper and lower bounds.</p> <p>dict-min-key, dict-max-key: Returns the smallest and largest key in the dictionary.</p> @@ -81,6 +81,17 @@ Consequently, previous examples don't affect later ones. <p>Returns an empty dictionary of the type described by the DTD using <em>comparator</em> to specify the dictionary's equality predicate and its ordering predicate and/or hash function.</p> <p>If the contents of <em>comparator</em> are inconsistent with the dictionary type, it is an error. If the dictionary type does not accept a comparator, <code>#f</code> should be passed instead.</p> +<p><code>(dict-unfold</code> <em>dtd comparator stop? mapper successor seed</em><code>)</code></p> +<p> +Create a new dictionary as if by <code>make-dictionary</code> using +<em>dtd</em> and <em>comparator</em>. If the result of applying +the predicate <em>stop?</em> to <em>seed</em> is true, return the dictionary. +Otherwise, apply the procedure <em>mapper</em> to <em>seed</em>. +<em>Mapper</em> returns two values, which are inserted into the dictionary +as the key and the value respectively. Then get a new seed by +applying the procedure <em>successor</em> to <em>seed</em>, and repeat +this algorithm. +</p> <h3 id="predicates">Predicates</h3> <p><code>(dictionary?</code> <em>dtd obj</em><code>)</code></p> <p>Returns <code>#t</code> if <em>obj</em> answers <code>#t</code> to the type predicate stored in the DTD, and <code>#f</code> otherwise.</p> |