HAC Ada Compiler / News: Recent posts

🆕 Changes in this release:

• Improved some compilation diagnostics.
• Improved support for the String type.
• Added the 25 Advent of Code 2024 solutions as examples and regression tests (now 122 in total).
• Added new demos that output PDF files.

• Source stream is buffered: ~3x faster build on large sources
• HAT: added Create_Directory, Create_Path and Delete_Directory
• Added warning on variables read before they are written

• New target: HAC_Sys.Targets.AMD64_Windows_Console_FASM (embryonic, but produces a "hello world" executable)
• New target: HAC_Sys.Targets.Semantics for a smart editor (e.g. LEA) with helpers for auto-complete and navigation to declarations and bodies.
• New compilation diagnostics: warnings and notes.
• Added 25 new regression tests (Advent of Code)
• Several fixes

• You can use a loop's name for the exit statement: exit Loop_Name.
• You can exit multiple, nested, loops, by using exit Loop_Name.
• Ada semantics are better verified:
  • Array indexing (i)(j) (array of array) and (i, j) (multi-dimensional array) are no more treated as equivalent (this feature was a remnant of the Pascal syntax).
  • Separation between Type and Subtype declarations (anonymous types are allowed only in the few cases foreseen by the language).
  • Operators of the HAT package (+, -, & for strings) are visible without prefix only in the scope of a use HAT clause.

Note that correct Ada programs, in relation to the above points, were already accepted and parsed correctly by HAC before that change.... read more

• Added Virtual Machine Variables, another mean for exchanging data between the HAC program and the program hosting the VM.
• SmallAda's tasking is working again in its HAC reincarnation - at least, for some simple tasks.
• HAL becomes HAT (HAC Ada Toolbox), to avoid name collision with HAL = "Hardware Abstraction Layer".

New blog post titled "HAC as an embedded compiler" here.

• A program run by HAC can exchange data with the program running HAC, through dynamically registered call-backs

  • see package HAC_Sys.Interfacing and demos:
    src/apps/exchange_native_side.adb
    src/apps/exchange_hac_side.adb

• The compiler performs more compile-time range checks and optimizes away useless run-time checks when it is safe to do so.

• Check if all cases are covered in a CASE statement (required by Ada standard)
• Added compile-time range checks
• Added VM instructions that do the work of two or more other instructions
• Search and handling of WITH-ed sources is abstracted; source streams don't need to be files
• Command-line tool (hac[.exe]) has now a source search path via a new -I option and another one through the ADA_INCLUDE_PATH environment variable

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

Main improvements since v.0.0996:

• packages and subpackages are now supported
• modularity: packages and subprograms can be standalone
  library units, stored in individual files with
  GNAT's naming convention, and accessed from other units
  via the WITH clause
• validity checks were added for a better detection of
  uninitialized variables.... read more

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... read more

The main improvement is the modularity: HAC recursively compiles all units needed to build a main program.
Currently only procedures and functions bodies are supported as units - no packages yet, no separate specifications.

An example can be found in exm/unit_a.adb

A screenshot of that example:

... read more

• with and use context clauses are parsed properly (no more "placebo" parsing)
• use can be a local definition and has its real effect.
• HAC_Pack becomes HAL (HAC Ada Library)

HAC (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 repository #1: https://sf.net/p/hacadacompiler/code/HEAD/tree/
Source repository #2: https://github.com/zertovitch/hac

• Improvements:

  HAC_Integer (internal name in HAC_Sys.Defs), i.e. HAC's Integer
  type, is now 64 bit.
  HAC_Float (i.e. Real in HAC programs) has now System.Max_Digits
  digits accuracy.
  Added range constraints, like: subtype Answer_Range is Character range 'a' .. 'z'.
  Added membership test, like: x [not] in a .. b.
  Several additions to HAC_Pack.
  Better I/O error handling.
  The whole system (Compiler and VM run-time) builds on both
  GNAT and ObjectAda64.... read more

A screenshot of HAC in action (via the LEA editor) for the Advent of Code:

More details here.

