1 files changed, 51 insertions, 0 deletions
diff --git a/std/default/format.pk b/std/default/format.pk
new file mode 100644
index 0000000..c7d7ab8
--- /dev/null
+++ b/std/default/format.pk
@@ -0,0 +1,51 @@
+## std/format: Niceties around printing and debugging.
+## This module is imported by default.
+
+## The Display interface. Any type implementing `str` is printable.
+## Any type that is Display must also implement Debug.
+pub type Display = interface
+  str(Self): str
+  dbg(Self): str
+
+## The Debug interface. Broadly implemented for every type with magic,
+## types can (and should) override the generic implementations.
+pub type Debug = interface
+  dbg(Self): str
+
+## Prints all of its arguments to the command line.
+pub func print(params: varargs[Display]) =
+  stdout.write(params.map(x => x.str).join(" "), "\n")
+
+## Prints all of its arguments to the command line, in Debug form.
+pub func dbg(params: varargs[Debug]) =
+  stdout.write(params.map(x => x.dbg).join(" "), "\n")
+
+## A dummy implementation of the Display interface for strings.
+pub func str(self: str): str = self
+## An implementation of the Debug interface for strings.
+pub func dbg(self: str): str = "\"" & self & "\""
+
+## An implementation of the Debug interface for all structs.
+## Uses the special `struct` typeclass.
+pub func dbg(self: struct): str =
+  "{" & self.fields.map(field => field.id & field.value.dbg) & "}"
+
+## An implementation of the Debug interface for all tuples.
+## Uses the special `tuple` typeclass.
+pub func dbg(self: tuple): str =
+  result &= "("
+  for i, field in self.fields.enumerate():
+    result &= field.id.map(id => id & " = ").get_or("")
+    if i != self.fields.len:
+      result &= ", "
+  result &= ")"
+
+## An implementation of the Debug interface for all arrays and lists.
+pub func dbg(self: Iter[Debug]): str =
+  "[" & self.map(x => x.str).join(", ") & "]"
+
+## The fmt macro. Builds a formatted string from its arguments.
+pub macro fmt(formatted: static[str], args: varargs[Display]) =
+  # if not formatted of String:
+  #   macro_error("fmt must take a static string parameter!")
+  ...