AC (HAC Ada Compiler) is a small, quick, open-source Ada compiler,
covering a subset of the Ada language. HAC is itself fully programmed
in Ada.

Web site: http://hacadacompiler.sf.net/

Source repositories:
#1 svn: https://sf.net/p/hacadacompiler/code/HEAD/tree/trunk/
#2 git: https://github.com/zertovitch/hac

* Main improvements since v.0.095:

- range checks on discrete subtype assignment (:=) and
conversion
- short-circuit logical operators: "and then", "or else"
- for S = Scalar subtype: S'First, S'Last, S'Succ, S'Pred, S'Pos,
S'Val, S'Image, S'Value, S'Range attributes
- for A = array object or array subtype: A'First [(N)],
A'Last [(N)], A'Range [(N)], A'Length [(N)] attributes
- "&", "<", ">", "=", "/=" operators defined for the String type
(additionally to HAL.VString type)
- CASE choices admit ranges
- forward declarations for subprograms

Enjoy!

Gautier

PS: for Windows there is an integrated editor that embeds HAC:
LEA: http://l-e-a.sf.net