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42 lines
872 B
Text
42 lines
872 B
Text
interface Variable
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exposes [Variable, fromUtf8, toIndex, totalCount, toStr]
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imports []
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# Variables in False can only be single letters. Thus, the valid variables are "a" to "z".
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# This opaque type deals with ensure we always have valid variables.
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Variable := U8
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totalCount : Nat
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totalCount =
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0x7A# "z"
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- 0x61# "a"
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+ 1
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toStr : Variable -> Str
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toStr = \@Variable char ->
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when Str.fromUtf8 [char] is
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Ok str ->
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str
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_ ->
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"_"
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fromUtf8 : U8 -> Result Variable [InvalidVariableUtf8]
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fromUtf8 = \char ->
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if
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char
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>= 0x61# "a"
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&& char
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<= 0x7A
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# "z"
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then
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Ok (@Variable char)
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else
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Err InvalidVariableUtf8
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toIndex : Variable -> Nat
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toIndex = \@Variable char ->
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Num.intCast (char - 0x61)# "a"
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# List.first (Str.toUtf8 "a")
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