From 03a83abfbb805522b7cc2cd8a4f03e3d52963a4b Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Wed, 10 Dec 2025 11:26:04 -0800
Subject: [PATCH] [str] add capitalize and titlecase

---
 src/prelude/str.ts                                   | 10 ++++++++++
 src/prelude/tests/prelude.test.ts                    | 12 ++++++++++++
 .../server/src/metadata/prelude-completions.ts       | 10 ++++++++++
 3 files changed, 32 insertions(+)

diff --git a/src/prelude/str.ts b/src/prelude/str.ts
index ec688ae..3c9f17c 100644
--- a/src/prelude/str.ts
+++ b/src/prelude/str.ts
@@ -28,6 +28,16 @@ export const str = {
   },
   'pad-start': (str: string, length: number, pad: string = ' ') => String(str ?? '').padStart(length, pad),
   'pad-end': (str: string, length: number, pad: string = ' ') => String(str ?? '').padEnd(length, pad),
+  capitalize: (str: string) => {
+    const s = String(str ?? '')
+    return s.charAt(0).toUpperCase() + s.slice(1).toLowerCase()
+  },
+  titlecase: (s: string) => {
+    return String(s ?? '')
+      .split(' ')
+      .map(str.capitalize)
+      .join(' ')
+  },
   lines: (str: string) => String(str ?? '').split('\n'),
   chars: (str: string) => String(str ?? '').split(''),
 
diff --git a/src/prelude/tests/prelude.test.ts b/src/prelude/tests/prelude.test.ts
index 3db92e6..b297b6a 100644
--- a/src/prelude/tests/prelude.test.ts
+++ b/src/prelude/tests/prelude.test.ts
@@ -16,6 +16,18 @@ describe('string operations', () => {
     await expect(`str.trim '\\n\\thello\\t\\n'`).toEvaluateTo('hello')
   })
 
+  test('capitalize makes first char uppercase', async () => {
+    await expect(`str.capitalize 'hello'`).toEvaluateTo('Hello')
+    await expect(`str.capitalize 'HELLO'`).toEvaluateTo('Hello')
+    await expect(`str.capitalize 'hello world'`).toEvaluateTo('Hello world')
+  })
+
+  test('titlecase capitalizes each word', async () => {
+    await expect(`str.titlecase 'hello world'`).toEvaluateTo('Hello World')
+    await expect(`str.titlecase 'HELLO WORLD'`).toEvaluateTo('Hello World')
+    await expect(`str.titlecase 'the quick brown fox'`).toEvaluateTo('The Quick Brown Fox')
+  })
+
   test('split divides string by separator', async () => {
     await expect(`str.split 'a,b,c' ','`).toEvaluateTo(['a', 'b', 'c'])
     await expect(`str.split 'hello' ''`).toEvaluateTo(['h', 'e', 'l', 'l', 'o'])
diff --git a/vscode-extension/server/src/metadata/prelude-completions.ts b/vscode-extension/server/src/metadata/prelude-completions.ts
index 7985daa..621bfeb 100644
--- a/vscode-extension/server/src/metadata/prelude-completions.ts
+++ b/vscode-extension/server/src/metadata/prelude-completions.ts
@@ -739,6 +739,16 @@ export const completions = {
         "pad"
       ]
     },
+    "capitalize": {
+      "params": [
+        "str"
+      ]
+    },
+    "titlecase": {
+      "params": [
+        "s"
+      ]
+    },
     "lines": {
       "params": [
         "str"