add string functions

bootstrap.php

@@ -20,6 +20,7 @@ function ml_get_lisp(): array
     (new MadLisp\Lib\Collections())->register($env);
     (new MadLisp\Lib\Compare())->register($env);
     (new MadLisp\Lib\Math())->register($env);
+    (new MadLisp\Lib\Strings())->register($env);
     (new MadLisp\Lib\Types())->register($env);
 
     return [$lisp, $env];

src/Lib/Collections.php

@@ -6,6 +6,7 @@ use MadLisp\CoreFunc;
 use MadLisp\Env;
 use MadLisp\Func;
 use MadLisp\Hash;
+use MadLisp\MadLispException;
 use MadLisp\MList;
 use MadLisp\Seq;
 use MadLisp\Util;
@@ -39,9 +40,11 @@ class Collections implements ILib
             function ($a) {
                 if ($a instanceof Collection) {
                     return $a->count();
-                } else {
+                } elseif (is_string($a)) {
                     return strlen($a);
                 }
+
+                throw new MadLispException('len required string or collection as argument');
             }
         ));
 

src/Lib/Strings.php

@@ -0,0 +1,46 @@
+<?php
+namespace MadLisp\Lib;
+
+use MadLisp\CoreFunc;
+use MadLisp\Env;
+use MadLisp\MList;
+
+class Strings implements ILib
+{
+    public function register(Env $env): void
+    {
+        $env->set('trim', new CoreFunc('trim', 'Remove whitespace from beginning and end of string.', 1, 1,
+            fn (string $a) => trim($a)
+        ));
+
+        $env->set('upcase', new CoreFunc('upcase', 'Return string in upper case.', 1, 1,
+            fn (string $a) => strtoupper($a)
+        ));
+
+        $env->set('locase', new CoreFunc('locase', 'Return string in lower case.', 1, 1,
+            fn (string $a) => strtolower($a)
+        ));
+
+        $env->set('substr', new CoreFunc('substr', 'Return substring starting from index as second argument and length as optional third argument.', 2, 3,
+            function (string $a, int $i, ?int $l = null) {
+                if ($l === null) {
+                    return substr($a, $i);
+                } else {
+                    return substr($a, $i, $l);
+                }
+            }
+        ));
+
+        $env->set('split', new CoreFunc('split', 'Split the second argument by the first argument into a list.', 2, 2,
+            fn (string $a, string $b) => new MList(explode($a, $b))
+        ));
+
+        $env->set('join', new CoreFunc('join', 'Join the remaining arguments together by using the first argument as glue.', 1, -1,
+            fn (string $a, ...$b) => implode($a, $b)
+        ));
+
+        $env->set('format', new CoreFunc('format', 'Format the remaining arguments as string specified by the first argument.', 1, -1,
+            fn (string $a, ...$b) => sprintf($a, ...$b)
+        ));
+    }
+}