Changes since v.0.07:

0.071
Discrete type range is stored in type definition; "subtype T1 is T2;"

0.072
Subtype_Indication (e.g. "for B in Boolean loop", "array (States) of Prob")
https://gautiersblog.blogspot.com/2020/06/hac-v0072-subtype-indication.html

0.073
The VM can be aborted via the Feedback procedure

0.074
Types: Time and Duration

0.075
Added Ada.Calendar-like functions
https://gautiersblog.blogspot.com/2020/10/hac-v0075-time-functions-goodies-for.html... read more

Errors are now propagated by HAC, as expected, down the call stack.
You get by default a detailed trace-back, like the following one. HAC's output is:

HAC VM: raised Constraint_Error
Out of range
Trace-back locations:
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift.Shift_n_add at line 18
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift at line 23
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift.Shift_n_add at line 16
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift at line 23
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift.Shift_n_add at line 16
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift at line 23
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift.Shift_n_add at line 16
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift at line 23
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift.Shift_n_add at line 16
exception_04.adb: Exception_04.Nest.NTF.Add_n_shift at line 23
exception_04.adb: Exception_04.Nest.NTF at line 27
exception_04.adb: Exception_04.Nest at line 34
exception_04.adb: Exception_04 at line 42... read more

As in the title!
An example here (exm/file_copy.adb):

with HAC_Pack;  use HAC_Pack;

procedure File_Copy is
  s : VString;
  f1, f2 : File_Type;
begin
  Open (f1, "file_copy.adb");
  Create (f2, "file_copy.txt");
  while not End_Of_File (f1) loop
    Get_Line (f1, s);
    Put_Line (f2, s);
  end loop;
  Close (f1);
  Close (f2);
end File_Copy;

Recent changes:

Rev.	Ver.	Fix?	Fix or improvement	Details, remarks	Date
130			Support for "Label: loop .. end loop Label;"		18.04.2020
138			Enumerated types can be used for CASE statements		22.04.2020
160		0.04	Added VString (variable-size string)		02.05.2020
161		0.041	VString: concatenation with "&"		02.05.2020
163		0.042	Command-line arguments	Argument_Count, Argument (the latter returns a VString)	02.05.2020
164		0.043	VString: added comparison operators, Element, Length, Slice		03.05.2020
168		0.044	VString: added Index, "*", Trim; added Get_Env and Set_Env		04.05.2020
171			VString: added Shell_Execute, Index (VString, String), Image, Integer_Value, Float_Value		06.05.2020
172		0.05	VString: Get_Line		06.05.2020

Recent changes:

Rev.	Ver.	Fix?	Fix or improvement	Details, remarks	Date
92			Implemented first explicit type conversion (Integer to Float)		31.03.2020
101		Fix	Evaluation of enum values in arrays and records was wrong		04.04.2020
104		Fix	Unary minus for float values (was ignored)	Added opcode: k_Unary_MINUS_Float	04.04.2020
108			HAC's default floating-point type is now double-precision and is called Real	Internal name in the HAC system: type HAC_Float is digits 15;	05.04.2020
110			HAC is now forbidding type coercion (implicit type conversion)	Coercion was only int -> float	06.04.2020
112			Test program HAC_Test is now THE command-line tool around HAC: HAX		08.04.2020
120			Support for typed constants		12.04.2020
121			Read-only mode for typed constants, "in" parameters, "for" loop variables		12.04.2020
123		Fix	Enumeration literals begin with position 0 (was 1)		13.04.2020
124			Enumerated types can be used for FOR control variables		13.04.2020
128		Fix	Only jump instructions are patched after IF or LOOP statements		16.04.2020
129	0.03		"Assembler" dump	From command-line: hax -a main.adb	17.04.2020

Some effort has been put to stabilize the compiler when confronted to erroneous code.