1 let (++) f g x = f (g x);;
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4 let print_hline = Console.print_hline;;
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15 let rec aux l1 l2 t1 t2 = match t1, t2 with
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16 | L t1, L t2 -> aux l1 l2 t1 t2
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17 | L t1, t2 -> aux l1 (l2+1) t1 t2
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18 | t1, L t2 -> aux (l1+1) l2 t1 t2
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19 | V a, V b -> a + l1 = b + l2
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20 | A(t1,t2), A(u1,u2) -> aux l1 l2 t1 u1 && aux l1 l2 t2 u2
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30 ; sigma : (var * t) list (* substitutions *)
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31 ; stepped : var list
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34 exception Done of (var * t) list (* substitution *);;
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35 exception Fail of int * string;;
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38 let string_of_bvar =
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39 let bound_vars = ["x"; "y"; "z"; "w"; "q"] in
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40 let bvarsno = List.length bound_vars in
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41 fun nn -> if nn < bvarsno then List.nth bound_vars nn else "x" ^ (string_of_int (nn - bvarsno + 1)) in
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42 let rec string_of_term_w_pars level = function
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43 | V v -> if v >= level then "`" ^ string_of_int (v-level) else
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44 string_of_bvar (level - v-1)
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46 | L _ as t -> "(" ^ string_of_term_no_pars level t ^ ")"
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48 and string_of_term_no_pars_app level = function
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49 | A(t1,t2) -> string_of_term_no_pars_app level t1 ^ " " ^ string_of_term_w_pars level t2
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50 | _ as t -> string_of_term_w_pars level t
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51 and string_of_term_no_pars level = function
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52 | L t -> "λ" ^ string_of_bvar level ^ ". " ^ string_of_term_no_pars (level+1) t
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53 | _ as t -> string_of_term_no_pars_app level t
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54 in string_of_term_no_pars 0
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57 let string_of_problem p =
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59 "[stepped] " ^ String.concat " " (List.map string_of_int p.stepped);
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60 "[DV] " ^ string_of_t p.div;
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61 "[CV] " ^ string_of_t p.conv;
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63 String.concat "\n" lines
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66 let problem_fail p reason =
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67 print_endline "!!!!!!!!!!!!!!! FAIL !!!!!!!!!!!!!!!";
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68 print_endline (string_of_problem p);
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69 raise (Fail (-1, reason))
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72 let freshvar ({freshno} as p) =
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73 {p with freshno=freshno+1}, freshno+1
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78 | A(t,_) -> is_inert t
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83 let is_var = function V _ -> true | _ -> false;;
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84 let is_lambda = function L _ -> true | _ -> false;;
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86 let rec get_inert = function
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88 | A(t, _) -> let hd,args = get_inert t in hd,args+1
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92 let rec subst level delift sub =
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94 | V v -> if v = level + fst sub then lift level (snd sub) else V (if delift && v > level then v-1 else v)
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95 | L t -> L (subst (level + 1) delift sub t)
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97 let t1 = subst level delift sub t1 in
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98 let t2 = subst level delift sub t2 in
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101 and mk_app t1 t2 = match t1 with
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102 | B | _ when t2 = B -> B
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103 | L t1 -> subst 0 true (0, t2) t1
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108 | V m -> V (if m >= lev then m + n else m)
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109 | L t -> L (aux (lev+1) t)
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110 | A (t1, t2) -> A (aux lev t1, aux lev t2)
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114 let subst = subst 0 false;;
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116 let subst_in_problem (sub: var * t) (p: problem) =
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117 print_endline ("-- SUBST " ^ string_of_t (V (fst sub)) ^ " |-> " ^ string_of_t (snd sub));
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119 div=subst sub p.div;
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120 conv=subst sub p.conv;
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121 stepped=(fst sub)::p.stepped;
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122 sigma=sub::p.sigma}
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125 let get_subterm_with_head_and_args hd_var n_args =
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126 let rec aux lev = function
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128 | L t -> aux (lev+1) t
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130 let hd_var', n_args' = get_inert t1 in
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131 if hd_var' = hd_var + lev && n_args <= 1 + n_args'
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132 then Some (lift ~-lev t)
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133 else match aux lev t2 with
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134 | None -> aux lev t1
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135 | Some _ as res -> res
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140 print_endline (string_of_problem p); (* non cancellare *)
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141 if p.conv = B then problem_fail p "p.conv diverged";
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142 if p.div = B then raise (Done p.sigma);
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143 if not (is_inert p.div) then problem_fail p "p.div converged"
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146 let print_cmd s1 s2 = print_endline (">> " ^ s1 ^ " " ^ s2);;
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148 (* eat the arguments of the divergent and explode.
