author | nipkow |
Fri, 24 Oct 1997 18:10:51 +0200 | |
changeset 4003 | 2bbeed529077 |
parent 3244 | 71b760618f30 |
child 5021 | 235f8508d440 |
permissions | -rw-r--r-- |
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(* Title: Pure/basis.ML |
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ID: $Id$ |
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Author: Lawrence C Paulson, Cambridge University Computer Laboratory |
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Copyright 1993 University of Cambridge |
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Basis Library emulation. |
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Needed for Poly/ML and Standard ML of New Jersey version 0.93 to 1.08. |
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Full compatibility cannot be obtained using a file: what about char constants? |
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*) |
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exception Subscript; |
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structure Bool = |
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struct |
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fun toString true = "true" |
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| toString false = "false" |
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end; |
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Basis library version of type "option" now resides in its own structure Option
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structure Option = |
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struct |
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exception Option |
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datatype 'a option = NONE | SOME of 'a |
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fun getOpt (SOME v, _) = v |
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| getOpt (NONE, a) = a |
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fun isSome (SOME _) = true |
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| isSome NONE = false |
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fun valOf (SOME v) = v |
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| valOf NONE = raise Option |
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end; |
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structure Int = |
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struct |
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fun toString (i: int) = makestring i; |
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fun max (x, y) = if x < y then y else x : int; |
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fun min (x, y) = if x < y then x else y : int; |
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end; |
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structure List = |
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struct |
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exception Empty |
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fun last [] = raise Empty |
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| last [x] = x |
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| last (x::xs) = last xs; |
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fun nth (xs, n) = |
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let fun h [] _ = raise Subscript |
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| h (x::xs) n = if n=0 then x else h xs (n-1) |
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in if n<0 then raise Subscript else h xs n end; |
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fun drop (xs, n) = |
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let fun h xs 0 = xs |
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| h [] n = raise Subscript |
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| h (x::xs) n = h xs (n-1) |
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in if n<0 then raise Subscript else h xs n end; |
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fun take (xs, n) = |
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let fun h xs 0 = [] |
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| h [] n = raise Subscript |
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| h (x::xs) n = x :: h xs (n-1) |
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in if n<0 then raise Subscript else h xs n end; |
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fun concat [] = [] |
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| concat (l::ls) = l @ concat ls; |
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fun mapPartial f [] = [] |
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| mapPartial f (x::xs) = |
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(case f x of Option.NONE => mapPartial f xs |
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| Option.SOME y => y :: mapPartial f xs); |
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fun find _ [] = Option.NONE |
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| find p (x :: xs) = if p x then Option.SOME x else find p xs; |
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(*copy the list preserving elements that satisfy the predicate*) |
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fun filter p [] = [] |
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| filter p (x :: xs) = if p x then x :: filter p xs else filter p xs; |
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(*Partition list into elements that satisfy predicate and those that don't. |
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Preserves order of elements in both lists.*) |
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fun partition (p: 'a->bool) (ys: 'a list) : ('a list * 'a list) = |
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let fun part ([], answer) = answer |
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| part (x::xs, (ys, ns)) = if p(x) |
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then part (xs, (x::ys, ns)) |
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else part (xs, (ys, x::ns)) |
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in part (rev ys, ([], [])) end; |
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end; |
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structure ListPair = |
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struct |
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fun zip ([], []) = [] |
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| zip (x::xs,y::ys) = (x,y) :: zip(xs,ys); |
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fun unzip [] = ([],[]) |
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| unzip((x,y)::pairs) = |
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let val (xs,ys) = unzip pairs |
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in (x::xs, y::ys) end; |
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fun map f ([], []) = [] |
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| map f (x::xs,y::ys) = f(x,y) :: map f (xs,ys); |
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fun exists p = |
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let fun boolf ([], []) = false |
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| boolf (x::xs,y::ys) = p(x,y) orelse boolf (xs,ys) |
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in boolf end; |
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fun all p = |
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let fun boolf ([], []) = true |
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| boolf (x::xs,y::ys) = p(x,y) andalso boolf (xs,ys) |
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in boolf end; |
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end; |
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structure TextIO = |
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struct |
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type instream = instream |
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and outstream = outstream |
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exception Io of {name: string, function: string, cause: exn} |
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val stdIn = std_in |
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val stdOut = std_out |
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val openIn = open_in |
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val openAppend = open_append |
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val openOut = open_out |
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val closeIn = close_in |
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val closeOut = close_out |
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val inputN = input |
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val inputAll = fn is => inputN (is, 999999) |
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val inputLine = input_line |
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val endOfStream = end_of_stream |
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val output = output |
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val flushOut = flush_out |
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end; |
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A definition of "print", unfortunately overridden by each "open PolyML"
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A definition of "print", unfortunately overridden by each "open PolyML"
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A definition of "print", unfortunately overridden by each "open PolyML"
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fun print s = (output (std_out, s); flush_out std_out); |