README.html

<h2>What is in this directory (hs2stratego)</h2>
<div>
The code in this directory implements a simple translation of Haskell code
to the Stratego representation defined in ../../Plogic. There is one new
pfe command:

<pre>
    pfe stratego M
</pre>

For the time being, it translates a Haskell module M to a list of Decl (defined
below). Unsupported forms of declarations are ignored. The translation is
made before type checking.
<p>
The command <code>pfe prove</code>, which provided an earlier version of
the translation to Stratego, has been removed. The code is still available
in <a href="../Phugs/"><code>../Phugs</code</a>.
</div>

<h3>Files</h3>

<div>
<p>The subdirectory <code>AST</code> contains the Haskell implementation of the
abstract syntax in <code>../../Plogic</code>:</p>

<table>
<tr><th>File<th>Corresponds to
<tr><td>AST/StrategoPattern.hs		<td>Pattern.r
<tr><td>AST/StrategoProp.hs		<td>Prop.r, Pred.r
<tr><td>AST/StrategoTerm.hs		<td>Term.r
<tr><td>AST/StrategoType.hs		<td>Type.r
<tr><td>AST/StrategoDecl.hs		<td>a type for top-level declarations
<tr><td>AST/StrategoAST2.hs		<td>collects and re-exports all
</table>

<p>
This directory contains the translation functions and the code to hook
into the PFE framework.</p>

<table>
<tr><th>File<th>Purpose
<tr><td>StrategoCmds.hs			<td> hook it into the PFE framework
<tr><td>BaseStruct2Stratego2.hs		<td> base syntax translation
<tr><td>PropStruct2Stratego2.hs		<td> P-logic translation
<tr><td>Prop2Stratego2.hs		<td> knot-tying definitions
<tr><td>Flags.ghc                       <td> compiler flags for GHC
</table>
</div>
<h3>About the translation</h3>


<ul>
<li>A new data type for top-level declarations have been introduced,
see <a href="AST/StrategoDecl.hs">AST/StrategoDecl.hs</a>.
<li>
All top-level names are replaced with their original name (qualified name).
<li>
Function bindings and list comprehensions are simplified as in the
Haskell&nbsp;98 report.
<li>
The output is produced by using derived <code>Show</code> instances,
so these has to be an <strong>exact</strong> correspondence between
the Haskell data types in the AST directory and the data structures
expected in Stratego.
</ul>

<h3>Changes that should be made in the Stratego files</h3>

<ul>
<li>Some constructors names with hyphen have to be renamed:
    <ul>
    <li>     Prop-decl ==> PropDecl
    <li>     Lfp-Pred ==> LfpPred
    <li>     Gfp-Pred ==> GfpPred
    <li>     Pred-abs ==> PredAbs
    <li>     Pred-decl ==> PredDecl
    </ul>
<li>
The sort HBranch used in the constructor HCase isn't declared.
The result of the constructor HBranch is declared to be Term, but should
presumably be HBranch.
</ul>

<h3>Other things TODO</h3>

<ul>
<li>
HAbs takes a single pattern, but should probably take a list of patterns, since
      "\ p1 p2 -> e" is not the same as "\ p1 -> \ p2 -> e".

<li>
Make room for literals other than integers (strings, characters, fractional)
<li>
Make room for the record syntax (or translate it away).
<li>
Make sure the translation of types makes sense.
<li>
Make room for qualified types.
<li>
Make room for negation in patterns?
<li>
Make room for the equivalence connective <==>.
<li>
Are constructor applications assumed to be saturated?
<li>
Make room for type signatures in expressions, e.g. (+)::(Int->Int->Int)
<li>
...
</ul>
<hr>
<address>Authors: TH</address>
<address>Contact: <a href="http://www.cse.ogi.edu/~hallgren/">TH</address>