Add paragraph to introduction about HDLs embedded in Haskell

diff --git a/cλash.lhs b/cλash.lhs
index 9ec58f1248b54babada9374f6ba49bab47062829..ab3c8e258d81f4b8a8aa19d35ae202d9106dc2f2 100644 (file)
--- a/cλash.lhs
+++ b/cλash.lhs
@@ -473,12 +473,29 @@ level, a great number of approaches based on functional languages has been
 proposed \cite{T-Ruby,Hydra,HML2,Hawk1,Lava,ForSyDe1,Wired,reFLect}. The idea 
 of using functional languages started in the early 1980s \cite{Cardelli1981,
 muFP,DAISY,FHDL}, a time which also saw the birth of the currently popular 
 proposed \cite{T-Ruby,Hydra,HML2,Hawk1,Lava,ForSyDe1,Wired,reFLect}. The idea 
 of using functional languages started in the early 1980s \cite{Cardelli1981,
 muFP,DAISY,FHDL}, a time which also saw the birth of the currently popular 

-hardware description languages such as \VHDL.
+hardware description languages such as \VHDL. What gives functional languages 
+as hardware description languages their merits is the fact that basic 
+combinatorial circuits are equivalent to mathematical function, and that 
+functional languages lend themselves very well to describe and compose these 
+mathematical functions.
+
+In an attempt to decrease the amount of work involved with creating all the 
+required tooling, such as parsers and type-checkers, many functional hardware 
+description languages are embedded as a domain specific language inside the 
+functional language Haskell \cite{Hydra,Hawk1,Lava,ForSyDe1,Wired}. What this 
+means is that a developer is given a library of Haskell functions and types 
+that together form the language primitives of the domain specific language. 
+Using these functions, the designer does not only describes a circuit, but 
+actually builds a large domain-specific datatype which can be further 
+processed by an embedded compiler. This compiler actually runs in the same 
+environment as the description; as a result compile-time and run-time become 
+hard to define, as the embedded compiler is usually compiled by the same 
+Haskell compiler as the circuit description itself.
+
+The approach taken in this research is not to make another domain specific 
+language embedded in Haskell, but to use (a subset) of the Haskell language 
+itself to be used as hardware description language. 

 
 

-What gives functional languages as hardware description languages their merits 
-is the fact that basic combinatorial circuits are equivalent to mathematical 
-function, and that functional languages lend themselves very well to describe 
-and compose these mathematical functions.

 \section{Hardware description in Haskell}
 
   \subsection{Function application}
 \section{Hardware description in Haskell}
 
   \subsection{Function application}


@@ -511,7 +528,7 @@ mac a b c = add (mul a b) c
 
     TODO: Pretty picture
 
 
     TODO: Pretty picture
 

-  \subsection{Choices }
+  \subsection{Choices}

     Although describing components and connections allows describing a
     lot of hardware designs already, there is an obvious thing missing:
     choice. We need some way to be able to choose between values based
     Although describing components and connections allows describing a
     lot of hardware designs already, there is an obvious thing missing:
     choice. We need some way to be able to choose between values based


@@ -800,7 +817,7 @@ type Sum = (SumC, Bit, Word, Word)
     This approach makes the state of a function very explicit: which variables 
     are part of the state is completely determined by the type signature. This 
     approach to state is well suited to be used in combination with the 
     This approach makes the state of a function very explicit: which variables 
     are part of the state is completely determined by the type signature. This 
     approach to state is well suited to be used in combination with the 

-    existing code and language features, such as all the choice elements, as 
+    existing code and language features, such as all the choice constructs, as 

     state values are just normal values.
 \section{\CLaSH\ prototype}
 
     state values are just normal values.
 \section{\CLaSH\ prototype}
 


@@ -851,11 +868,11 @@ polymorphic components. Note that those types still require an explicit
 generic map, whereas type-inference and type-specialization are implicit in 
 \CLaSH.
 
 generic map, whereas type-inference and type-specialization are implicit in 
 \CLaSH.
 

-Wired~\cite{Wired},, T-Ruby~\cite{T-Ruby}, Hydra~\cite{Hydra}. 
-
-A functional language designed specifically for hardware design is 
-$re{\mathit{FL}}^{ect}$~\cite{reFLect}, which draws experience from earlier 
-language called \acro{FL}~\cite{FL} to la
+% Wired~\cite{Wired},, T-Ruby~\cite{T-Ruby}, Hydra~\cite{Hydra}. 
+% 
+% A functional language designed specifically for hardware design is 
+% $re{\mathit{FL}}^{ect}$~\cite{reFLect}, which draws experience from earlier 
+% language called \acro{FL}~\cite{FL} to la

 
 % An example of a floating figure using the graphicx package.
 % Note that \label must occur AFTER (or within) \caption.
 
 % An example of a floating figure using the graphicx package.
 % Note that \label must occur AFTER (or within) \caption.