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149 It does NOT perform any check, may fail if done unsafely *)
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151 print_cmd "EAT" "";
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152 let var, n = get_inert p.div in
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156 else L (aux (m-1) t) in
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157 let subst = var, aux n B in
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158 let p = subst_in_problem subst p in
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162 (* step on the head of div, on the k-th argument, with n fresh vars *)
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164 let var, _ = get_inert p.div in
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165 print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")");
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166 let rec aux' p m t =
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170 let p, v = freshvar p in
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171 let p, t = aux' p (m-1) t in
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172 p, A(t, V (v + k + 1)) in
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173 let p, t = aux' p n (V 0) in
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174 let rec aux' m t = if m < 0 then t else A(aux' (m-1) t, V (k-m)) in
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178 else L (aux (m-1) t) in
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180 let subst = var, t in
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181 let p = subst_in_problem subst p in
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186 let rec aux level = function
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187 | Parser_andrea.Lam t -> L (aux (level + 1) t)
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188 | Parser_andrea.App (t1, t2) ->
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189 if level = 0 then mk_app (aux level t1) (aux level t2)
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190 else A(aux level t1, aux level t2)
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191 | Parser_andrea.Var v -> V v
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192 in let (tms, free) = Parser_andrea.parse_many strs
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193 in (List.map (aux 0) tms, free)
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196 let problem_of div conv =
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198 let all_tms, var_names = parse ([div; conv]) in
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199 let div, conv = List.hd all_tms, List.hd (List.tl all_tms) in
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200 let varno = List.length var_names in
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201 let p = {orig_freshno=varno; freshno=1+varno; div; conv; sigma=[]; stepped=[]} in
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202 (* activate bombs *)
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204 let subst = Util.index_of "BOMB" var_names, L B in
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205 subst_in_problem subst p
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206 with Not_found -> p in
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207 (* initial sanity check *)
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211 let exec div conv cmds =
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212 let p = problem_of div conv in
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214 problem_fail (List.fold_left (|>) p cmds) "Problem not completed"
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219 let inert_cut_at n t =
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224 let k', t' = aux t1 in
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225 if k' = n then n, t'
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227 | _ -> assert false
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231 let find_eta_difference p t n_args =
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232 let t = inert_cut_at n_args t in
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233 let rec aux t u k = match t, u with
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234 | V _, V _ -> assert false (* div subterm of conv *)
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235 | A(t1,t2), A(u1,u2) ->
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236 if not (eta_eq t2 u2) then (print_endline((string_of_t t2) ^ " <> " ^ (string_of_t u2)); k)
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237 else aux t1 u1 (k-1)
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238 | _, _ -> assert false
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239 in aux p.div t n_args
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242 let rec no_leading_lambdas = function
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243 | L t -> 1 + no_leading_lambdas t
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247 let compute_max_lambdas_at hd_var j =
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248 let rec aux hd = function
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250 (if get_inert t1 = (hd, j)
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251 then max ( (*FIXME*)
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252 if is_inert t2 && let hd', j' = get_inert t2 in hd' = hd
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253 then let hd', j' = get_inert t2 in j - j'
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254 else no_leading_lambdas t2)
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255 else id) (max (aux hd t1) (aux hd t2))
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256 | L t -> aux (hd+1) t
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258 | _ -> assert false
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263 let hd_var, n_args = get_inert p.div in
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264 match get_subterm_with_head_and_args hd_var n_args p.conv with
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266 (try problem_fail (eat p) "Auto did not complete the problem" with Done _ -> ())
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268 let j = find_eta_difference p t n_args - 1 in
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270 (compute_max_lambdas_at hd_var j p.div)
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271 (compute_max_lambdas_at hd_var j p.conv) in
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272 let p = step j k p in
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276 let interactive div conv cmds =
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277 let p = problem_of div conv in
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279 let p = List.fold_left (|>) p cmds in
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281 let nth spl n = int_of_string (List.nth spl n) in
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283 let s = read_line () in
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284 let spl = Str.split (Str.regexp " +") s in
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285 s, let uno = List.hd spl in
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286 try if uno = "eat" then eat
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287 else if uno = "step" then step (nth spl 1) (nth spl 2)
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288 else failwith "Wrong input."
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289 with Failure s -> print_endline s; (fun x -> x) in
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290 let str, cmd = read_cmd () in
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291 let cmds = (" " ^ str ^ ";")::cmds in
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293 let p = cmd p in f p cmds
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295 | Done _ -> print_endline "Done! Commands history: "; List.iter print_endline (List.rev cmds)
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297 ) with Done _ -> ()
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300 let rec conv_join = function
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302 | x::xs -> conv_join xs ^ " ("^ x ^")"
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305 let auto' a b = auto (problem_of a (conv_join b));;
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307 (* Example usage of exec, interactive:
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311 (conv_join["x y"; "y y"; "y x"])
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316 "@ (x x) (y x) (y z)" [step 0 0; step 0 1; eat]
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321 auto' "x x" ["x y"; "y y"; "y x"] ;;
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322 auto' "x y" ["x (_. x)"; "y z"; "y x"] ;;
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323 auto' "a (x. x b) (x. x c)" ["a (x. b b) @"; "a @ c"; "a (x. x x) a"; "a (a a a) (a c c)"] ;;
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325 auto' "x (y. x y y)" ["x (y. x y x)"] ;;
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327 auto' "x a a a a" [
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334 (* Controesempio ad usare un conto dei lambda che non considere le permutazioni *)
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335 auto' "x a a a a (x (x. x x) @ @ (_._.x. x x) x) b b b" [
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336 "x a a a a (_. a) b b b";
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337 "x a a a a (_. _. _. _. x. y. x y)";
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342 print_endline "ALL DONE. "
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