%ifndef MONAD_INC
%define MONAD_INC
%ifndef ALLOC_INC
%include "alloc.inc"
%endif

struc	MaybeMonad
mm_v:	resq 1
mm_e:	resb 1
endstruc

%macro	m_make	1-3	0,0
	;; %1 = Name
	;; %2 = Address of Structure
	;; %3 = Something > 0, Nothing = 0
	section .data
	align 8
m_%1:
	istruc MaybeMonad
	at mm_v, dq %2 ; The address of the MaybeMonad-wrapped structure
	at mm_e, db %3		  ; Something > 0, Nothing = 0
	iend
%endm

%macro	m_Just	1-3	0,0
	;; %1 = Name
	;; %2 = New Structure Address
	;; %3 = Something > 0, Nothing = 0
	%if %2 != 0
	lea	rax,	[rel %2]
	mov	qword [%1+mm_v],	rax
	%else
	mov	qword [%1+mm_v],	0
	%endif
	%if %3 != 0
	mov	byte [%1+mm_e],	%3
	%else
	mov	byte [%1+mm_e],	0
	%endif
	lea	rax,	[%1]
%endm

%macro	m_Nothing	1
	;; %1 = Name
	m_Just %1
%endm

%macro	m_return	1-2	rax
	m_Just	%1, %2, 1
%endm
	
%macro	m_bind	1-2	rax
	;; %1 = Callable Function with Single Argument, the Unwrapped MaybeMonad
	;; %2 = MaybeMonad
	;; m a -> (a -> m b) -> m b
	lea	rax,	[%2]
	mov	rcx,	rax
	mov	al,	byte [rcx + mm_e]
	cmp	al,	0
	je	%%exit
	mov	rax,	[rcx + mm_v]
	call	%1
%%exit:
%endmacro
	
%macro	m_call	1-2	rax
	;; %1 = Callable Function with Single Argument, the Unwrapped MaybeMonad
	;; %2 = MaybeMonad
	;; m a -> (a -> !) -> !
	lea	rax,	[%2]
	mov	rcx,	rax
	mov	al,	byte [rcx + mm_e]
	cmp	al,	0
	je	%%exit
	mov	rax,	[rcx + mm_v]
	call	%1
%%exit:
%endmacro

%macro	alloc_m	0
	alloc	MaybeMonad_size
%endm

%macro	free_m	0-1	rax
	free	%1,	MaybeMonad_size
%endm

%endif