85 lines
1.5 KiB
Markdown
85 lines
1.5 KiB
Markdown
# rusty-wam
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An implementation of the Warren Abstract Machine in Rust, done
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according to the progression of languages in [Warren's Abstract
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Machine: A Tutorial
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Reconstruction](http://wambook.sourceforge.net/wambook.pdf), ending in
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pure Prolog.
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## Progress
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The language L2 is implemented as a simple REPL. It supports
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unification on queries without backtracking, where rules and facts are
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limited to a single name/arity pairing, in the familiar Prolog
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syntax. No data types apart from atoms are currently supported.
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An example of the level of interaction currently supported is:
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```
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l2> p(Z, Z).
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l2> ?- p(Z, Z).
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yes
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l2> ?- p(Z, z).
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yes
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l2> ?- p(Z, w).
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yes
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l2> clouds(are, nice).
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l2> ?- p(z, w).
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no
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l2> ?- p(w, w).
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yes
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l2> ?- clouds(Z, Z).
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no
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l2> ?- clouds(Z, W).
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yes
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l2> ?- clouds(are, W).
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yes
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l2> ?- clouds(W, nice).
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yes
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l2> ?- clouds(nice, are).
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no
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l2> ?- p(Z, h(Z, W), f(W)).
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no
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l2> p(Z, h(Z, W), f(W)).
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l2> ?- p(z, h(z, z), f(w)).
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no
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l2> ?- p(z, h(z, w), f(w)).
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yes
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l2> ?- p(Z, h(z, W), f(w)).
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yes
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l2> ?- p(z, h(Z, w), f(w)).
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yes
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l2> ?- p(Z, h(Z, w), f(Z)).
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yes
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l2> ?- p(z, h(Z, w), f(Z)).
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no
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l2> p(f(X), h(Y, f(a)), Y).
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l2> ?- p(Z, h(Z, W), f(W)).
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yes
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l2> p(X, Y) :- q(X, Z), r(Z, Y).
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l2> q(q, s).
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l2> r(s, t).
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l2> ?- p(X, Y).
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yes
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l2> ?- p(q, t).
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yes
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l2> ?- p(t, q).
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no
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l2> ?- p(q, T).
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yes
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l2> ?- p(Q, t).
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yes
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l2> ?- p(t, t).
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no
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l2> quit
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```
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## Occurs check
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There's no occurs check, so cyclic terms do unify:
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```
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l2> p(W, W).
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l2> ?- p(f(f(W)), W).
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yes
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``` |