quicksort example, I64.parse, IO.write_file

src/std.zr

@@ -8,13 +8,13 @@ func print[x: String] : I64
 func print_i64[x: I64] : I64
     printf("%ld\n", x)
 
-func concat[a: String, b: String] : String
+func String.concat[a: String, b: String] : String
     let c: String = malloc(strlen(a) + strlen(b) + 1)
     strcpy(c, a)
     strcat(c, b)
     return c
 
-func substr[s: String, start: I64, length: I64] : String
+func String.substr[s: String, start: I64, length: I64] : String
     let out: String = malloc(length + 1)
     strlcpy(out, s + start, length + 1)
     return out
@@ -42,8 +42,17 @@ func IO.read_file[path: String]: String
 
     let n: I64 = fread(buffer, 1, size, file)
     String.set(buffer, n, 0)
+    fclose(file)
     return buffer
 
+func IO.write_file[path: String, content: String] : I64
+    let file: Ptr = fopen(path, "wb")
+    if !file
+        panic("failed to open file")
+
+    fwrite(content, 1, strlen(content), file)
+    fclose(file)
+
 func Char.to_i64[c: Char]: I64
     return c - 48
 
@@ -52,6 +61,9 @@ func I64.to_string[n: I64] : String
     sprintf(x, "%ld", n)
     return x
 
+func I64.parse[s: String] : I64
+    return strtol(s, 0, 0)
+
 func Math.gcd[a: I64, b: I64] : I64
     while b != 0
         let tmp: I64 = b