77 lines
2.1 KiB
Forth
77 lines
2.1 KiB
Forth
module UnitsOfMeasure
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// The previous syntax defines unit-name as a unit of measure. The optional part is used to define a new measure in terms of previously defined units. For example, the following line defines the measure cm (centimeter).+
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// Distance, cm
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[<Measure>] type cm
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// The following line defines the measure ml (milliliter) as a cubic centimeter (cm^3).
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// Volume, milliliters.
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[<Measure>] type ml = cm^3
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// Mass, grams.
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[<Measure>] type g
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// Mass, kilograms.
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[<Measure>] type kg
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// Weight, pounds.
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[<Measure>] type lb
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// Distance, meters.
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[<Measure>] type m
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// Distance, inches.
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[<Measure>] type inch
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// Distance, feet
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[<Measure>] type ft
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// Time, seconds.
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[<Measure>] type s
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// Force, Newtons.
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[<Measure>] type N = kg m / s
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// Pressure, bar.
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[<Measure>] type bar
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// Pressure, Pascals
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[<Measure>] type Pa = N / m^2
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// Volume, liters.
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[<Measure>] type L
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// Define conversion constants.
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let gramsPerKilogram : float<g kg^-1> = 1000.0<g/kg>
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let cmPerMeter : float<cm/m> = 100.0<cm/m>
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let cmPerInch : float<cm/inch> = 2.54<cm/inch>
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let mlPerCubicCentimeter : float<ml/cm^3> = 1.0<ml/cm^3>
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let mlPerLiter : float<ml/L> = 1000.0<ml/L>
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// Define conversion functions.
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let convertGramsToKilograms (x : float<g>) = x / gramsPerKilogram
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let convertCentimetersToInches (x : float<cm>) = x / cmPerInch
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// Using Generic Units
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let genericSumUnits ( x : float<'u>) (y: float<'u>) = x + y
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let v1 = 3.1<m/s>
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let v2 = 2.7<m/s>
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let x1 = 1.2<m>
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let t1 = 1.0<s>
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// OK: a function that has unit consistency checking.
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let result1 = genericSumUnits v1 v2
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// Error reported: mismatched units.
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// Uncomment to see error.
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// let result2 = genericSumUnits v1 x1
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// Creating Aggregate Types with Generic Units
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// Define a vector together with a measure type parameter.
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// Note the attribute applied to the type parameter.
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type vector3D<[<Measure>] 'u> = { x : float<'u>; y : float<'u>; z : float<'u>}
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// Create instances that have two different measures.
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// Create a position vector.
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let xvec : vector3D<m> = { x = 0.0<m>; y = 0.0<m>; z = 0.0<m> }
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// Create a velocity vector.
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let v1vec : vector3D<m/s> = { x = 1.0<m/s>; y = -1.0<m/s>; z = 0.0<m/s> } |